From 7aa660981bd761920745dd69ad24624e10c9f9c1 Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Wed, 18 Mar 2026 10:29:56 +0900
Subject: [PATCH 01/13] Expose HDR features.

To Do: Add tests of the new features.
---
 interface/python_binding/buildscript.py       |  16 ++-
 .../pyktx/khr_df_color_model.py               | 126 ++++++++++++++++++
 .../python_binding/pyktx/khr_df_primaries.py  |  51 +++++++
 .../pyktx/khr_df_transfer_function.py         |  94 +++++++++++++
 .../python_binding/pyktx/ktx_basis_codec.py   |  18 +++
 .../python_binding/pyktx/ktx_basis_params.py  |  48 ++++++-
 interface/python_binding/pyktx/ktx_texture2.c |  23 +++-
 interface/python_binding/pyktx/ktx_texture2.h |  11 +-
 .../python_binding/pyktx/ktx_texture2.py      |  62 ++++++++-
 lib/include/ktx.h                             |  21 ++-
 10 files changed, 446 insertions(+), 24 deletions(-)
 create mode 100644 interface/python_binding/pyktx/khr_df_color_model.py
 create mode 100644 interface/python_binding/pyktx/khr_df_primaries.py
 create mode 100644 interface/python_binding/pyktx/khr_df_transfer_function.py
 create mode 100644 interface/python_binding/pyktx/ktx_basis_codec.py

diff --git a/interface/python_binding/buildscript.py b/interface/python_binding/buildscript.py
index 2a1e04759f..1b63334b54 100644
--- a/interface/python_binding/buildscript.py
+++ b/interface/python_binding/buildscript.py
@@ -81,10 +81,15 @@
                                       uint32_t faceSlice,
                                       void *src,
                                       size_t srcSize);
+    bool ktxTexture_IsHDR(ktxTexture *);
+    int ktxTexture2_DecodeAstc(void *);
     int ktxTexture2_TranscodeBasis(void *, int outputFormat, int transcodeFlags);
     int ktxTexture2_DeflateZstd(void *, uint32_t compressionLevel);
-    uint32_t ktxTexture2_GetOETF(void *);
+    uint32_t ktxTexture2_GetColorModel_e(void *);
+    uint32_t ktxTexture2_GetPrimaries_e(void *);
+    uint32_t ktxTexture2_GetTransferFunction_e(void *);
     bool ktxTexture2_GetPremultipliedAlpha(void *);
+    bool ktxTexture2_IsTranscodable(void *);
     bool ktxTexture2_NeedsTranscoding(void *);
 
     int ktxHashList_AddKVPair(ktxHashList *, const char *key, unsigned int valueLen, const void *value);
@@ -182,7 +187,14 @@
                                        float uastcRDOMaxSmoothBlockErrorScale,
                                        float uastcRDOMaxSmoothBlockStdDev,
                                        bool uastcRDODontFavorSimplerModes,
-                                       bool uastcRDONoMultithreading);
+                                       bool uastcRDONoMultithreading,
+                                       uint32_t uastcHDRQuality,
+                                       bool uastcHDRUberMode,
+                                       bool uastcHDRUltraQuant,
+                                       bool uastcHDRFavorAstc,
+                                       bool rec2020,
+                                       float uastcHDRLambda,
+                                       uint32_t uastcHDRLevel);
     uint32_t PY_ktxTexture2_get_vkFormat(void *);
     uint32_t PY_ktxTexture2_get_supercompressionScheme(void *);
     """
diff --git a/interface/python_binding/pyktx/khr_df_color_model.py b/interface/python_binding/pyktx/khr_df_color_model.py
new file mode 100644
index 0000000000..501460d70c
--- /dev/null
+++ b/interface/python_binding/pyktx/khr_df_color_model.py
@@ -0,0 +1,126 @@
+# Copyright (c) 2026, Mark Callow
+# SPDX-License-Identifier: Apache-2.0
+
+from enum import IntEnum
+
+class KhrDfColorModel(IntEnum):
+    """Model in which the color coordinate space is defined."""
+
+    KHR_DF_MODEL_UNSPECIFIED  = 0
+    """No interpretation of color channels defined."""
+
+    KHR_DF_MODEL_RGBSDA       = 1
+    """Color primaries (red, green, blue) + alpha, depth and stencil."""
+
+    KHR_DF_MODEL_YUVSDA       = 2
+    """Color differences (Y', Cb, Cr) + alpha, depth and stencil."""
+
+    KHR_DF_MODEL_YIQSDA       = 3
+    """Color differences (Y', I, Q) + alpha, depth and stencil."""
+
+    KHR_DF_MODEL_LABSDA       = 4
+    """Perceptual color (CIE L*a*b*) + alpha, depth and stencil."""
+
+    KHR_DF_MODEL_CMYKA        = 5
+    """Subtractive colors (cyan, magenta, yellow, black) + alpha."""
+
+    KHR_DF_MODEL_XYZW         = 6
+    """Non-color coordinate data (X, Y, Z, W)."""
+
+    KHR_DF_MODEL_HSVA_ANG     = 7
+    """Hue, saturation, value, hue angle on color circle, plus alpha."""
+
+    KHR_DF_MODEL_HSLA_ANG     = 8
+    """Hue, saturation, lightness, hue angle on color circle, plus alpha."""
+
+    KHR_DF_MODEL_HSVA_HEX     = 9
+    """Hue, saturation, value, hue on color hexagon, plus alpha."""
+
+    KHR_DF_MODEL_HSLA_HEX     = 10
+    """Hue, saturation, lightness, hue on color hexagon, plus alpha."""
+
+    KHR_DF_MODEL_YCGCOA       = 11
+    """Lightweight approximate color difference (luma, orange, green)."""
+
+    KHR_DF_MODEL_YCCBCCRC     = 12
+    """ITU BT.2020 constant luminance YcCbcCrc."""
+
+    KHR_DF_MODEL_ICTCP        = 13
+    """ITU BT.2100 constant intensity ICtCp."""
+
+    KHR_DF_MODEL_CIEXYZ       = 14
+    """CIE 1931 XYZ color coordinates (X, Y, Z)."""
+
+    KHR_DF_MODEL_CIEXYY       = 15
+    """CIE 1931 xyY color coordinates (X, Y, Y)."""
+
+
+    KHR_DF_MODEL_DXT1A         = 128
+    KHR_DF_MODEL_BC1A          = 128
+    """Compressed formats start at 128."""
+    """
+    Direct3D (and S3) compressed formats.
+        DXT1 "channels" are RGB (0), Alpha (1).
+        DXT1/BC1 with one channel is opaque.
+        DXT1/BC1 with a cosited alpha sample is transparent.
+    """
+
+    KHR_DF_MODEL_DXT2          = 129
+    KHR_DF_MODEL_DXT3          = 129
+    KHR_DF_MODEL_BC2           = 129
+    """DXT2/DXT3/BC2, with explicit 4-bit alpha."""
+
+    KHR_DF_MODEL_DXT4          = 130
+    KHR_DF_MODEL_DXT5          = 130
+    KHR_DF_MODEL_BC3           = 130
+    """DXT4/DXT5/BC3, with interpolated alpha."""
+
+    KHR_DF_MODEL_ATI1N         = 131
+    KHR_DF_MODEL_DXT5A         = 131
+    KHR_DF_MODEL_BC4           = 131
+    """ATI1n/DXT5A/BC4 - single channel interpolated 8-bit data.
+       (The UNORM/SNORM variation is recorded in the channel data)."""
+
+    KHR_DF_MODEL_ATI2N_XY      = 132
+    KHR_DF_MODEL_DXN           = 132
+    KHR_DF_MODEL_BC5           = 132
+    """ATI2n_XY/DXN/BC5 - two channel interpolated 8-bit data.
+       (The UNORM/SNORM variation is recorded in the channel data)."""
+
+    KHR_DF_MODEL_BC6H          = 133
+    """BC6H - DX11 format for 16-bit float channels."""
+
+    KHR_DF_MODEL_BC7           = 134
+    """BC7 - DX11 format."""
+
+    KHR_DF_MODEL_ETC1          = 160
+    """A format of ETC1 indicates that the format shall be decodable
+       by an ETC1-compliant decoder and not rely on ETC2 features."""
+
+    KHR_DF_MODEL_ETC2          = 161
+    """A format of ETC2 is permitted to use ETC2 encodings on top of
+       the baseline ETC1 specification.
+       The ETC2 format has channels "red", "green", "RGB" and "alpha",
+       which should be cosited samples.
+       Punch-through alpha can be distinguished from full alpha by
+       the plane size in bytes required for the texel block."""
+
+    KHR_DF_MODEL_ASTC          = 162
+    """Adaptive Scalable Texture Compression."""
+    """ASTC HDR vs LDR is determined by the float flag in the channel."""
+    """ASTC block size can be distinguished by texel block size."""
+
+    KHR_DF_MODEL_ETC1S         = 163
+    """ETC1S is a simplified subset of ETC1."""
+
+    KHR_DF_MODEL_PVRTC         = 164
+    KHR_DF_MODEL_PVRTC2        = 165
+    """PowerVR Texture Compression."""
+
+    KHR_DF_MODEL_UASTC         = 166
+    KHR_DF_MODEL_UASTC_LDR_4x4 = 166
+    KHR_DF_MODEL_UASTC_HDR_4x4 = 167
+    KHR_DF_MODEL_UASTC_HDR_6x6 = 168
+    """UASTC for BASIS supercompression."""
+
+    KHR_DF_MODEL_MAX = 0xFF
diff --git a/interface/python_binding/pyktx/khr_df_primaries.py b/interface/python_binding/pyktx/khr_df_primaries.py
new file mode 100644
index 0000000000..ba8f669f33
--- /dev/null
+++ b/interface/python_binding/pyktx/khr_df_primaries.py
@@ -0,0 +1,51 @@
+# Copyright (c) 2026, Mark Callow
+# SPDX-License-Identifier: Apache-2.0
+
+from enum import IntEnum
+
+class KhrDfPrimaries(IntEnum):
+    """The primary colors of an image."""
+
+    KHR_DF_PRIMARIES_UNSPECIFIED = 0
+    """No color primaries defined"""
+
+    KHR_DF_PRIMARIES_BT709       = 1
+    """Color primaries of ITU-R BT.709 and sRGB"""
+
+    KHR_DF_PRIMARIES_SRGB        = 1
+    """Synonym for KHR_DF_PRIMARIES_BT709"""
+
+    KHR_DF_PRIMARIES_BT601_EBU   = 2
+    """Color primaries of ITU-R BT.601 (625-line EBU variant)"""
+
+    KHR_DF_PRIMARIES_BT601_SMPTE = 3
+    """Color primaries of ITU-R BT.601 (525-line SMPTE C variant)"""
+
+    KHR_DF_PRIMARIES_BT2020      = 4
+    """Color primaries of ITU-R BT.2020"""
+
+    KHR_DF_PRIMARIES_BT2100      = 4
+    """ITU-R BT.2100 uses the same primaries as BT.2020"""
+
+    KHR_DF_PRIMARIES_CIEXYZ      = 5
+    """CIE theoretical color coordinate space"""
+
+    KHR_DF_PRIMARIES_ACES        = 6
+    """Academy Color Encoding System primaries"""
+
+    KHR_DF_PRIMARIES_ACESCC      = 7
+    """Color primaries of ACEScc"""
+
+    KHR_DF_PRIMARIES_NTSC1953    = 8
+    """Legacy NTSC 1953 primaries"""
+
+    KHR_DF_PRIMARIES_PAL525      = 9
+    """Legacy PAL 525-line primaries"""
+
+    KHR_DF_PRIMARIES_DISPLAYP3   = 10
+    """Color primaries of Display P3"""
+
+    KHR_DF_PRIMARIES_ADOBERGB    = 11
+    """Color primaries of Adobe RGB (1998)"""
+
+    KHR_DF_PRIMARIES_MAX         = 0xFF
diff --git a/interface/python_binding/pyktx/khr_df_transfer_function.py b/interface/python_binding/pyktx/khr_df_transfer_function.py
new file mode 100644
index 0000000000..716b43a2b0
--- /dev/null
+++ b/interface/python_binding/pyktx/khr_df_transfer_function.py
@@ -0,0 +1,94 @@
+# Copyright (c) 2026, Mark Callow
+# SPDX-License-Identifier: Apache-2.0
+
+from enum import IntEnum
+
+class KhrDfTransferFunction(IntEnum):
+    """The transfer function of an image."""
+
+    TRANSFER_UNSPECIFIED = 0
+    """No transfer function defined."""
+
+    TRANSFER_LINEAR      = 1
+    """Linear transfer function (value proportional to intensity."""
+
+    TRANSFER_SRGB        = 2
+    TRANSFER_SRGB_EOTF   = 2
+    TRANSFER_SCRGB       = 2
+    TRANSFER_SCRGB_EOTF  = 2
+    """Perceptually-linear transfer function of sRGB (~2.2); also used for scRGB."""
+
+    TRANSFER_ITU         = 3
+    TRANSFER_ITU_OETF    = 3
+    TRANSFER_BT601       = 3
+    TRANSFER_BT601_OETF  = 3
+    TRANSFER_BT709       = 3
+    TRANSFER_BT709_OETF  = 3
+    TRANSFER_BT2020      = 3
+    TRANSFER_BT2020_OETF = 3
+    """Perceptually-linear transfer function of ITU BT.601, BT.709 and BT.2020 (~1/.45)."""
+
+    TRANSFER_SMTPE170M      = 3
+    TRANSFER_SMTPE170M_OETF = 3
+    TRANSFER_SMTPE170M_EOTF = 3
+    """SMTPE170M (digital NTSC) defines an alias for the ITU transfer function (~1/.45) and a linear OOTF."""
+
+    TRANSFER_NTSC        = 4
+    TRANSFER_NTSC_EOTF   = 4
+    """Perceptually-linear gamma function of original NTSC (simple 2.2 gamma)."""
+
+    TRANSFER_SLOG        = 5
+    TRANSFER_SLOG_OETF   = 5
+    """Sony S-log used by Sony video cameras."""
+
+    TRANSFER_SLOG2       = 6
+    TRANSFER_SLOG2_OETF  = 6
+    """Sony S-log 2 used by Sony video cameras."""
+
+    TRANSFER_BT1886      = 7
+    TRANSFER_BT1886_EOTF = 7
+    """ITU BT.1886 EOTF."""
+
+    TRANSFER_HLG_OETF    = 8
+    """ITU BT.2100 HLG OETF (typical scene-referred content), linear light normalized 0..1."""
+
+    TRANSFER_HLG_EOTF    = 9
+    """ITU BT.2100 HLG EOTF (nominal HDR display of HLG content), linear light normalized 0..1."""
+
+    TRANSFER_PQ_EOTF     = 10
+    """ITU BT.2100 PQ EOTF (typical HDR display-referred PQ content)."""
+
+    TRANSFER_PQ_OETF     = 11
+    """ITU BT.2100 PQ OETF (nominal scene described by PQ HDR content)."""
+
+    TRANSFER_DCIP3       = 12
+    TRANSFER_DCIP3_EOTF  = 12
+    """DCI P3 transfer function."""
+
+    TRANSFER_PAL_OETF    = 13
+    """Legacy PAL OETF."""
+
+    TRANSFER_PAL625_EOTF = 14
+    """Legacy PAL 625-line EOTF."""
+
+    TRANSFER_ST240       = 15
+    TRANSFER_ST240_OETF  = 15
+    TRANSFER_ST240_EOTF  = 15
+    """Legacy ST240 transfer function."""
+
+    TRANSFER_ACESCC      = 16
+    TRANSFER_ACESCC_OETF = 16
+    """ACEScc transfer function."""
+
+    TRANSFER_ACESCCT      = 17
+    TRANSFER_ACESCCT_OETF = 17
+    """ACEScct transfer function."""
+
+    TRANSFER_ADOBERGB      = 18
+    TRANSFER_ADOBERGB_EOTF = 18
+    """Adobe RGB (1998) transfer function."""
+
+    TRANSFER_HLG_UNNORMALIZED_OETF = 19
+    """Legacy ITU BT.2100 HLG OETF (typical scene-referred content), linear light normalized 0..12."""
+
+    TRANSFER_MAX                   = 0xFF
diff --git a/interface/python_binding/pyktx/ktx_basis_codec.py b/interface/python_binding/pyktx/ktx_basis_codec.py
new file mode 100644
index 0000000000..3bcbc44107
--- /dev/null
+++ b/interface/python_binding/pyktx/ktx_basis_codec.py
@@ -0,0 +1,18 @@
+# Copyright (c) 2026, Mark Callow
+# SPDX-License-Identifier: Apache-2.0
+
+from enum import IntEnum
+
+class KtxBasisCodec(IntEnum):
+    """Options specifiying basis codec."""
+
+    NONE  = 0
+    """NONE."""
+    ETC1S   = 1
+    """BasisLZ."""
+    UASTC_LDR_4x4   = 2
+    """UASTC."""
+    UASTC_HDR_4x4   = 3
+    """UASTC_HDR_4x4."""
+    UASTC_HDR_6x6_INTERMEDIATE = 4
+    """UASTC_HDR_6x6i."""
diff --git a/interface/python_binding/pyktx/ktx_basis_params.py b/interface/python_binding/pyktx/ktx_basis_params.py
index c30fa38f60..be865b4f8e 100644
--- a/interface/python_binding/pyktx/ktx_basis_params.py
+++ b/interface/python_binding/pyktx/ktx_basis_params.py
@@ -2,15 +2,15 @@
 # SPDX-License-Identifier: Apache-2.0
 
 from dataclasses import dataclass
+from .ktx_basis_codec import KtxBasisCodec
 from .ktx_pack_uastc_flag_bits import KtxPackUastcFlagBits
 
-
 @dataclass
 class KtxBasisParams:
     """Data for passing extended params to KtxTexture2.compressBasis()."""
 
-    uastc: bool = False
-    """True to use UASTC base, false to use ETC1S base."""
+    codec: int = KtxBasisCodec.ETC1S
+    """Basis Universal codec to use. Default is ETC1S/BasisLZ."""
 
     verbose: bool = False
     """If true, prints Basis Universal encoder operation details to stdout. Not recommended for GUI apps."""
@@ -170,3 +170,45 @@ class KtxBasisParams:
 
     uastc_rdo_no_multithreading: bool = False
     """Disable RDO multithreading (slightly higher compression, deterministic)."""
+
+    # UASTC HDR params
+
+    uastc_hdr_quality: int = 1
+    """
+    Valid range is [0,4] - higher=slower but higher quality. Default=1.
+    Level 0=fastest/lowest quality, 3=highest practical setting, 4=exhaustive
+    """
+
+    uastc_hdr_uber_mode: bool = False
+    """
+    UASTC HDR 4x4: Allow the UASTC HDR 4x4 encoder to try varying the CEM 11
+    selectors more for slightly higher quality (slower). This may negatively impact BC6H quality, however.
+    """
+
+    uastc_hdr_ultra_quant: bool = False
+    """UASTC HDR 4x4: Try to find better quantized CEM 7/11 endpoint values (slower)."""
+
+    uastc_hdr_favor_astc: bool = False
+    """
+    UASTC HDR 4x4: By default the UASTC HDR 4x4 encoder tries to strike a balance
+    or even slightly favor BC6H quality. If this option is specified, ASTC HDR 4x4 quality is favored instead.
+    """
+
+    rec_2020: bool = False
+    """
+    UASTC HDR 6x6i specific option: The input image's gamut is Rec. 2020 vs. the
+    default Rec. 709 - for accurate colorspace error calculations.
+    """
+
+    uastc_hdr_lambda: float = 0.
+    """
+    UASTC HDR 6x6i specific option: Enables rate distortion optimization (RDO).
+    The higher this value, the lower the quality, but the smaller the file size.
+    Try 100-20000, or higher values on some images.
+    """
+
+    uastc_hdr_level: int = 2
+    """
+    UASTC HDR 6x6i specific option: Controls the 6x6 HDR intermediate mode encoder
+    performance vs. max quality tradeoff. X may range from [0,12]. Default level is 2.
+    """
diff --git a/interface/python_binding/pyktx/ktx_texture2.c b/interface/python_binding/pyktx/ktx_texture2.c
index f1f6a4ce84..eb5ccd3a25 100644
--- a/interface/python_binding/pyktx/ktx_texture2.c
+++ b/interface/python_binding/pyktx/ktx_texture2.c
@@ -79,7 +79,7 @@ KTX_error_code PY_ktxTexture2_CompressAstcEx(ktxTexture2 *texture,
 }
 
 KTX_error_code PY_ktxTexture2_CompressBasisEx(ktxTexture2 *texture,
-                                              ktx_bool_t uastc,
+                                              int codec,
                                               ktx_bool_t verbose,
                                               ktx_bool_t noSSE,
                                               ktx_uint32_t threadCount,
@@ -102,11 +102,19 @@ KTX_error_code PY_ktxTexture2_CompressBasisEx(ktxTexture2 *texture,
                                               float uastcRDOMaxSmoothBlockErrorScale,
                                               float uastcRDOMaxSmoothBlockStdDev,
                                               ktx_bool_t uastcRDODontFavorSimplerModes,
-                                              ktx_bool_t uastcRDONoMultithreading)
+                                              ktx_bool_t uastcRDONoMultithreading,
+                                              ktx_uint32_t uastcHDRQuality,
+                                              ktx_bool_t uastcHDRUberMode,
+                                              ktx_bool_t uastcHDRUltraQuant,
+                                              ktx_bool_t uastcHDRFavorAstc,
+                                              ktx_bool_t rec2020,
+                                              float uastcHDRLambda,
+                                              ktx_uint32_t uastcHDRLevel
+                                              )
 {
     ktxBasisParams params = {
         .structSize = sizeof(ktxBasisParams),
-        .codec = (uastc) ? KTX_BASIS_CODEC_UASTC_LDR_4x4 : KTX_BASIS_CODEC_ETC1S,
+        .codec = codec,
         .verbose = verbose,
         .noSSE = noSSE,
         .threadCount = threadCount,
@@ -128,7 +136,14 @@ KTX_error_code PY_ktxTexture2_CompressBasisEx(ktxTexture2 *texture,
         .uastcRDOMaxSmoothBlockErrorScale = uastcRDOMaxSmoothBlockErrorScale,
         .uastcRDOMaxSmoothBlockStdDev = uastcRDOMaxSmoothBlockStdDev,
         .uastcRDODontFavorSimplerModes = uastcRDODontFavorSimplerModes,
-        .uastcRDONoMultithreading = uastcRDONoMultithreading
+        .uastcRDONoMultithreading = uastcRDONoMultithreading,
+        .uastcHDRQuality = uastcHDRQuality,
+        .uastcHDRUberMode = uastcHDRUberMode,
+        .uastcHDRUltraQuant = uastcHDRUltraQuant,
+        .uastcHDRFavorAstc = uastcHDRFavorAstc,
+        .rec2020 = rec2020,
+        .uastcHDRLambda = uastcHDRLambda,
+        .uastcHDRLevel = uastcHDRLevel
     };
 
     params.inputSwizzle[0] = inputSwizzle[0];
diff --git a/interface/python_binding/pyktx/ktx_texture2.h b/interface/python_binding/pyktx/ktx_texture2.h
index 27427908a7..d97e8ef991 100644
--- a/interface/python_binding/pyktx/ktx_texture2.h
+++ b/interface/python_binding/pyktx/ktx_texture2.h
@@ -34,7 +34,7 @@ KTX_error_code PY_ktxTexture2_CompressAstcEx(ktxTexture2 *texture,
                                              char *inputSwizzle);
 
 KTX_error_code PY_ktxTexture2_CompressBasisEx(ktxTexture2 *texture,
-                                              ktx_bool_t uastc,
+                                              int codec,
                                               ktx_bool_t verbose,
                                               ktx_bool_t noSSE,
                                               ktx_uint32_t threadCount,
@@ -57,7 +57,14 @@ KTX_error_code PY_ktxTexture2_CompressBasisEx(ktxTexture2 *texture,
                                               float uastcRDOMaxSmoothBlockErrorScale,
                                               float uastcRDOMaxSmoothBlockStdDev,
                                               ktx_bool_t uastcRDODontFavorSimplerModes,
-                                              ktx_bool_t uastcRDONoMultithreading);
+                                              ktx_bool_t uastcRDONoMultithreading,
+                                              ktx_uint32_t uastcHDRQuality,
+                                              ktx_bool_t uastcHDRUberMode,
+                                              ktx_bool_t uastcHDRUltraQuant,
+                                              ktx_bool_t uastcHDRFavorAstc,
+                                              ktx_bool_t rec2020,
+                                              float uastcHDRLambda,
+                                              ktx_uint32_t uastcHDRLevel);
 
 #define KTX2_GETTER(type, prop) \
     type PY_ktxTexture2_get_##prop(ktxTexture2 *texture)
diff --git a/interface/python_binding/pyktx/ktx_texture2.py b/interface/python_binding/pyktx/ktx_texture2.py
index 4940a33abb..1b6c6c6ce8 100644
--- a/interface/python_binding/pyktx/ktx_texture2.py
+++ b/interface/python_binding/pyktx/ktx_texture2.py
@@ -1,6 +1,9 @@
 # Copyright (c) 2023, Shukant Pal and Contributors
 # SPDX-License-Identifier: Apache-2.0
 
+from .khr_df_color_model import KhrDfColorModel
+from .khr_df_primaries import KhrDfPrimaries
+from .khr_df_transfer_function import KhrDfTransferFunction
 from .ktx_astc_params import KtxAstcParams
 from .ktx_basis_params import KtxBasisParams
 from .ktx_error_code import KtxErrorCode, KtxError
@@ -71,10 +74,22 @@ def supercompression_scheme(self) -> KtxSupercmpScheme:
         return KtxSupercmpScheme(lib.PY_ktxTexture2_get_supercompressionScheme(self._ptr))
 
     @property
-    def oetf(self) -> int:
-        """The opto-electrical transfer function of the images."""
+    def color_model(self) -> KhrDfColorModel:
+        """The color model of the images."""
 
-        return lib.ktxTexture2_GetOETF(self._ptr)
+        return KhrDfColorModel(lib.ktxTexture2_GetColorModel_e(self._ptr))
+
+    @property
+    def primaries(self) -> KhrDfPrimaries:
+        """The color primaries of the images."""
+
+        return KhrDfPrimaries(lib.ktxTexture2_GetPrimaries_e(self._ptr))
+
+    @property
+    def transfer_function(self) -> KhrDfTransferFunction:
+        """The transfer function of the images."""
+
+        return KhrDfTransferFunction(lib.ktxTexture2_GetTransferFunction_e(self._ptr))
 
     @property
     def premultipled_alpha(self) -> bool:
@@ -82,9 +97,21 @@ def premultipled_alpha(self) -> bool:
 
         return lib.ktxTexture2_GetPremultipliedAlpha(self._ptr)
 
+    @property
+    def is_hdr(self) -> bool:
+        """Whether the images are in an HDR format."""
+
+        return lib.ktxTexture_IsHDR(self._ptr)
+
+    @property
+    def is_transcodable(self) -> bool:
+        """If the images are in a format that can be transcoded."""
+
+        return lib.ktxTexture2_IsTranscodable(self._ptr)
+
     @property
     def needs_transcoding(self) -> bool:
-        """If the images are in a transcodable format."""
+        """If the images are in a format that must be transcoded."""
 
         return lib.ktxTexture2_NeedsTranscoding(self._ptr)
 
@@ -135,7 +162,7 @@ def compress_basis(self, params: Union[int, KtxBasisParams]) -> None:
             params.quality_level = quality
 
         error = lib.PY_ktxTexture2_CompressBasisEx(self._ptr,
-                                                   params.uastc,
+                                                   params.codec,
                                                    params.verbose,
                                                    params.no_sse,
                                                    params.thread_count,
@@ -158,11 +185,34 @@ def compress_basis(self, params: Union[int, KtxBasisParams]) -> None:
                                                    params.uastc_rdo_max_smooth_block_error_scale,
                                                    params.uastc_rdo_max_smooth_block_std_dev,
                                                    params.uastc_rdo_dont_favor_simpler_modes,
-                                                   params.uastc_rdo_no_multithreading)
+                                                   params.uastc_rdo_no_multithreading,
+                                                   params.uastc_hdr_quality,
+                                                   params.uastc_hdr_uber_mode,
+                                                   params.uastc_hdr_ultra_quant,
+                                                   params.uastc_hdr_favor_astc,
+                                                   params.rec_2020,
+                                                   params.uastc_hdr_lambda,
+                                                   params.uastc_hdr_level
+                                                   )
 
         if int(error) != KtxErrorCode.SUCCESS:
             raise KtxError('ktxTexture2_CompressBasisEx', KtxErrorCode(error))
 
+    def decode_astc(self) -> None:
+        """
+        Decode a ktx2 texture object, if it is ASTC encoded.
+
+        The decompressed format is calculated from corresponding ASTC format.
+        There are only 3 possible options currently supported. RGBA8, SRGBA8
+        and RGBA32.
+
+        Note that 3d textures are decoded to a multi-slice 3d texture.
+        """
+
+        error = lib.ktxTexture2_DecodeAstc(self._ptr);
+        if int(error) != KtxErrorCode.SUCCESS:
+            raise KtxError('ktx2_DecodeAstc', KtxErrorCode(error))
+
     def deflate_zstd(self, compression_level: int) -> None:
         """
         Deflate the data in a ktxTexture2 object using Zstandard.
diff --git a/lib/include/ktx.h b/lib/include/ktx.h
index 964f3d7a3f..bdf810b61b 100644
--- a/lib/include/ktx.h
+++ b/lib/include/ktx.h
@@ -1573,26 +1573,33 @@ typedef struct ktxBasisParams {
              deterministic).
          */
     ktx_uint32_t uastcHDRQuality;
-        /*!< UASTC HDR 4x4: Sets the UASTC HDR 4x4 compressor's level. Valid range is [0,4] - higher=slower but higher quality. HDR default=1.
-		                    Level 0=fastest/lowest quality, 3=highest practical setting, 4=exhaustive
+        /*!< UASTC HDR 4x4: Sets the UASTC HDR 4x4 compressor's level.
+             Valid range is [0,4] - higher=slower but higher quality. Default=1.
+             Level 0=fastest/lowest quality, 3=highest practical setting, 4=exhaustive
          */
     ktx_bool_t uastcHDRUberMode;
-        /*!< UASTC HDR 4x4: Allow the UASTC HDR 4x4 encoder to try varying the CEM 11 selectors more for slightly higher quality (slower). This may negatively impact BC6H quality, however.
+        /*!< UASTC HDR 4x4: Allow the UASTC HDR 4x4 encoder to try varying the CEM 11
+             selectors more for slightly higher quality (slower). This may negatively impact BC6H quality, however.
          */
     ktx_bool_t uastcHDRUltraQuant;
         /*!< UASTC HDR 4x4: Try to find better quantized CEM 7/11 endpoint values (slower)
          */
     ktx_bool_t uastcHDRFavorAstc;
-        /*!< UASTC HDR 4x4: By default the UASTC HDR 4x4 encoder tries to strike a balance or even slightly favor BC6H quality. If this option is specified, ASTC HDR 4x4 quality is favored instead.
+        /*!< UASTC HDR 4x4: By default the UASTC HDR 4x4 encoder tries to strike a balance
+             or even slightly favor BC6H quality. If this option is specified, ASTC HDR 4x4 quality is favored instead.
          */
     ktx_bool_t rec2020;
-        /*!< UASTC HDR 6x6i specific option: The input image's gamut is Rec. 2020 vs. the default Rec. 709 - for accurate colorspace error calculations.
+        /*!< UASTC HDR 6x6i specific option: The input image's gamut is Rec. 2020 vs. the
+             default Rec. 709 - for accurate colorspace error calculations.
          */
     float uastcHDRLambda;
-        /*!< UASTC HDR 6x6i specific option: Enables rate distortion optimization (RDO). The higher this value, the lower the quality, but the smaller the file size. Try 100-20000, or higher values on some images.
+        /*!< UASTC HDR 6x6i specific option: Enables rate distortion optimization (RDO).
+             The higher this value, the lower the quality, but the smaller the file size. Try 100-20000, or higher values
+             on some images.
          */
     ktx_uint32_t uastcHDRLevel;
-        /*!< UASTC HDR 6x6i specific option: Controls the 6x6 HDR intermediate mode encoder performance vs. max quality tradeoff. X may range from [0,12]. Default level is 2.
+        /*!< UASTC HDR 6x6i specific option: Controls the 6x6 HDR intermediate mode encoder
+             performance vs. max quality tradeoff. X may range from [0,12]. Default level is 2.
          */
 
 } ktxBasisParams;

From e2c45fc4ba45192b9600b95f87f124bae56e5ebd Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Wed, 18 Mar 2026 22:47:33 +0900
Subject: [PATCH 02/13] Expose ktxTexture[12]_IsHDR.

---
 lib/include/ktx.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/include/ktx.h b/lib/include/ktx.h
index bdf810b61b..235e12df1d 100644
--- a/lib/include/ktx.h
+++ b/lib/include/ktx.h
@@ -1061,6 +1061,9 @@ ktxTexture1_CreateFromStream(ktxStream* stream,
 KTX_API void KTX_APIENTRY
 ktxTexture1_Destroy(ktxTexture1* This);
 
+KTX_API ktx_bool_t KTX_APIENTRY
+ktxTexture1_IsHDR(ktxTexture1* This);
+
 KTX_API ktx_bool_t KTX_APIENTRY
 ktxTexture1_NeedsTranscoding(ktxTexture1* This);
 
@@ -1180,6 +1183,9 @@ ktxTexture2_GetPremultipliedAlpha(ktxTexture2* This);
 KTX_API khr_df_primaries_e KTX_APIENTRY
 ktxTexture2_GetPrimaries_e(ktxTexture2* This);
 
+KTX_API ktx_bool_t KTX_APIENTRY
+ktxTexture2_IsHDR(ktxTexture2* This);
+
 KTX_API ktx_bool_t KTX_APIENTRY
 ktxTexture2_NeedsTranscoding(ktxTexture2* This);
 

From 47345553a97efa390622901e9b9e7a3d3bea362f Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Wed, 18 Mar 2026 22:48:37 +0900
Subject: [PATCH 03/13] Remove prefices from enumeration names.

---
 .../pyktx/khr_df_color_model.py               | 86 +++++++++---------
 .../python_binding/pyktx/khr_df_primaries.py  | 32 +++----
 .../pyktx/khr_df_transfer_function.py         | 88 +++++++++----------
 3 files changed, 103 insertions(+), 103 deletions(-)

diff --git a/interface/python_binding/pyktx/khr_df_color_model.py b/interface/python_binding/pyktx/khr_df_color_model.py
index 501460d70c..cfe5d4bc55 100644
--- a/interface/python_binding/pyktx/khr_df_color_model.py
+++ b/interface/python_binding/pyktx/khr_df_color_model.py
@@ -6,57 +6,57 @@
 class KhrDfColorModel(IntEnum):
     """Model in which the color coordinate space is defined."""
 
-    KHR_DF_MODEL_UNSPECIFIED  = 0
+    UNSPECIFIED  = 0
     """No interpretation of color channels defined."""
 
-    KHR_DF_MODEL_RGBSDA       = 1
+    RGBSDA       = 1
     """Color primaries (red, green, blue) + alpha, depth and stencil."""
 
-    KHR_DF_MODEL_YUVSDA       = 2
+    YUVSDA       = 2
     """Color differences (Y', Cb, Cr) + alpha, depth and stencil."""
 
-    KHR_DF_MODEL_YIQSDA       = 3
+    YIQSDA       = 3
     """Color differences (Y', I, Q) + alpha, depth and stencil."""
 
-    KHR_DF_MODEL_LABSDA       = 4
+    LABSDA       = 4
     """Perceptual color (CIE L*a*b*) + alpha, depth and stencil."""
 
-    KHR_DF_MODEL_CMYKA        = 5
+    CMYKA        = 5
     """Subtractive colors (cyan, magenta, yellow, black) + alpha."""
 
-    KHR_DF_MODEL_XYZW         = 6
+    XYZW         = 6
     """Non-color coordinate data (X, Y, Z, W)."""
 
-    KHR_DF_MODEL_HSVA_ANG     = 7
+    HSVA_ANG     = 7
     """Hue, saturation, value, hue angle on color circle, plus alpha."""
 
-    KHR_DF_MODEL_HSLA_ANG     = 8
+    HSLA_ANG     = 8
     """Hue, saturation, lightness, hue angle on color circle, plus alpha."""
 
-    KHR_DF_MODEL_HSVA_HEX     = 9
+    HSVA_HEX     = 9
     """Hue, saturation, value, hue on color hexagon, plus alpha."""
 
-    KHR_DF_MODEL_HSLA_HEX     = 10
+    HSLA_HEX     = 10
     """Hue, saturation, lightness, hue on color hexagon, plus alpha."""
 
-    KHR_DF_MODEL_YCGCOA       = 11
+    YCGCOA       = 11
     """Lightweight approximate color difference (luma, orange, green)."""
 
-    KHR_DF_MODEL_YCCBCCRC     = 12
+    YCCBCCRC     = 12
     """ITU BT.2020 constant luminance YcCbcCrc."""
 
-    KHR_DF_MODEL_ICTCP        = 13
+    ICTCP        = 13
     """ITU BT.2100 constant intensity ICtCp."""
 
-    KHR_DF_MODEL_CIEXYZ       = 14
+    CIEXYZ       = 14
     """CIE 1931 XYZ color coordinates (X, Y, Z)."""
 
-    KHR_DF_MODEL_CIEXYY       = 15
+    CIEXYY       = 15
     """CIE 1931 xyY color coordinates (X, Y, Y)."""
 
 
-    KHR_DF_MODEL_DXT1A         = 128
-    KHR_DF_MODEL_BC1A          = 128
+    DXT1A         = 128
+    BC1A          = 128
     """Compressed formats start at 128."""
     """
     Direct3D (and S3) compressed formats.
@@ -65,39 +65,39 @@ class KhrDfColorModel(IntEnum):
         DXT1/BC1 with a cosited alpha sample is transparent.
     """
 
-    KHR_DF_MODEL_DXT2          = 129
-    KHR_DF_MODEL_DXT3          = 129
-    KHR_DF_MODEL_BC2           = 129
+    DXT2          = 129
+    DXT3          = 129
+    BC2           = 129
     """DXT2/DXT3/BC2, with explicit 4-bit alpha."""
 
-    KHR_DF_MODEL_DXT4          = 130
-    KHR_DF_MODEL_DXT5          = 130
-    KHR_DF_MODEL_BC3           = 130
+    DXT4          = 130
+    DXT5          = 130
+    BC3           = 130
     """DXT4/DXT5/BC3, with interpolated alpha."""
 
-    KHR_DF_MODEL_ATI1N         = 131
-    KHR_DF_MODEL_DXT5A         = 131
-    KHR_DF_MODEL_BC4           = 131
+    ATI1N         = 131
+    DXT5A         = 131
+    BC4           = 131
     """ATI1n/DXT5A/BC4 - single channel interpolated 8-bit data.
        (The UNORM/SNORM variation is recorded in the channel data)."""
 
-    KHR_DF_MODEL_ATI2N_XY      = 132
-    KHR_DF_MODEL_DXN           = 132
-    KHR_DF_MODEL_BC5           = 132
+    ATI2N_XY      = 132
+    DXN           = 132
+    BC5           = 132
     """ATI2n_XY/DXN/BC5 - two channel interpolated 8-bit data.
        (The UNORM/SNORM variation is recorded in the channel data)."""
 
-    KHR_DF_MODEL_BC6H          = 133
+    BC6H          = 133
     """BC6H - DX11 format for 16-bit float channels."""
 
-    KHR_DF_MODEL_BC7           = 134
+    BC7           = 134
     """BC7 - DX11 format."""
 
-    KHR_DF_MODEL_ETC1          = 160
+    ETC1          = 160
     """A format of ETC1 indicates that the format shall be decodable
        by an ETC1-compliant decoder and not rely on ETC2 features."""
 
-    KHR_DF_MODEL_ETC2          = 161
+    ETC2          = 161
     """A format of ETC2 is permitted to use ETC2 encodings on top of
        the baseline ETC1 specification.
        The ETC2 format has channels "red", "green", "RGB" and "alpha",
@@ -105,22 +105,22 @@ class KhrDfColorModel(IntEnum):
        Punch-through alpha can be distinguished from full alpha by
        the plane size in bytes required for the texel block."""
 
-    KHR_DF_MODEL_ASTC          = 162
+    ASTC          = 162
     """Adaptive Scalable Texture Compression."""
     """ASTC HDR vs LDR is determined by the float flag in the channel."""
     """ASTC block size can be distinguished by texel block size."""
 
-    KHR_DF_MODEL_ETC1S         = 163
+    ETC1S         = 163
     """ETC1S is a simplified subset of ETC1."""
 
-    KHR_DF_MODEL_PVRTC         = 164
-    KHR_DF_MODEL_PVRTC2        = 165
+    PVRTC         = 164
+    PVRTC2        = 165
     """PowerVR Texture Compression."""
 
-    KHR_DF_MODEL_UASTC         = 166
-    KHR_DF_MODEL_UASTC_LDR_4x4 = 166
-    KHR_DF_MODEL_UASTC_HDR_4x4 = 167
-    KHR_DF_MODEL_UASTC_HDR_6x6 = 168
+    UASTC         = 166
+    UASTC_LDR_4x4 = 166
+    UASTC_HDR_4x4 = 167
+    UASTC_HDR_6x6 = 168
     """UASTC for BASIS supercompression."""
 
-    KHR_DF_MODEL_MAX = 0xFF
+    MAX = 0xFF
diff --git a/interface/python_binding/pyktx/khr_df_primaries.py b/interface/python_binding/pyktx/khr_df_primaries.py
index ba8f669f33..ef20144a9f 100644
--- a/interface/python_binding/pyktx/khr_df_primaries.py
+++ b/interface/python_binding/pyktx/khr_df_primaries.py
@@ -6,46 +6,46 @@
 class KhrDfPrimaries(IntEnum):
     """The primary colors of an image."""
 
-    KHR_DF_PRIMARIES_UNSPECIFIED = 0
+    UNSPECIFIED = 0
     """No color primaries defined"""
 
-    KHR_DF_PRIMARIES_BT709       = 1
+    BT709       = 1
     """Color primaries of ITU-R BT.709 and sRGB"""
 
-    KHR_DF_PRIMARIES_SRGB        = 1
-    """Synonym for KHR_DF_PRIMARIES_BT709"""
+    SRGB        = 1
+    """Synonym for BT709"""
 
-    KHR_DF_PRIMARIES_BT601_EBU   = 2
+    BT601_EBU   = 2
     """Color primaries of ITU-R BT.601 (625-line EBU variant)"""
 
-    KHR_DF_PRIMARIES_BT601_SMPTE = 3
+    BT601_SMPTE = 3
     """Color primaries of ITU-R BT.601 (525-line SMPTE C variant)"""
 
-    KHR_DF_PRIMARIES_BT2020      = 4
+    BT2020      = 4
     """Color primaries of ITU-R BT.2020"""
 
-    KHR_DF_PRIMARIES_BT2100      = 4
+    BT2100      = 4
     """ITU-R BT.2100 uses the same primaries as BT.2020"""
 
-    KHR_DF_PRIMARIES_CIEXYZ      = 5
+    CIEXYZ      = 5
     """CIE theoretical color coordinate space"""
 
-    KHR_DF_PRIMARIES_ACES        = 6
+    ACES        = 6
     """Academy Color Encoding System primaries"""
 
-    KHR_DF_PRIMARIES_ACESCC      = 7
+    ACESCC      = 7
     """Color primaries of ACEScc"""
 
-    KHR_DF_PRIMARIES_NTSC1953    = 8
+    NTSC1953    = 8
     """Legacy NTSC 1953 primaries"""
 
-    KHR_DF_PRIMARIES_PAL525      = 9
+    PAL525      = 9
     """Legacy PAL 525-line primaries"""
 
-    KHR_DF_PRIMARIES_DISPLAYP3   = 10
+    DISPLAYP3   = 10
     """Color primaries of Display P3"""
 
-    KHR_DF_PRIMARIES_ADOBERGB    = 11
+    ADOBERGB    = 11
     """Color primaries of Adobe RGB (1998)"""
 
-    KHR_DF_PRIMARIES_MAX         = 0xFF
+    MAX         = 0xFF
diff --git a/interface/python_binding/pyktx/khr_df_transfer_function.py b/interface/python_binding/pyktx/khr_df_transfer_function.py
index 716b43a2b0..633e05c798 100644
--- a/interface/python_binding/pyktx/khr_df_transfer_function.py
+++ b/interface/python_binding/pyktx/khr_df_transfer_function.py
@@ -6,89 +6,89 @@
 class KhrDfTransferFunction(IntEnum):
     """The transfer function of an image."""
 
-    TRANSFER_UNSPECIFIED = 0
+    UNSPECIFIED = 0
     """No transfer function defined."""
 
-    TRANSFER_LINEAR      = 1
+    LINEAR      = 1
     """Linear transfer function (value proportional to intensity."""
 
-    TRANSFER_SRGB        = 2
-    TRANSFER_SRGB_EOTF   = 2
-    TRANSFER_SCRGB       = 2
-    TRANSFER_SCRGB_EOTF  = 2
+    SRGB        = 2
+    SRGB_EOTF   = 2
+    SCRGB       = 2
+    SCRGB_EOTF  = 2
     """Perceptually-linear transfer function of sRGB (~2.2); also used for scRGB."""
 
-    TRANSFER_ITU         = 3
-    TRANSFER_ITU_OETF    = 3
-    TRANSFER_BT601       = 3
-    TRANSFER_BT601_OETF  = 3
-    TRANSFER_BT709       = 3
-    TRANSFER_BT709_OETF  = 3
-    TRANSFER_BT2020      = 3
-    TRANSFER_BT2020_OETF = 3
+    ITU         = 3
+    ITU_OETF    = 3
+    BT601       = 3
+    BT601_OETF  = 3
+    BT709       = 3
+    BT709_OETF  = 3
+    BT2020      = 3
+    BT2020_OETF = 3
     """Perceptually-linear transfer function of ITU BT.601, BT.709 and BT.2020 (~1/.45)."""
 
-    TRANSFER_SMTPE170M      = 3
-    TRANSFER_SMTPE170M_OETF = 3
-    TRANSFER_SMTPE170M_EOTF = 3
+    SMTPE170M      = 3
+    SMTPE170M_OETF = 3
+    SMTPE170M_EOTF = 3
     """SMTPE170M (digital NTSC) defines an alias for the ITU transfer function (~1/.45) and a linear OOTF."""
 
-    TRANSFER_NTSC        = 4
-    TRANSFER_NTSC_EOTF   = 4
+    NTSC        = 4
+    NTSC_EOTF   = 4
     """Perceptually-linear gamma function of original NTSC (simple 2.2 gamma)."""
 
-    TRANSFER_SLOG        = 5
-    TRANSFER_SLOG_OETF   = 5
+    SLOG        = 5
+    SLOG_OETF   = 5
     """Sony S-log used by Sony video cameras."""
 
-    TRANSFER_SLOG2       = 6
-    TRANSFER_SLOG2_OETF  = 6
+    SLOG2       = 6
+    SLOG2_OETF  = 6
     """Sony S-log 2 used by Sony video cameras."""
 
-    TRANSFER_BT1886      = 7
-    TRANSFER_BT1886_EOTF = 7
+    BT1886      = 7
+    BT1886_EOTF = 7
     """ITU BT.1886 EOTF."""
 
-    TRANSFER_HLG_OETF    = 8
+    HLG_OETF    = 8
     """ITU BT.2100 HLG OETF (typical scene-referred content), linear light normalized 0..1."""
 
-    TRANSFER_HLG_EOTF    = 9
+    HLG_EOTF    = 9
     """ITU BT.2100 HLG EOTF (nominal HDR display of HLG content), linear light normalized 0..1."""
 
-    TRANSFER_PQ_EOTF     = 10
+    PQ_EOTF     = 10
     """ITU BT.2100 PQ EOTF (typical HDR display-referred PQ content)."""
 
-    TRANSFER_PQ_OETF     = 11
+    PQ_OETF     = 11
     """ITU BT.2100 PQ OETF (nominal scene described by PQ HDR content)."""
 
-    TRANSFER_DCIP3       = 12
-    TRANSFER_DCIP3_EOTF  = 12
+    DCIP3       = 12
+    DCIP3_EOTF  = 12
     """DCI P3 transfer function."""
 
-    TRANSFER_PAL_OETF    = 13
+    PAL_OETF    = 13
     """Legacy PAL OETF."""
 
-    TRANSFER_PAL625_EOTF = 14
+    PAL625_EOTF = 14
     """Legacy PAL 625-line EOTF."""
 
-    TRANSFER_ST240       = 15
-    TRANSFER_ST240_OETF  = 15
-    TRANSFER_ST240_EOTF  = 15
+    ST240       = 15
+    ST240_OETF  = 15
+    ST240_EOTF  = 15
     """Legacy ST240 transfer function."""
 
-    TRANSFER_ACESCC      = 16
-    TRANSFER_ACESCC_OETF = 16
+    ACESCC      = 16
+    ACESCC_OETF = 16
     """ACEScc transfer function."""
 
-    TRANSFER_ACESCCT      = 17
-    TRANSFER_ACESCCT_OETF = 17
+    ACESCCT      = 17
+    ACESCCT_OETF = 17
     """ACEScct transfer function."""
 
-    TRANSFER_ADOBERGB      = 18
-    TRANSFER_ADOBERGB_EOTF = 18
+    ADOBERGB      = 18
+    ADOBERGB_EOTF = 18
     """Adobe RGB (1998) transfer function."""
 
-    TRANSFER_HLG_UNNORMALIZED_OETF = 19
+    HLG_UNNORMALIZED_OETF = 19
     """Legacy ITU BT.2100 HLG OETF (typical scene-referred content), linear light normalized 0..12."""
 
-    TRANSFER_MAX                   = 0xFF
+    MAX                   = 0xFF

From d3caaf87c2ac6ced80318bf3c3f62a194f4f12f7 Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Wed, 18 Mar 2026 22:50:36 +0900
Subject: [PATCH 04/13] Move properties from virtual functions to ktx_texture.

---
 interface/python_binding/buildscript.py        |  4 ++--
 interface/python_binding/pyktx/ktx_texture.py  | 18 ++++++++++++++++++
 interface/python_binding/pyktx/ktx_texture2.py | 18 ------------------
 3 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/interface/python_binding/buildscript.py b/interface/python_binding/buildscript.py
index 1b63334b54..5e281fd296 100644
--- a/interface/python_binding/buildscript.py
+++ b/interface/python_binding/buildscript.py
@@ -82,6 +82,8 @@
                                       void *src,
                                       size_t srcSize);
     bool ktxTexture_IsHDR(ktxTexture *);
+    bool ktxTexture_IsTranscodable(ktxTexture *);
+    bool ktxTexture_NeedsTranscoding(ktxTexture *);
     int ktxTexture2_DecodeAstc(void *);
     int ktxTexture2_TranscodeBasis(void *, int outputFormat, int transcodeFlags);
     int ktxTexture2_DeflateZstd(void *, uint32_t compressionLevel);
@@ -89,8 +91,6 @@
     uint32_t ktxTexture2_GetPrimaries_e(void *);
     uint32_t ktxTexture2_GetTransferFunction_e(void *);
     bool ktxTexture2_GetPremultipliedAlpha(void *);
-    bool ktxTexture2_IsTranscodable(void *);
-    bool ktxTexture2_NeedsTranscoding(void *);
 
     int ktxHashList_AddKVPair(ktxHashList *, const char *key, unsigned int valueLen, const void *value);
     int ktxHashList_DeleteKVPair(ktxHashList *, const char *key);
diff --git a/interface/python_binding/pyktx/ktx_texture.py b/interface/python_binding/pyktx/ktx_texture.py
index 2da6b15c52..4c46167adf 100644
--- a/interface/python_binding/pyktx/ktx_texture.py
+++ b/interface/python_binding/pyktx/ktx_texture.py
@@ -140,6 +140,24 @@ def data_size_uncompressed(self) -> int:
 
         return lib.ktxTexture_GetDataSizeUncompressed(self._ptr)
 
+    @property
+    def is_hdr(self) -> bool:
+        """Whether the images are in an HDR format."""
+
+        return lib.ktxTexture_IsHDR(self._ptr)
+
+    @property
+    def is_transcodable(self) -> bool:
+        """If the images are in a format that can be transcoded."""
+
+        return lib.ktxTexture_IsTranscodable(self._ptr)
+
+    @property
+    def needs_transcoding(self) -> bool:
+        """If the images are in a format that must be transcoded."""
+
+        return lib.ktxTexture_NeedsTranscoding(self._ptr)
+
     def row_pitch(self, level: int) -> int:
         """
         Return pitch between rows of a texture image level in bytes.
diff --git a/interface/python_binding/pyktx/ktx_texture2.py b/interface/python_binding/pyktx/ktx_texture2.py
index 1b6c6c6ce8..4894c06bc2 100644
--- a/interface/python_binding/pyktx/ktx_texture2.py
+++ b/interface/python_binding/pyktx/ktx_texture2.py
@@ -97,24 +97,6 @@ def premultipled_alpha(self) -> bool:
 
         return lib.ktxTexture2_GetPremultipliedAlpha(self._ptr)
 
-    @property
-    def is_hdr(self) -> bool:
-        """Whether the images are in an HDR format."""
-
-        return lib.ktxTexture_IsHDR(self._ptr)
-
-    @property
-    def is_transcodable(self) -> bool:
-        """If the images are in a format that can be transcoded."""
-
-        return lib.ktxTexture2_IsTranscodable(self._ptr)
-
-    @property
-    def needs_transcoding(self) -> bool:
-        """If the images are in a format that must be transcoded."""
-
-        return lib.ktxTexture2_NeedsTranscoding(self._ptr)
-
     def compress_astc(self, params: Union[int, KtxAstcParams]) -> None:
         """
         Encode and compress a ktx texture with uncompressed images to ASTC.

From b362987d9242e43bbb110ff5f904a4a9674fedca Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Wed, 18 Mar 2026 22:51:43 +0900
Subject: [PATCH 05/13] Add simple test of property queries.

---
 interface/python_binding/tests/test_ktx_texture2.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/interface/python_binding/tests/test_ktx_texture2.py b/interface/python_binding/tests/test_ktx_texture2.py
index 90b92a3b95..606c2fd125 100644
--- a/interface/python_binding/tests/test_ktx_texture2.py
+++ b/interface/python_binding/tests/test_ktx_texture2.py
@@ -103,3 +103,13 @@ def test_create(self):
         texture = KtxTexture2.create(info, KtxTextureCreateStorage.ALLOC)
         self.assertEqual(texture.vk_format, VkFormat.VK_FORMAT_ASTC_4x4_SRGB_BLOCK)
         texture.set_image_from_memory(0, 0, 0, bytes(texture.data_size))
+
+    def test_queries(self):
+        test_ktx_file = os.path.join(__test_images__, 'ktx2/alpha_simple_blze.ktx2')
+        texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
+        self.assertTrue(texture.needs_transcoding)
+        self.assertTrue(texture.is_transcodable)
+        self.assertFalse(texture.is_hdr);
+        self.assertEqual(texture.color_model, KhrDfColorModel.ETC1S)
+        self.assertEqual(texture.primaries, KhrDfPrimaries.BT709)
+        self.assertEqual(texture.transfer_function, KhrDfTransferFunction.SRGB)

From 17accb30e66570467dc7563b27c4197766a38e0a Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 11:23:16 +0900
Subject: [PATCH 06/13] Match khr_df.h names.

---
 .../pyktx/{khr_df_color_model.py => khr_df_model.py} |  2 +-
 ...hr_df_transfer_function.py => khr_df_transfer.py} |  2 +-
 interface/python_binding/pyktx/ktx_texture2.py       | 12 ++++++------
 interface/python_binding/tests/test_ktx_texture2.py  |  4 ++--
 4 files changed, 10 insertions(+), 10 deletions(-)
 rename interface/python_binding/pyktx/{khr_df_color_model.py => khr_df_model.py} (99%)
 rename interface/python_binding/pyktx/{khr_df_transfer_function.py => khr_df_transfer.py} (98%)

diff --git a/interface/python_binding/pyktx/khr_df_color_model.py b/interface/python_binding/pyktx/khr_df_model.py
similarity index 99%
rename from interface/python_binding/pyktx/khr_df_color_model.py
rename to interface/python_binding/pyktx/khr_df_model.py
index cfe5d4bc55..2693c96c5b 100644
--- a/interface/python_binding/pyktx/khr_df_color_model.py
+++ b/interface/python_binding/pyktx/khr_df_model.py
@@ -3,7 +3,7 @@
 
 from enum import IntEnum
 
-class KhrDfColorModel(IntEnum):
+class KhrDfModel(IntEnum):
     """Model in which the color coordinate space is defined."""
 
     UNSPECIFIED  = 0
diff --git a/interface/python_binding/pyktx/khr_df_transfer_function.py b/interface/python_binding/pyktx/khr_df_transfer.py
similarity index 98%
rename from interface/python_binding/pyktx/khr_df_transfer_function.py
rename to interface/python_binding/pyktx/khr_df_transfer.py
index 633e05c798..140613fce2 100644
--- a/interface/python_binding/pyktx/khr_df_transfer_function.py
+++ b/interface/python_binding/pyktx/khr_df_transfer.py
@@ -3,7 +3,7 @@
 
 from enum import IntEnum
 
-class KhrDfTransferFunction(IntEnum):
+class KhrDfTransfer(IntEnum):
     """The transfer function of an image."""
 
     UNSPECIFIED = 0
diff --git a/interface/python_binding/pyktx/ktx_texture2.py b/interface/python_binding/pyktx/ktx_texture2.py
index 4894c06bc2..5efc4e36d5 100644
--- a/interface/python_binding/pyktx/ktx_texture2.py
+++ b/interface/python_binding/pyktx/ktx_texture2.py
@@ -1,9 +1,9 @@
 # Copyright (c) 2023, Shukant Pal and Contributors
 # SPDX-License-Identifier: Apache-2.0
 
-from .khr_df_color_model import KhrDfColorModel
+from .khr_df_model import KhrDfModel
 from .khr_df_primaries import KhrDfPrimaries
-from .khr_df_transfer_function import KhrDfTransferFunction
+from .khr_df_transfer import KhrDfTransfer
 from .ktx_astc_params import KtxAstcParams
 from .ktx_basis_params import KtxBasisParams
 from .ktx_error_code import KtxErrorCode, KtxError
@@ -74,10 +74,10 @@ def supercompression_scheme(self) -> KtxSupercmpScheme:
         return KtxSupercmpScheme(lib.PY_ktxTexture2_get_supercompressionScheme(self._ptr))
 
     @property
-    def color_model(self) -> KhrDfColorModel:
+    def color_model(self) -> KhrDfModel:
         """The color model of the images."""
 
-        return KhrDfColorModel(lib.ktxTexture2_GetColorModel_e(self._ptr))
+        return KhrDfModel(lib.ktxTexture2_GetColorModel_e(self._ptr))
 
     @property
     def primaries(self) -> KhrDfPrimaries:
@@ -86,10 +86,10 @@ def primaries(self) -> KhrDfPrimaries:
         return KhrDfPrimaries(lib.ktxTexture2_GetPrimaries_e(self._ptr))
 
     @property
-    def transfer_function(self) -> KhrDfTransferFunction:
+    def transfer_function(self) -> KhrDfTransfer:
         """The transfer function of the images."""
 
-        return KhrDfTransferFunction(lib.ktxTexture2_GetTransferFunction_e(self._ptr))
+        return KhrDfTransfer(lib.ktxTexture2_GetTransferFunction_e(self._ptr))
 
     @property
     def premultipled_alpha(self) -> bool:
diff --git a/interface/python_binding/tests/test_ktx_texture2.py b/interface/python_binding/tests/test_ktx_texture2.py
index 606c2fd125..bcb7b36b84 100644
--- a/interface/python_binding/tests/test_ktx_texture2.py
+++ b/interface/python_binding/tests/test_ktx_texture2.py
@@ -110,6 +110,6 @@ def test_queries(self):
         self.assertTrue(texture.needs_transcoding)
         self.assertTrue(texture.is_transcodable)
         self.assertFalse(texture.is_hdr);
-        self.assertEqual(texture.color_model, KhrDfColorModel.ETC1S)
+        self.assertEqual(texture.color_model, KhrDfModel.ETC1S)
         self.assertEqual(texture.primaries, KhrDfPrimaries.BT709)
-        self.assertEqual(texture.transfer_function, KhrDfTransferFunction.SRGB)
+        self.assertEqual(texture.transfer_function, KhrDfTransfer.SRGB)

From d3c1e972989df2c69df6be41be1982d619d0b94c Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 11:53:45 +0900
Subject: [PATCH 07/13] Add num_layers property.

---
 interface/python_binding/buildscript.py       | 1 +
 interface/python_binding/pyktx/ktx_texture.c  | 1 +
 interface/python_binding/pyktx/ktx_texture.h  | 1 +
 interface/python_binding/pyktx/ktx_texture.py | 6 ++++++
 4 files changed, 9 insertions(+)

diff --git a/interface/python_binding/buildscript.py b/interface/python_binding/buildscript.py
index 5e281fd296..c7d8d681e8 100644
--- a/interface/python_binding/buildscript.py
+++ b/interface/python_binding/buildscript.py
@@ -113,6 +113,7 @@
     uint32_t PY_ktxTexture_get_baseHeight(ktxTexture *);
     uint32_t PY_ktxTexture_get_baseDepth(ktxTexture *);
     uint32_t PY_ktxTexture_get_numDimensions(ktxTexture *);
+    uint32_t PY_ktxTexture_get_numLayers(ktxTexture *);
     uint32_t PY_ktxTexture_get_numLevels(ktxTexture *);
     uint32_t PY_ktxTexture_get_numFaces(ktxTexture *);
     uint32_t PY_ktxTexture_get_kvDataLen(ktxTexture *);
diff --git a/interface/python_binding/pyktx/ktx_texture.c b/interface/python_binding/pyktx/ktx_texture.c
index 2479c996b6..f6bb0e9f05 100644
--- a/interface/python_binding/pyktx/ktx_texture.c
+++ b/interface/python_binding/pyktx/ktx_texture.c
@@ -88,6 +88,7 @@ KTX_IMPL(ktx_uint32_t, baseWidth);
 KTX_IMPL(ktx_uint32_t, baseHeight);
 KTX_IMPL(ktx_uint32_t, baseDepth);
 KTX_IMPL(ktx_uint32_t, numDimensions);
+KTX_IMPL(ktx_uint32_t, numLayers);
 KTX_IMPL(ktx_uint32_t, numLevels);
 KTX_IMPL(ktx_uint32_t, numFaces);
 KTX_IMPL(ktx_uint32_t, kvDataLen);
diff --git a/interface/python_binding/pyktx/ktx_texture.h b/interface/python_binding/pyktx/ktx_texture.h
index 9be170c263..c3f75a01df 100644
--- a/interface/python_binding/pyktx/ktx_texture.h
+++ b/interface/python_binding/pyktx/ktx_texture.h
@@ -46,6 +46,7 @@ KTX_GETTER(ktx_uint32_t, baseWidth);
 KTX_GETTER(ktx_uint32_t, baseHeight);
 KTX_GETTER(ktx_uint32_t, baseDepth);
 KTX_GETTER(ktx_uint32_t, numDimensions);
+KTX_GETTER(ktx_uint32_t, numLayers);
 KTX_GETTER(ktx_uint32_t, numLevels);
 KTX_GETTER(ktx_uint32_t, numFaces);
 KTX_GETTER(ktx_uint32_t, kvDataLen);
diff --git a/interface/python_binding/pyktx/ktx_texture.py b/interface/python_binding/pyktx/ktx_texture.py
index 4c46167adf..986ca042a7 100644
--- a/interface/python_binding/pyktx/ktx_texture.py
+++ b/interface/python_binding/pyktx/ktx_texture.py
@@ -85,6 +85,12 @@ def num_dimensions(self) -> int:
 
         return lib.PY_ktxTexture_get_numDimensions(self._ptr)
 
+    @property
+    def num_layers(self) -> int:
+        """Number of layers in the texture."""
+
+        return lib.PY_ktxTexture_get_numLayers(self._ptr)
+
     @property
     def num_levels(self) -> int:
         """Number of mip levels in the texture."""

From 603d6f62442a0ea6318edac882fa747ea93733f7 Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 12:29:22 +0900
Subject: [PATCH 08/13] Fix CompressBasisEx interface.

---
 interface/python_binding/buildscript.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/interface/python_binding/buildscript.py b/interface/python_binding/buildscript.py
index c7d8d681e8..13686bb914 100644
--- a/interface/python_binding/buildscript.py
+++ b/interface/python_binding/buildscript.py
@@ -165,7 +165,7 @@
                                       bool perceptual,
                                       char *inputSwizzle);
     int PY_ktxTexture2_CompressBasisEx(void *texture,
-                                       bool uastc,
+                                       uint32_t codec,
                                        bool verbose,
                                        bool noSSE,
                                        uint32_t threadCount,

From 558aa9e7eeff9770fa82061d12f94d3cfbc928af Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 12:30:35 +0900
Subject: [PATCH 09/13] Add tests.

Now tests queries, astc compress, with and without params,astc decode and
basis compress with and without params.
---
 .../python_binding/tests/test_ktx_texture2.py | 68 ++++++++++++++++++-
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/interface/python_binding/tests/test_ktx_texture2.py b/interface/python_binding/tests/test_ktx_texture2.py
index bcb7b36b84..707f22c5c5 100644
--- a/interface/python_binding/tests/test_ktx_texture2.py
+++ b/interface/python_binding/tests/test_ktx_texture2.py
@@ -11,8 +11,9 @@ def test_create_from_named_file(self):
         test_ktx_file = os.path.join(__test_images__, 'ktx2/alpha_complex_straight.ktx2')
         texture = KtxTexture2.create_from_named_file(test_ktx_file)
 
-        self.assertEqual(texture.num_levels, 1)
         self.assertEqual(texture.num_faces, 1)
+        self.assertEqual(texture.num_layers, 1)
+        self.assertEqual(texture.num_levels, 1)
         self.assertEqual(texture.vk_format, VkFormat.VK_FORMAT_R8G8B8A8_SRGB)
         self.assertEqual(texture.base_width, 256)
         self.assertEqual(texture.base_height, 256)
@@ -23,6 +24,7 @@ def test_create_from_named_file_mipmapped(self):
         texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.NO_FLAGS)
 
         self.assertEqual(texture.vk_format, VkFormat.VK_FORMAT_ASTC_8x8_SRGB_BLOCK)
+        self.assertEqual(texture.num_layers, 1)
         self.assertEqual(texture.num_levels, 11)
         self.assertEqual(texture.base_width, 1024)
         self.assertEqual(texture.base_height, 1024)
@@ -76,14 +78,30 @@ def test_compress_basis(self):
         test_ktx_file = os.path.join(__test_images__, 'ktx2/r8g8b8a8_srgb_array_7_mip.ktx2')
         texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
 
+        self.assertEqual(texture.color_model, KhrDfModel.RGBSDA)
         self.assertEqual(texture.is_compressed, False)
         self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.NONE)
 
-        texture.compress_basis(KtxBasisParams(quality_level=1))
+        texture.compress_basis(1)
 
+        self.assertEqual(texture.color_model, KhrDfModel.ETC1S)
         self.assertEqual(texture.is_compressed, True)
         self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.BASIS_LZ)
 
+    def test_compress_basis_with_params(self):
+        test_ktx_file = os.path.join(__test_images__, 'ktx2/r8g8b8a8_srgb_array_7_mip.ktx2')
+        texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
+
+        self.assertEqual(texture.color_model, KhrDfModel.RGBSDA)
+        self.assertEqual(texture.is_compressed, False)
+        self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.NONE)
+
+        texture.compress_basis(KtxBasisParams(codec=KtxBasisCodec.UASTC_LDR_4x4,uastc_rdo=True))
+
+        self.assertEqual(texture.color_model, KhrDfModel.UASTC)
+        self.assertEqual(texture.is_compressed, True)
+        self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.NONE)
+
     def test_transcode_basis(self):
         test_ktx_file = os.path.join(__test_images__, 'ktx2/color_grid_blze.ktx2')
         texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
@@ -110,6 +128,52 @@ def test_queries(self):
         self.assertTrue(texture.needs_transcoding)
         self.assertTrue(texture.is_transcodable)
         self.assertFalse(texture.is_hdr);
+        self.assertFalse(texture.premultipled_alpha)
         self.assertEqual(texture.color_model, KhrDfModel.ETC1S)
         self.assertEqual(texture.primaries, KhrDfPrimaries.BT709)
         self.assertEqual(texture.transfer_function, KhrDfTransfer.SRGB)
+
+    def test_compress_astc(self):
+        test_ktx_file = os.path.join(__test_images__, 'ktx2/r8g8b8a8_srgb_array_7_mip.ktx2')
+        texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
+        self.assertFalse(texture.is_compressed)
+        self.assertEqual(texture.num_layers, 7)
+        self.assertEqual(texture.transfer_function, KhrDfTransfer.SRGB)
+        texture.compress_astc(KtxPackAstcQualityLevels.FAST)
+        self.assertTrue(texture.is_compressed)
+        self.assertEqual(texture.color_model, KhrDfModel.ASTC)
+        self.assertEqual(texture.num_layers, 7)
+        self.assertEqual(texture.transfer_function, KhrDfTransfer.SRGB)
+
+    def test_compress_astc_with_params(self):
+        test_ktx_file = os.path.join(__test_images__, 'ktx2/r8g8b8a8_srgb_array_7_mip.ktx2')
+        texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
+        self.assertFalse(texture.is_compressed)
+        self.assertEqual(texture.num_layers, 7)
+        self.assertEqual(texture.transfer_function, KhrDfTransfer.SRGB)
+        texture.compress_astc(KtxAstcParams(quality_level=KtxPackAstcQualityLevels.FAST,
+                                            block_dimension=KtxPackAstcBlockDimension.D8x8))
+        self.assertTrue(texture.is_compressed)
+        self.assertEqual(texture.color_model, KhrDfModel.ASTC)
+        self.assertEqual(texture.num_layers, 7)
+        self.assertEqual(texture.transfer_function, KhrDfTransfer.SRGB)
+
+    def test_decode_astc(self):
+        test_ktx_file = os.path.join(__test_images__, 'ktx2/astc_8x8_unorm_array_7.ktx2')
+        texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
+        self.assertEqual(texture.color_model, KhrDfModel.ASTC)
+        self.assertTrue(texture.is_compressed)
+        self.assertTrue(texture.is_array)
+        self.assertFalse(texture.is_hdr);
+        self.assertFalse(texture.premultipled_alpha)
+        self.assertEqual(texture.num_layers, 7)
+        self.assertFalse(texture.needs_transcoding)
+        texture.decode_astc();
+        self.assertFalse(texture.is_compressed)
+        self.assertEqual(texture.color_model, KhrDfModel.RGBSDA)
+        self.assertEqual(texture.transfer_function, KhrDfTransfer.LINEAR)
+        self.assertTrue(texture.is_array)
+        self.assertFalse(texture.is_hdr);
+        self.assertFalse(texture.premultipled_alpha)
+        self.assertEqual(texture.num_layers, 7)
+        self.assertFalse(texture.needs_transcoding)

From 833beadcef3e37450fc482ded386211f11c3fc94 Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 18:01:08 +0900
Subject: [PATCH 10/13] Polish the documentation.

---
 interface/python_binding/conf.py              |  1 +
 .../python_binding/pyktx/ktx_basis_params.py  | 39 ++++++++++---------
 interface/python_binding/pyktx/ktx_texture.py |  9 ++++-
 3 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/interface/python_binding/conf.py b/interface/python_binding/conf.py
index a9ed752eae..16961d64ee 100644
--- a/interface/python_binding/conf.py
+++ b/interface/python_binding/conf.py
@@ -41,6 +41,7 @@
     'sphinx.ext.napoleon',
 ]
 
+autodoc_member_order = 'bysource'
 templates_path = ['_templates']
 exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
diff --git a/interface/python_binding/pyktx/ktx_basis_params.py b/interface/python_binding/pyktx/ktx_basis_params.py
index be865b4f8e..f35fb6a13a 100644
--- a/interface/python_binding/pyktx/ktx_basis_params.py
+++ b/interface/python_binding/pyktx/ktx_basis_params.py
@@ -7,10 +7,10 @@
 
 @dataclass
 class KtxBasisParams:
-    """Data for passing extended params to KtxTexture2.compressBasis()."""
+    """Struct for passing extended params to KtxTexture2.compressBasis()."""
 
     codec: int = KtxBasisCodec.ETC1S
-    """Basis Universal codec to use. Default is ETC1S/BasisLZ."""
+    """Basis Universal codec to use. Default is KtxBasisCodec.ETC1S/BasisLZ."""
 
     verbose: bool = False
     """If true, prints Basis Universal encoder operation details to stdout. Not recommended for GUI apps."""
@@ -21,9 +21,12 @@ class KtxBasisParams:
     thread_count: int = 1
     """Number of threads used for compression. Default is 1."""
 
+    # Here and in the descriptions of all other codec specific options we abuse the
+    # fact that ':'in a docstring is used to indicate the preceding text is a
+    # type so that the target codec is clearly flagged on a separate "Type: " line.
     etc1s_compression_level: int = 0
     """
-    Encoding speed vs. quality tradeoff for etc1s. Range is [0,5].
+    ETC1S/BasisLZ: Encoding speed vs. quality tradeoff for etc1s. Range is [0,5].
 
     Higher values are slower, but give higher quality. There is no default.
     Callers must explicitly set this value. Callers can use
@@ -32,7 +35,7 @@ class KtxBasisParams:
 
     quality_level: int = 0
     """
-    Compression quality. Range is [1,255].
+    ETC1S/BasisLZ and UASTC LDR 4x4: Compression quality. Range is [1,255].
 
     Lower gives better compression/lower quality/faster.
     Higher gives less compression/higher quality/slower.
@@ -49,7 +52,7 @@ class KtxBasisParams:
 
     max_endpoints: int = 0
     """
-    Manually set the max number of color endpoint clusters.
+    ETC1S/BasisLZ: Manually set the max number of color endpoint clusters.
 
     Range is [1,16128]. Default is 0, unset. If this is set, max_selectors
     must also be set, otherwise the value will be ignored.
@@ -57,7 +60,7 @@ class KtxBasisParams:
 
     endpoint_rdo_threshold: int = 0
     """
-    Set endpoint RDO quality threshold. The default is 1.25.
+    ETC1S/BasisLZ: Set endpoint RDO quality threshold. The default is 1.25.
 
     Lower is higher quality but less quality per output bit (try [1.0,3.0].
     This will override the value chosen by quality_level.
@@ -65,7 +68,7 @@ class KtxBasisParams:
 
     max_selectors: int = 0
     """
-    Manually set the max number of color selector clusters. Range is [1,16128].
+    ETC1S/BasisLZ: Manually set the max number of color selector clusters. Range is [1,16128].
 
     Default is 0, unset. If this is set, max_endpoints must also be set, otherwise
     the value will be ignored.
@@ -73,7 +76,7 @@ class KtxBasisParams:
 
     selector_rdo_threshold: int = 0
     """
-    Set selector RDO quality threshold. The default is 1.5.
+    ETC1S/BasisLZ:  Set selector RDO quality threshold. The default is 1.5.
 
     Lower is higher quality but less quality per output bit (try [1.0,3.0]).
     This will override the value chosen by @c qualityLevel.
@@ -113,32 +116,32 @@ class KtxBasisParams:
 
     no_endpoint_rdo: bool = False
     """
-    Disable endpoint rate distortion optimizations.
+    ETC1S/BasisLZ: Disable endpoint rate distortion optimizations.
 
     Slightly faster, less noisy output, but lower quality per output bit.
     """
 
     no_selector_rdo: bool = False
     """
-    Disable selector rate distortion optimizations.
+    ETC1S/BasisLZ: Disable selector rate distortion optimizations.
 
     Slightly faster, less noisy output, but lower quality per output bit.
     """
 
     uastc_flags: int = KtxPackUastcFlagBits.FASTEST
     """
-    A set of KtxPackUastcFlagBits controlling UASTC encoding.
+    UASTC LDR 4x4: A set of KtxPackUastcFlagBits controlling UASTC encoding.
 
     The most important value is the level given in the
     least-significant 4 bits which selects a speed vs quality tradeoff.
     """
 
     uastc_rdo: bool = False
-    """Enable Rate Distortion Optimization (RDO) post-processing."""
+    """UASTC LDR 4x4: Enable Rate Distortion Optimization (RDO) post-processing."""
 
     uastc_rdo_quality_scalar: float = 0.
     """
-    UASTC RDO quality scalar (lambda).
+    UASTC LDR 4x4: RDO quality scalar (lambda).
 
     Lower values yield higher quality/larger LZ compressed files, higher
     values yield lower quality/smaller LZ compressed files. A good range to
@@ -147,29 +150,29 @@ class KtxBasisParams:
 
     uastc_rdo_dict_size: int = 0
     """
-    UASTC RDO dictionary size in bytes. Default is 4096. Lower
+    UASTC LDR 4x4: RDO dictionary size in bytes. Default is 4096. Lower
     values=faster, but give less compression. Range is [64,65536].
     """
 
     uastc_rdo_max_smooth_block_error_scale: float = 10.
     """
-    UASTC RDO max smooth block error scale. Range is [1,300].
+    UASTC LDR 4x4: RDO max smooth block error scale. Range is [1,300].
     Default is 10.0, 1.0 is disabled. Larger values suppress more
     artifacts (and allocate more bits) on smooth blocks.
     """
 
     uastc_rdo_max_smooth_block_std_dev: float = 18.
     """
-    UASTC RDO max smooth block standard deviation. Range is
+    UASTC LDR 4x4: RDO max smooth block standard deviation. Range is
     [.01,65536.0]. Default is 18.0. Larger values expand the range of
     blocks considered smooth.
     """
 
     uastc_rdo_dont_favor_simpler_modes: bool = False
-    """Do not favor simpler UASTC modes in RDO mode."""
+    """UASTC LDR 4x4: Do not favor simpler UASTC modes in RDO mode."""
 
     uastc_rdo_no_multithreading: bool = False
-    """Disable RDO multithreading (slightly higher compression, deterministic)."""
+    """UASTC LDR 4x4: Disable RDO multithreading (slightly higher compression, deterministic)."""
 
     # UASTC HDR params
 
diff --git a/interface/python_binding/pyktx/ktx_texture.py b/interface/python_binding/pyktx/ktx_texture.py
index 986ca042a7..8ea919890b 100644
--- a/interface/python_binding/pyktx/ktx_texture.py
+++ b/interface/python_binding/pyktx/ktx_texture.py
@@ -79,9 +79,14 @@ def base_depth(self) -> int:
 
         return lib.PY_ktxTexture_get_baseDepth(self._ptr)
 
+    # A colon in a docstring indicates the preceding text is the type. There is
+    # no way to escape it. See https://github.com/sphinx-doc/sphinx/issues/9273.
+    # Therefore we use a MODIFIER LETTER COLON '꞉', Unicode: U+A789,
+    # UTF-8: EA 9E 89 here and in any other place we want to a colon in the
+    # description.
     @property
     def num_dimensions(self) -> int:
-        """Number of dimensions in the texture: 1, 2 or 3."""
+        """Number of dimensions in the texture꞉ 1, 2 or 3."""
 
         return lib.PY_ktxTexture_get_numDimensions(self._ptr)
 
@@ -99,7 +104,7 @@ def num_levels(self) -> int:
 
     @property
     def num_faces(self) -> int:
-        """Number of faces: 6 for cube maps, 1 otherwise."""
+        """Number of faces꞉ 6 for cube maps, 1 otherwise."""
 
         return lib.PY_ktxTexture_get_numFaces(self._ptr)
 

From fb808b83f115204585c62a331b85571fe6eadd32 Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 18:26:37 +0900
Subject: [PATCH 11/13] Add UASTC_HDR_6x6_INTERMEDIATE.

---
 interface/python_binding/pyktx/ktx_supercmp_scheme.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/interface/python_binding/pyktx/ktx_supercmp_scheme.py b/interface/python_binding/pyktx/ktx_supercmp_scheme.py
index e7634171f2..00ca13ee2a 100644
--- a/interface/python_binding/pyktx/ktx_supercmp_scheme.py
+++ b/interface/python_binding/pyktx/ktx_supercmp_scheme.py
@@ -18,3 +18,6 @@ class KtxSupercmpScheme(IntEnum):
 
     ZLIB = 3
     """ZLIB supercompression."""
+
+    UASTC_HDR_6x6_INTERMEDIATE = 4
+    """UASTC HDR 6x6 Intermediate supercompression."""

From 5f396c7f1ca1bba1a37c9316bc05ba659b397298 Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 18:27:08 +0900
Subject: [PATCH 12/13] Add test of HDR compression.

---
 .../python_binding/tests/test_ktx_texture2.py   | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/interface/python_binding/tests/test_ktx_texture2.py b/interface/python_binding/tests/test_ktx_texture2.py
index 707f22c5c5..7100183ca7 100644
--- a/interface/python_binding/tests/test_ktx_texture2.py
+++ b/interface/python_binding/tests/test_ktx_texture2.py
@@ -99,9 +99,26 @@ def test_compress_basis_with_params(self):
         texture.compress_basis(KtxBasisParams(codec=KtxBasisCodec.UASTC_LDR_4x4,uastc_rdo=True))
 
         self.assertEqual(texture.color_model, KhrDfModel.UASTC)
+        self.assertEqual(texture.color_model, KhrDfModel.UASTC_LDR_4x4)
         self.assertEqual(texture.is_compressed, True)
         self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.NONE)
 
+    def test_compress_basis_hdr(self):
+        test_ktx_file = os.path.join(__test_images__, 'ktx2/Desk_small_zstd_15.ktx2')
+        texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)
+
+        self.assertEqual(texture.color_model, KhrDfModel.RGBSDA)
+        self.assertEqual(texture.is_compressed, False)
+        self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.NONE)
+
+        texture.compress_basis(KtxBasisParams(codec=KtxBasisCodec.UASTC_HDR_6x6_INTERMEDIATE,
+                                              uastc_hdr_lambda=100.,
+                                              uastc_hdr_level=3))
+
+        self.assertEqual(texture.color_model, KhrDfModel.UASTC_HDR_6x6)
+        self.assertEqual(texture.is_compressed, True)
+        self.assertEqual(texture.supercompression_scheme, KtxSupercmpScheme.UASTC_HDR_6x6_INTERMEDIATE)
+
     def test_transcode_basis(self):
         test_ktx_file = os.path.join(__test_images__, 'ktx2/color_grid_blze.ktx2')
         texture = KtxTexture2.create_from_named_file(test_ktx_file, KtxTextureCreateFlagBits.LOAD_IMAGE_DATA_BIT)

From 834071681fd5ef5ad73a8efae2b622d82720db8d Mon Sep 17 00:00:00 2001
From: Mark Callow <github@callow.im>
Date: Thu, 19 Mar 2026 18:35:51 +0900
Subject: [PATCH 13/13] Add small HDR file for pyktx tests.

---
 tests/resources/genktx2                      | 2 ++
 tests/resources/ktx2/Desk_small_zstd_15.ktx2 | 3 +++
 2 files changed, 5 insertions(+)
 create mode 100644 tests/resources/ktx2/Desk_small_zstd_15.ktx2

diff --git a/tests/resources/genktx2 b/tests/resources/genktx2
index 485e71be58..fad242a4ba 100755
--- a/tests/resources/genktx2
+++ b/tests/resources/genktx2
@@ -141,3 +141,5 @@ $ktx convert --testrun -t ktx ktx/pattern_02_bc2.ktx ktx2/pattern_02_bc2.ktx2
 # HDR images
 $ktx create --testrun --format R16G16B16_SFLOAT --encode uastc-hdr-4x4 --uastc-hdr-ultra-quant --zstd 15 input/exr/Desk.exr ktx2/Desk_uastc_hdr4x4_zstd_15.ktx2
 $ktx create --testrun --format R16G16B16_SFLOAT --encode uastc-hdr-6x6i --uastc-hdr-lambda 300 input/exr/Desk.exr ktx2/Desk_uastc_hdr6x6i.ktx2
+# Small uncompressed file for the pyktx tests.
+$ktx create --testrun --format R16G16B16_SFLOAT --scale 0.25 --zstd 15 input/exr/Desk.exr ktx2/Desk_small_zstd_15.ktx2
diff --git a/tests/resources/ktx2/Desk_small_zstd_15.ktx2 b/tests/resources/ktx2/Desk_small_zstd_15.ktx2
new file mode 100644
index 0000000000..7528b3b9b4
--- /dev/null
+++ b/tests/resources/ktx2/Desk_small_zstd_15.ktx2
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d2337d10de15d343f360511a9f055741b81c7f46b5364249ee16b25f6c4df324
+size 194396