Module for seam blending after data gets stitched

httomolib/misc/blend.py

@@ -0,0 +1,128 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# ---------------------------------------------------------------------------
+# Copyright 2023 Diamond Light Source Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ---------------------------------------------------------------------------
+# Created By  : Tomography Team at DLS <scientificsoftware@diamond.ac.uk>
+# Created Date: 30 April 2026
+# ---------------------------------------------------------------------------
+"""Module for data blending functions"""
+
+import numpy as np
+from typing import Optional
+
+from httomolib.misc.utils import (
+    __check_variable_type,
+    __check_if_data_3D_array,
+    __check_if_data_correct_type,
+)
+
+__all__ = [
+    "seam_blend_stitched_data",
+]
+
+
+def seam_blend_stitched_data(
+    data: np.ndarray,
+    seam_index: Optional[int] = None,
+    blending_width: Optional[int] = None,
+    path_to_stiched_params_file: Optional[str] = None,
+    shift_seam_index: int = 0,
+) -> np.ndarray:
+    """
+    Function blends the seam present in the stitched projection data. It uses the redundant by blending_width data present on both sides of the seam.
+    Used in HTTomo for seamless stitching of datasets coming from two different PCO cameras.
+
+    Parameters
+    ----------
+    data : np.ndarray
+        3d array of the stitched data, assuming the following axis ["angles", "detY", "detX"].
+    seam_index : Optional, int
+        The horizontal index of the seam along the 'detX' axis. If None and 'path_to_stiched_params_file' is provided, it will be taken from the file, otherwise middle of the horizontal axis.
+    blending_width : Optional, int
+        The area for symmetric blending (e.g. with the ramp filter) around the seam position (seam_index) of the stitched data. If None and 'path_to_stiched_params_file' is provided, it will be taken from the file, otherwise 0.
+    path_to_stiched_params_file : Optional, str
+            Path to the text file with the stiching parameters. If provided 'seam_index' and 'blending_width' parameters will be overridden by the ones provided in the file.
+    shift_seam_index : int
+        performs a shift of the seam index with seam_index - shift_seam_index. This is purely an HTTomo related feature and should be ignored by users. 
+    Raises
+    ----------
+        ValueError: When data is not 3D.
+
+    Returns
+    ----------
+        np.ndarray: stitched data without the seam.
+    """
+    ### Data and parameters checks ###
+    methods_name = "seam_blender"
+    __check_if_data_3D_array(data, methods_name)
+    __check_if_data_correct_type(
+        data,
+        accepted_type=["float64", "float32", "uint8", "uint16", "uint32"],
+        methods_name=methods_name,
+    )
+    __check_variable_type(seam_index, [int, type(None)], "seam_index", [], methods_name)
+    __check_variable_type(
+        blending_width, [int, type(None)], "blending_width", [], methods_name
+    )
+    __check_variable_type(
+        path_to_stiched_params_file,
+        [str, type(None)],
+        "path_to_stiched_params_file",
+        [],
+        methods_name,
+    )
+    ###################################
+
+    angles_dim, detY, detX = data.shape
+
+    if path_to_stiched_params_file is not None:
+        params = {}
+        with open(path_to_stiched_params_file) as f:
+            for line in f:
+                key, value = line.split()
+                params[key] = int(value)
+
+        blending_width = params.get("blending_width")
+        seam_index = params.get("seam_index")
+
+    if blending_width is None:
+        blending_width = 0
+    if seam_index is None:
+        seam_index = int(detX // 2)
+
+    blending_width *= 2
+    seam_index -= shift_seam_index
+
+    if seam_index >= detX - blending_width:
+        err_str = f"Seam index given as '{seam_index}' must be smaller than the horizontal dimension of the data '{detX}' minus blending width."
+        raise ValueError(err_str)
+
+    # Split regions of data
+    left_part = data[:, :, 0 : (seam_index - blending_width)]
+    right_part = data[:, :, (seam_index + blending_width) : :]
+
+    # Overlap regions
+    left_overlap = data[:, :, (seam_index - blending_width) : seam_index]
+    right_overlap = data[:, :, seam_index : (seam_index + blending_width)]
+
+    # Create ramp weights (0 → 1)
+    ramp = np.float32(np.linspace(0, 1, blending_width))
+    ramp = np.tile(ramp, (detY, 1))
+
+    # Blend
+    blended_overlap = (1 - ramp) * left_overlap + ramp * right_overlap
+
+    return np.dstack([left_part, blended_overlap, right_part])

tests/conftest.py

@@ -50,6 +50,18 @@ def data_file(test_data_path):
     return np.load(in_file)
 
 
+@pytest.fixture(scope="session")
+def data_stitched(test_data_path):
+    in_file = os.path.join(test_data_path, "stitched_blend30_seam151.npy")
+    return np.load(in_file)
+
+
+@pytest.fixture(scope="session")
+def data_stitched_txt(test_data_path):
+    in_file = os.path.join(test_data_path, "stitching_params.txt")
+    return in_file
+
+
 @pytest.fixture
 def host_data(data_file):
     return np.copy(data_file["data"])

tests/test_data/stitching_params.txt

@@ -0,0 +1,2 @@
+blending_width 30
+seam_index 151

tests/test_misc/test_blend.py

@@ -0,0 +1,23 @@
+import numpy as np
+
+from httomolib.misc.blend import seam_blend_stitched_data
+
+
+def test_seam_blend_stitched_data(data_stitched):
+
+    result = seam_blend_stitched_data(data_stitched, seam_index=151, blending_width=30)
+
+    assert result.flags.c_contiguous
+    assert result.dtype == np.float32
+    assert result.shape == (300, 4, 240)
+
+
+def test_seam_blend_stitched_data_txt(data_stitched, data_stitched_txt):
+
+    result = seam_blend_stitched_data(
+        data_stitched, path_to_stiched_params_file=data_stitched_txt
+    )
+
+    assert result.flags.c_contiguous
+    assert result.dtype == np.float32
+    assert result.shape == (300, 4, 240)