imagediff

Purpose

Imagediff determines the differences between two images:

First input image	Second input image	Detected differences

You can tell it to ignore certain areas in the images. Choose some random color, cover up those areas in either of the images and supply the RGBA values of the selected color (see later how to supply the RGBA values)

First input image	Second input image	Result showing the difference

Running it as a standalone tool

It can run as a standalone commandline tool like this:

.\image-diff.exe  --img1 .\examples\test1a.png --img2 .\examples\test1b.png --output .\examples\test1-result.png

It outputs a single CSV line to the console with the input images, number of different pixels and location of output image:

.\examples\test1a.png,.\examples\test1b.png,49841,.\examples\test1-result.png

Specify the ignore color on the commandline as follows:

.\image-diff.exe  --img1 .\examples\test-ignorecolor-1.png --img2 .\examples\test-ignorecolor-2.png --output .\examples\test-ignorecolor-result.png -ignoreR 255 -ignoreG 216 -ignoreB 0

Running it as a REST service

Start the tool

The tool can also run as a REST webservice.

.\image-diff.exe
Listening on 0.0.0.0:80
#It also accepts and IP:Port argument
.\image-diff.exe -listen 10.0.0.1:1234
Listening on 10.0.0.1:1234

or run it as a container with docker

docker run -d --rm -p80:80 adrichem/image-diff:latest -listen 0.0.0.0:80

Check that its running

If you want to check whether the service is ready for use, you can GET the /status endpoint. It returns HTTP 200 when its ready for use.

Send images and check the response headers and body for results

Post the images as a multipart form. The service responds with:

1. a body containing the difference image.
2. a response header containing the number of different pixels.

Example with postman

Headers	Body

Example in C#

	var form = new MultipartFormDataContent();
	StreamContent img1 = new StreamContent(StreamToYourFirstImage);
	StreamContent img2 = new StreamContent(StreamToYourSecondImage);

	img1.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
	{
		FileName = "img1.png",
		Name = "img1",
	};
	img1.Headers.ContentType = new MediaTypeHeaderValue("image/png");
	form.Add(img1);

	img2.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
	{
		FileName = "img2.png",
		Name = "img2",
	};
	img2.Headers.ContentType = new MediaTypeHeaderValue("image/png");
	form.Add(img2);
	
	form.Add(new StringContent( "{ \"r\":255, \"g\":216, \"b\":0 }"), "ignoreColor");

	var request = new HttpRequestMessage()
	{
		RequestUri = new Uri("http://localhost/"),
		Method = HttpMethod.Post,
		Content = form,
	};