diffimg-go

Image differentiation tool like the homonymous python module.

You may find it useful for testing image processing applications/services.

Installation

go get github.com/nicolashahn/diffimg-go

Usage

$ diffimg-go [-filename=FILENAME] [-ignorealpha] IMAGE1 IMAGE2

IMAGE1 and IMAGE2 are image files. They must be the same size.

-filename=FILENAME creates a diff image at FILENAME if passed. This should have a .png extension.

-ignorealpha ignores the alpha channel for the ratio calculation, and if generating a diff image, sets the alpha value for all pixels to max. If both images are fully opaque (all the alpha channel values for all pixels in both images are the maximum value) then a simple diff (without ignorealpha) would produce a fully transparent image. Use this flag if you do not want that. It gives a different diff ratio because the calculation is now being done with 3 instead of 4 channels.

Examples

The images used in these examples are here and here.

$ diffimg-go test/data/mario-circle-cs.png test/data/mario-circle-node.png
0.002123925685759868

$ diffimg-go -ignorealpha test/data/mario-circle-cs.png test/data/mario-circle-node.png
0.0017478156325230589

$ diffimg-go -filename=diff.png test/data/mario-circle-cs.png test/data/mario-circle-node.png
0.002123925685759868
$ open diff.png

$ diffimg-go -filename=diff.png -ignorealpha test/data/mario-circle-cs.png test/data/mario-circle-node.png
0.002123925685759868
$ open diff.png