simonw / image-diff Goto Github PK

I'm assuming this is a fault on my end that the core functionality does not work outright or I'm misunderstanding something. I've created a virtual environment, installed image-diff, and am trying to produce a differential image exactly as in the documentation, but the resulting image is seemingly empty. I've tried using both PNG and JPG as the input image formats, but it makes no difference.

Here are the two images I'm using just so that we're on the same page and here is the supposed differential between the two.

I'm using Python 3.10.7 on Fedora 36.

While trying to write tests for #1 I found it surprisingly hard to create test PNG images exactly how I wanted them.

This command. will let me compile an image from a JSON description.

This here:

[
   [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]],
   [[0, 0, 0], [255, 0, 0], [0, 0, 0], [0, 0, 0]],
   [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]
]

Produced this image:

This is a crufty way of doing that which seems to work:

len([p for p in diff.getdata() if p != (0, 0, 0)])

My original inspiration for this tool was that I wanted to run a CI job that checked if an image had changed by more than a certain amount.

A command that varies its exit code based on the size of the difference could solve this.