pngcrush optimizes the file losslessly. Looks the same, smaller file size. Since the file does change, git will see a difference (doesn't care what it looks lik

pngcrush optimizes the file losslessly. Looks the same, smaller file size. Since the file does change, git will see a difference (doesn't care what it looks like). To a user, viewing the diff through this Github feature, it would look like nothing changed between commits.