png-cmp: like cmp for PNGs

png-cmp is a program I built that checks if two PNGs are visually equivalent. It&rsquo;s inspired by the cmp command . Here&rsquo;s how you use it: png-cmp a.png b.png Like cmp , it silently exits if the images are identical, and gives an error if they&rsquo;re different. Unlike cmp , it checks pixel data, not binary data. PNGs can look the same but be stored differently. For example, png-cmp…