Comment Re:Which company is next in line? (Score 1) 353
They don't hash the raw file itself they construct a specialised hash based on the image content. It breaks the image up into chunks, analyses those chunks and generates a hash from that analysis. The intent being to make it resilient to cropping, scaling and colour changes. http://en.wikipedia.org/wiki/P...
The geek in me wants to know the algorithm(s) it uses so I can detect similar but not-quite-identical images in a collection. The (free) programs that I tried so far were stumped by cropping or colour changes or both.