a new technology i'd like to see created

[Skaperen]

a new technology i'd like to see created is a visual checksum for images. it would be like checksums such as md5 and sha256. it would output a hash string for an image such that separate checksums for separate copies of the same image, possibly in different lossy formats (not too lossy, as good as people find acceptable), possibly in different sizes, which will be the same for "likely" the same image. that is, if the checksums are different, the images are "most likely" different and other comparisons (that may be more expensive to do and/or need the actual image files to do their comparison) are not worth pursuing. better algorithms will have lower false positive (matched sums when they should be different) and lower false negative (mismatched sums when they should be the same).