Would it be possible to use sha256 or sha3 instead? If needed I could probably find C implemetations of them for you.
md5 is considered broken by security experts :S
Also, I saw that you include a CRC for the captured screenshots. Would it be possible to change that to sha256 or sha3 instead too? (It’s very easy to find collisions for CRC, particularly when it comes to JPEG :S)