If these are JPEGs with a grey or green lower half, it's likely only a few 16x16 macroblocks are corrupted and you can recover the rest.
This cannot be done programmatically because you have to guess what the average colour of the block was, but it can be worth it for precious pictures.
With JPEG one of the big problems is that the data is Huffman-encoded without any inter-block markers (except maybe Restart Markers, if you're lucky). This means that a single bitflip can result in a code changing length, causing frameshifts in many subsequent blocks and rendering them all undecodable. If you have a large block of missing data (e.g. a 4k-byte sector of zeros), then you have to guess where in the image the bitstream resumes, in addition to guessing the value of the running DC components.