I think this could be avoided by using some simple-stupid metric for measuring the difference between the compressed and uncompressed images and rejecting the c

I think this could be avoided by using some simple-stupid metric for measuring the difference between the compressed and uncompressed images and rejecting the compressed one if it's too different. Maybe something like dividing the image into small squares, computing the L2 difference between original and compressed. If any square has too large L2 difference then compression failed. Th metric might need to be informed by the domain. Edit: Or maybe PSNR+SSIM?