ReadImageData, WriteImageData: take ReadSeeker or WriteSeeker and rewrite completely. Scanner, Dumper: don't stop at SOS, operate on image data too. Improve some comments.
ReadImageData, WriteImageData: take ReadSeeker or WriteSeeker and rewrite completely. Scanner, Dumper: don't stop at SOS, operate on image data too. Improve some comments.

garyhouston/jpegsegs