An aside:
djpeg -dct int -dither none -outfile
The_Garden_of_Earthly_Delights_by_Bosch_High_Resolution.int.pnm
The_Garden_of_Earthly_Delights_by_Bosch_High_Resolution.jpg
djpeg -dct float -dither none -outfile
The_Garden_of_Earthly_Delights_by_Bosch_High_Resolution.float.pnm
The_Garden_of_Earthly_Delights_by_Bosch_High_Resolution.jpg
pamarith -difference The_Garden_of_Earthly_Delights_by_Bosch_High_Resolution.int.pnm
The_Garden_of_Earthly_Delights_by_Bosch_High_Resolution.float.pnm| pamtopnm -plain | awk
'NR>3 { for (i = 1; i <= NF; i++) if ($i > max) max = $i } END { print max }'
yields 3. So though the modulus of the difference is small (and probably
invisible unless the images are hugely magnified), it's not 0 or 1 on this
example.
