PostScript level 2 and PostScript 3 support several compression algorithms. This means that pages can contain compressed images when being send to the RIP and that the RIP will handle decompression. Among the compression formats support are CCITT group 4 and JPEG. Errors mentioning DCTdecodefilter point to the RIP having problems decompressing an image.

JPEG compressed images

One of my customers reported occasional ‘DCTdecodefilter’ PostScript errors when imaging the yellow plate of large (100 MB and up) JPEG compressed images on an Agfa RIP running PSE 11. Resending only that colour always solved the problem. Resaving the files uncompressed may also be a good work-around.

OPI DCS-merging

Some OPI-systems can’t handle DCS JPEG-compressed images properly. When a queue is setup to do a DCS-merge, the OPI-system will not merge properly and a PostScript error “DCTdecodefilter” pops up on the RIP.