JPEG lossy recompressor that removes least informative scans to reach a target quality
perl jpegdropscan.pl [switches] inputfile outputfile
-d N Maximum quality metric difference level (default: 0)
-r path Path to reference image to use with quality metric evaluator (default: inputfile)
-n [N] Use quality (N = best, 100 default) rather than distance (0 = best)
-q Suppress all output
-v Verbose output
-p path Path to jpegtran (default: jpegtran)
-c path Path to quality metric evaluator (default: butteraugli)
-b 0-13 Maximum number of bit splits to test (default: 3)
- Perl
- jpegtran from libjpeg, libjpeg-turbo, or mozjpeg
- butteraugli, SSIMULACRA 2 or other quality metric evaluator
Rather than recoding an image, jpegdropscan iteratively removes scan information starting with least significant bits and moving to least significant coefficients. Originally developed using butteraugli for quality evaluation, but other metrics may be used.
Best results can be achieved by processing an image with jpegultrascan first, running jpegdropscan, then jpegultrascan once more.
Aaron Kaluszka <[email protected]>