/usr/bin/cjpeg

usage: /usr/bin/cjpeg [switches] [inputfile]
Switches (names may be abbreviated):
  -quality N[,...]   Compression quality (0..100; 5-95 is most useful range,
                     default is 75)
  -grayscale     Create monochrome JPEG file
  -rgb           Create RGB JPEG file
  -optimize      Optimize Huffman table (smaller file, but slow compression)
  -progressive   Create progressive JPEG file
  -targa         Input file is Targa format (usually not needed)
Switches for advanced users:
  -precision N   Create JPEG file with N-bit data precision
                 (N=2..16; default is 8; if N is not 8 or 12, then -lossless
                 must also be specified)
  -lossless psv[,Pt]  Create lossless JPEG file
  -arithmetic    Use arithmetic coding
  -dct int       Use accurate integer DCT method (default)
  -dct fast      Use less accurate integer DCT method [legacy feature]
  -dct float     Use floating-point DCT method [legacy feature]
  -icc FILE      Embed ICC profile contained in FILE
  -noicc         Do not transfer ICC profile from PNG input file
  -restart N     Set restart interval in rows, or in blocks with B
  -smooth N      Smooth dithered input (N=1..100 is strength)
  -maxmemory N   Maximum memory to use (in kbytes)
  -outfile name  Specify name for output file
  -nooverwrite   Don't overwrite output file if it exists
  -memdst        Compress to memory instead of file (useful for benchmarking)
  -report        Report compression progress
  -strict        Treat all warnings as fatal
  -verbose  or  -debug   Emit debug output
  -version       Print version information and exit
Switches for wizards:
  -baseline      Force baseline quantization tables
  -qtables FILE  Use quantization tables given in FILE
  -qslots N[,...]    Set component quantization tables
  -sample HxV[,...]  Set component sampling factors
  -scans FILE    Create multi-scan JPEG per script FILE