usage: cjpeg [switches] [inputfile]
Switches (names may be abbreviated):
-quality N[,...] Compression quality (0..100; 5-95 is useful range)
-grayscale Create monochrome JPEG file
-rgb Create RGB JPEG file
-optimize Optimize Huffman table (smaller file, but slow compression)
-progressive Create progressive JPEG file
-scale M/N Scale image by fraction M/N, eg, 1/2
-targa Input file is Targa format (usually not needed)
Switches for advanced users:
-arithmetic Use arithmetic coding
-block N DCT block size (1..16; default is 8)
-rgb1 Create RGB JPEG file with reversible color transform
-bgycc Create big gamut YCC JPEG file
-dct int Use integer DCT method (default)
-dct fast Use fast integer DCT (less accurate)
-dct float Use floating-point DCT method
-nosmooth Don't use high-quality downsampling
-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
-verbose or -debug Emit debug output
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
