usage: djpeg [switches] [inputfile]
Switches (names may be abbreviated):
  -colors N      Reduce image to no more than N colors
  -fast          Fast, low-quality processing
  -grayscale     Force grayscale output
  -rgb           Force RGB output
  -scale M/N     Scale output image by fraction M/N, eg, 1/8
  -bmp           Select BMP output format (Windows style)
  -gif           Select GIF output format
  -os2           Select BMP output format (OS/2 style)
  -pnm           Select PBMPLUS (PPM/PGM) output format (default)
  -targa         Select Targa output format
Switches for advanced users:
  -dct int       Use integer DCT method (default)
  -dct fast      Use fast integer DCT (less accurate)
  -dct float     Use floating-point DCT method
  -dither fs     Use F-S dithering (default)
  -dither none   Don't use dithering in quantization
  -dither ordered  Use ordered dither (medium speed, quality)
  -map FILE      Map to colors used in named image file
  -nosmooth      Don't use high-quality upsampling
  -onepass       Use 1-pass quantization (fast, low quality)
  -maxmemory N   Maximum memory to use (in kbytes)
  -outfile name  Specify name for output file