jpegtran: must name one input and one output file
usage: jpegtran [switches] inputfile outputfile
Switches (names may be abbreviated):
  -copy none     Copy no extra markers from source file
  -copy comments Copy only comment markers (default)
  -copy all      Copy all extra markers
  -optimize      Optimize Huffman table (smaller file, but slow compression)
  -progressive   Create progressive JPEG file
Switches for modifying the image:
  -crop WxH+X+Y  Crop to a rectangular subarea
  -grayscale     Reduce to grayscale (omit color data)
  -flip [horizontal|vertical]  Mirror image (left-right or top-bottom)
  -perfect       Fail if there is non-transformable edge blocks
  -rotate [90|180|270]         Rotate image (degrees clockwise)
  -scale M/N     Scale output image by fraction M/N, eg, 1/8
  -transpose     Transpose image
  -transverse    Transverse transpose image
  -trim          Drop non-transformable edge blocks
Switches for advanced users:
  -restart N     Set restart interval in rows, or in blocks with B
  -maxmemory N   Maximum memory to use (in kbytes)
  -outfile name  Specify name for output file
  -verbose  or  -debug   Emit debug output
Switches for wizards:
  -arithmetic    Use arithmetic coding
  -scans file    Create multi-scan JPEG per script file