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 EPIC(1)                                                             EPIC(1)
                                 August 1989



 NAME
      epic - efficient image pyramid coder

 SYNOPSIS
      epic imagefile [ -o epicfile ] [ -x xdim ] [ -y ydim ] [ -l levels ] [
      -b binsize ] unepic epicfile [ resultfile ]

 DESCRIPTION
      Epic compresses raw (8-bit) image files, using an asymmetrical subband
      pyramid (biorthogonal wavelet) decomposition, and a combined run-
      length/Huffman entropy coder.  Epic is a lossy coder: it introduces
      errors in the compressed image.  Unepic decompresses the files that
      have been compressed using Epic.  The required Epic argument imagefile
      must be the name of a raw 8-bit image file.  The required Unepic
      argument epicfile must be the name of a compressed file created using
      epic.


    OPTIONS:
      epicfile is the name to be used for the compressed image file.  It
      defaults to a concatenation of the imagefile name and the extensions
      ".E".  resultfile is the name of the file in which unepic puts the
      de-compressed image.  It defaults to a concatenation of the epicfile
      name and the extension ".U".  xdim is the x dimension (line length) of
      the image in pixels.  It defaults to 256.  Note that this must be
      specified if the image width is not 256!  ydim is the y dimension
      (height) of the image in pixels.  It defaults to 256.  Note that this
      must be specified if the image height is not 256!  levels specifies
      the number of recursive pyramid levels to build.  This defaults to 4
      which is appropriate for images of size 256x256.  binsize specifies
      the quantization binsize to be used in compressing the image.  This
      parameter determines the amount of compression (or the loss of
      quality). Setting it to 0 will produce the highest quality (but least
      compressed) image.


 CAVEATS
      1. Code is currently limited to square images.  2. The dimensions of
      the image must be divisible by 2^levels.  3. Color images may be
      compressed by converting from RGB space to YIQ space and compressing
      each of the components separately.


 AUTHORS
      Written by Eero P. Simoncelli and Edward H. Adelson, August, 1989.


 REFERENCES
      Edward H. Adelson, Eero P. Simoncelli.  Subband Image Coding with
      Three-tap Pyramids.  Picture Coding Symposium, 1990.  Cambridge, MA.




                                    - 1 -         Formatted:  March 28, 2024






 EPIC(1)                                                             EPIC(1)
                                 August 1989



      Eero P. Simoncelli.  Orthogonal Sub-band Image Transforms.  Master's
      Thesis, EECS Department, Massachusetts Institute of Technology. May,
      1988.

      Edward H. Adelson, Eero P. Simoncelli and Rajesh Hingorani.
      Orthogonal pyramid transforms for image coding.  In Proceedings of
      SPIE, October 1987, Volume 845.















































                                    - 2 -         Formatted:  March 28, 2024