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: November 6, 2025
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: November 6, 2025
