eero@media-lab.media.mit.edu (Eero Simoncelli) (06/16/91)
Archive-name: compression/wavelets/epic/1991-06-14 Archive: whitechapel.media.mit.edu:/pub/epic.tar.Z [18.85.0.125] Original-posting-by: eero@media-lab.media.mit.edu (Eero Simoncelli) Original-subject: Re: JPEG obsolete Reposted-by: emv@msen.com (Edward Vielmetti, MSEN) For those of you interested in Wavelet compression schemes, I have a very fast (on the decompression end) pyramid wavelet coder. It works reasonably well (informal comparisons seemed noticably better than JPEG), but there is certainly room for improvement. It is available via anonymous ftp -- here is the README file: --------------------------------------------------------------------- --- EPIC (Efficient Pyramid Image Coder) --- --- Designed by Eero P. Simoncelli and Edward H. Adelson --- --- Written by Eero P. Simoncelli --- --- Developed at the Vision Science Group, The Media Laboratory --- --- Copyright 1989, Massachusetts Institute of Technology --- --- All rights reserved. --- --------------------------------------------------------------------- Permission to use, copy, or modify this software and its documentation for educational and research purposes only and without fee is hereby granted, provided that this copyright notice appear on all copies and supporting documentation. For any other uses of this software, in original or modified form, including but not limited to distribution in whole or in part, specific prior permission must be obtained from M.I.T. and the authors. These programs shall not be used, rewritten, or adapted as the basis of a commercial software or hardware product without first obtaining appropriate licenses from M.I.T. M.I.T. makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. --------------------------------------------------------------------- EPIC (Efficient Pyramid Image Coder) is an experimental image data compression utility written in the C programming language. The compression algorithms are based on a hierarchical subband decomposition using asymmetric filters (described in the references given below) and a combined run-length/Huffman entropy coder. The filters have been designed to allow extremely fast decoding on conventional (ie, non-floating point) hardware, at the expense of slower encoding. We are making this code available to interested researchers who wish to experiment with a subband pyramid coder. We have attempted to optimize the speed of pyramid reconstruction, but the code has not been otherwise optimized, either for speed or compression efficiency. In particular, the pyramid construction process is unnecessarily slow, quantization binsizes are chosen to be the same for each subband, and we have used a very simple scalar entropy coding scheme to compress the quantized subbands. Although this coding technique provides good coding performance, a more sophisticated coding scheme (such as vector quantization) using the same pyramid decomposition could result in substantial coding gains. EPIC is currently limited to 8-bit monochrome square images, and does not explicitly provide a progressive transmission capability. Epic is available via anonymous ftp from whitechapel.media.mit.edu (IP number 18.85.0.125) in the file pub/epic.tar.Z. Comments, suggestions, or questions should be sent to: Eero P. Simoncelli Vision Science Group MIT Media Laboratory, E15-385 Cambridge, MA 02139 Phone: (617) 253-3891, E-mail: eero@media-lab.media.mit.edu References: Edward H. Adelson, Eero P. Simoncelli and Rajesh Hingorani. Orthogonal pyramid transforms for image coding. In Proceedings of SPIE, October 1987, Volume 845. 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. Subband Image Coding with Three-tap Pyramids. Picture Coding Symposium, 1990. Cambridge, MA. USAGE: ------ Typing "epic" gives a description of the usage of the command: epic infile [-o outfile] [-x xdim] [-y ydim] [-l levels] [-b binsize] An example call might look like this: epic /images/lenna/data -o test.E -x 512 -y 512 -l 5 -b 33.45 Note that: 1) the infile argument must be a file containing raw image data 2) this file must be an 8 bit file (not 32 bit or float) 3) if the size of the image is different than 256x256, you must specify it on the command line. Currently, the code is limited to square images only. 4) the binsize can be any floating point number. Larger numbers give higher compression rates, smaller numbers give better image quality. Using a binsize of zero should give perfect reconstruction. 5) Color images can be compressed best by converting from rgb to yiq and compressing each of the components separately. The decompression command "unepic" is much easier to use. Typing "unepic test.E" will create a raw 8bit data file called "test.E.U". If you don't like that name, you can specify a different name as an optional second argument. -- Eero Simoncelli Vision Science Group MIT Media Laboratory, E15-385 Cambridge, MA 02139 -- comp.archives file verification whitechapel.media.mit.edu -rw-rw-r-- 1 20024 20 117599 Feb 26 19:32 /pub/epic.tar.Z found epic ok whitechapel.media.mit.edu:/pub/epic.tar.Z