tom@cuff.uucp (Tom Flaherty) (03/26/91)
Does anyone have or can anyone point me to a fast algorithm for decompressing CCITT Group 4 data? Does anyone know of any references for compression /decompression techniques? Thanks, Tom Flaherty
jgro@lia (Jeremy Grodberg) (03/27/91)
In article <1991Mar25.210709.21316@cuff.uucp> tom@cuff.uucp (Tom Flaherty) writes: > > Does anyone have or can anyone point me to a fast > algorithm for decompressing CCITT Group 4 data? > Does anyone know of any references for compression > /decompression techniques? The Group 4 spec can be found in CCITT Fascicle VII.3 - Rec. T.6. Unfortunately, I don't know where to get it. Maybe Global Engineering Documents in Southern California (Irvine?). Sun sells some fair code for decompressing Group 4 compressed Data. I've seen a number of proprietary implementations, and they all hover around 1.25 Million pixels per second output from the decompressor on a Sun IPC. Sun's code is considerably slower, but I don't have any good figures on exactly how much. The speed of the decompression is largely based on how effectively it utilizes the computer's native bit instructions, memory I/O, and caching architecture, so you may well find that a "wicked fast" piece of code on one machine is a real dog on another. For example, Sun's code is slow on a SPARC machine, but may very well be fast on a Sun-3 (Motorola 680X0) machine (I haven't tried). -- Jeremy Grodberg "Show me a new widget that's bug-free, and I'll show jgro@lia.com you something that's been through several releases."
cisneros@cs.ucf.edu (Jaime Cisneros) (04/03/91)
Newsgroups: comp.compression
Subject: Image Compression of a TARGA TYPE 10 file format
Summary:
Expires:
References:
Sender: cisneros@eola.cs.ucf.edu
Followup-To: anyone who can help
Distribution: na
Organization: University of Central Florida, Orlando
Keywords: TARGA TYPE 10 file format
To whomever that could help on this,
I am trying to do some image compression on a TARGA TYPE 10 file format.
The image is 128x128, and I would like to compress it down to 64x64. I would
like to get my hands on a piece of source code to do the image compression.
Please if there is someone who knows how to do that, send me the
piece of source code to look at, and learn (I will be very thankful).
By the way, I am a student trying do something extra for a class.
Jaime Cisneros
E-mail: cisneros@eola.cs.ucf.edu