[comp.compression] Q-Coders

raymond@cosc.canterbury.ac.nz (R P Wilson ) (05/08/91)

OK compressor heads, who can tell me roughly what sort of speed improvement
a binary alphabet fax image compressor will gain if it starts using a Q-coder
to quantise values to powers of 2 (and gets rid of a multiply per compressed
bit and a divide per decompressed bit)?

How much extra overhead would there be involved in doing this?

On a Sun 4/490 this code compresses a fine mode fax (1728x2376) in 35 seconds
and decompresses it in 55 seconds.

Raymond.

--
Raymond Wilson.	email:	raymond@cosc.canterbury.ac.nz
		snail:	c/- Computer Science Department,
			University of Canterbury,
			New Zealand.