|AWARE [SYSTEMS]||Imaging expertise for the Delphi developer|
|TIFF and LibTiff Mailing List Archive|
LibTiff Mailing List
1997.05.08 21:06 "Re: CCITT Group 4 compression and 256 Colors", by Daniel Mccoy
Look, everybody on the list is telling you that trying to compress a color image with Group 4 compression is a BAD idea. The software is kind enough to tell you that it's a BAD idea. There are plenty of other compression schemes available for color images. I, too, would suggest you use one. But if you are hell bent on compressing your 8-bit image with Group 4 you have to either convert it to a black and white image or tell the library that it is eight times wider and set bitspersample to 1. Sheesh! Enough already. Dan McCoy >It's me again. I am stuck with a problem. In my previous mails, I had >enquired about this problem and I had got quite a few responses. >However, I am facing a problem right now and I am in need of the solution >urgently. > >The problem is that when libtiff is used, and the image being created uses >Group 4 compression, then it does not convert to TIFF file. It gives a >message >"For Group 3/4 compression, bits per sample must be 1". >However, bits/samples is 4/8 for color images as provided by the TIFF 6.0 >specs. Also, specs says that the Group 4 compression can be used only for >bilevel, and not for the color images. In this situation, can I compress >the image using Group 4 compression ? >Also, is there any way out on this perticular situation ? > >Also, one of the responses received by me last time suggested that this is >possible, but the compressed image size is very large compared to the >original image size. But I feel that is NOT the better alternative.