Message-Id: <mailto:199409141245.HAA08390@library.wustl.edu> Date: Tue, 13 Sep 1994 18:20:45 -0400 From: "Matthew Gilmore (DC Pub. Lib)" <mailto:mgilmore@CAPCON.NET> Subject: Re: 8-bit vs. 24-bit color To: Multiple recipients of list IMAGELIB <mailto:IMAGELIB@ARIZVM1.BITNET>
I hate to just interject here, but... what about black and white images? Would it make sense to go with 24 bit or 8?Matthew Gilmore mailto:mgilmore@capcon.net
According to Pamela Mason: . . On Tue, 13 Sep 1994, Nick Cahill wrote: . . > Although an 8-bit color file is only 1/3 the size of a 24-bit file, only . > 24-bit color images can be compressed using JPEG. A JPEG-compressed 24-bit . > file is considerably smaller than an 8-bit image -- by a factor of three to . > five. And it looks just as good if not better, IMHO. If file size is an . > issue (and when isn't it?) then I'd go with compressed 24-bit images every . > time. . > . > Nick Cahill . > Dept. of Art History . > Univ. of Wisconsin-Madison . . I agree, Nick. I've been weighing what to use on the CD version of an . imaging project, and I 've pretty much decided to go with JPEG for just . that reason. The image file sizes I was comparing were: . 1.8 MB Original 24-bit color TIFF image (512x768) . 857K Compressed (Lossless LZW) 24-bit color file . 404K Tiff 8-bit color (uncompressed) . 268K Tiff 8-bit color compressed with LZW . 205K JPEG (JFIF type) 24-bit color, compressed at quality level 2 (highest) . 89K GIF (which is 8-bit color and uses a variant of LZW compression) . . As soon as you zoom in on the GIF file in comparison with the JPEG file, . the quality difference is dramatic (GIF does not handle this well), but the . TIFF 8-bit, JPEG, and LZW compressed 24-bit color all appear about the . same. With the JPEG, however, you've retained the 24-bit color . characteristics. Naturally, this is not an archival quality image. That . will be retained for all the usual reasons. . . . Pamela . *ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ* . | Pamela Mason, Project Manager | National Agricultural Library | . | mailto:pmason@nalusda.gov | Information Systems Division | . | Phone: (301) 504-6813 | 10301 Baltimore Blvd. | . | Phone: (301) 504-7473 | Beltsville, MD 20705-2351 | . *ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ*ÿ* .
Matthew Gilmore mailto:mgilmore@capcon.net
D.C. Public Library Washingtoniana Division 202.727.1213
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