- From: Dave J Woolley <DJW@bts.co.uk>
- Date: Fri, 4 Feb 2000 11:52:23 -0000
- To: www-html@w3.org
> From: rev-bob@gotc.com [SMTP:rev-bob@gotc.com] > > > and JPG and GIF are coded for screen or RGB (Red, Green, Blue). > > That's accurate, at least as far as I can attest. > JPEG is normally internally coded as YUV (intensity and two colour components, as used in colour TV - the colour components are normally recorded with lower resolution than the intensity component). > True animation (multiple frames): GIF and PNG, but not TIFF, BMP, or JPG. > I wasn't aware that PNG permitted animation. TIFF allows multiple frames per file, even if no browser animates them (this is normal case for TIFF fax images, as viewed by Wang/ Kodak/Eastman Imaging in Windows). > Lossless data storage: All but JPG. > The palletisation process in GIF is lossy, although the losses don't accumulate if the image is reprocessed. (With dithering one even trades spacial resolution for colour resolution.) > High color range: All but GIF, which is limited to 256 different colors at > most. > Simple transparency (one color): GIF and PNG only. > Complex transparency (shades): Multi-channel PNG only, map stored in alpha > channel. > Also XCF, the native GIMP format. This also supports animation and layered images. > Smallest image size (complex image): JPG. > Natural scenes, not complex images. > Largest image size (any image): TIFF/BMP. > TIFF files can be JPEG or LZW encoded, so this statement is only true of a sub-class of TIFF. In fact, for black and white text scans, TIFF with Group 4 FAX encoding is probably the best format.
Received on Friday, 4 February 2000 06:58:49 UTC