Tom wrote:
>I would assume that LZW is a sort of runlength encoding or otherwise
>non-destructive compression. There is no reason not to use it.
LZW is the same compression used in ZIP archives. It is lossless.
> Otherwise I believe GIF is a compressed bitmap format.
> You don't loose any quality by exporting to GIF, but
> your files get significantly smaller than with TIFF/BMP.
Not exactly. GIF only allows 256 colours or 256 shades of grey. It uses
(I think) LZW compression internally so it is lossless as far as editing
is concerned but if you save a 24bit image to a GIF you *WILL* lose colour
data. GIFs are significantly smaller because you are going from 3 colour
channels to 1.
LZW TIFF is the only lossless compressed format which is understood by most
editing software. Another one is PNG but this is less widely supported.
I always use LZW TIFF for storing colour images which I may want to edit.
If I am making graphics for a web site, photos become jpegs, and line drawings
or text become GIFs. The most compact format for web display of B&W photos
is greyscale jpeg.
Rob
Rob Geraghty harper@wordweb.com
