Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!nrl-cmf!ukma!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!hpgrla!paulc
From: paulc@hpgrla.HP.COM (@Paul Charlton)
Newsgroups: comp.graphics
Subject: Re: GIF file format
Message-ID: <4180015@hpgrla.HP.COM>
Date: 7 Feb 89 16:11:35 GMT
References: <1125@media.UUCP>
Organization: Hewlett-Packard, Greeley, CO
Lines: 21

> Unfortunately, the document does not specify anywhere what is meant by
>"Color Resolution."  It does not appear to mean what comes to mind, i. e.
>color resolution of 0 implying 2 ** 1 colors, 1 meaning 2 ** 2 ...
>This poses no problem in reading a GIF file, as all necessary information is
>provided elsewhere but it remains unclear what value to enter into this
>field when writing out an image.
>
>I would appreciate any clarification I can get.

	"pixel + 1" is the number of bits used as a palette index
	ie: if (pixel == 4), the picture uses 32 colors.

	the "color resolution" is an indication of how many bits
	are in each palette slot, for 24 bit color, the
	"color resolution" is (8 - 1) = 7
	for 12 bit color, the "color resolution" is (4 - 1 ) = 3


 PaulC

 { paulc@hpgrai.hp.com } | { hplabs!hpgrai!paulc }