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Re: [css3-colors] Comments on Last Call

From: Chris Lilley <chris@w3.org>
Date: Mon, 17 Feb 2003 09:24:38 +0100
Message-ID: <1371076093.20030217092438@w3.org>
To: www-style@w3.org, David Woolley <david@djwhome.demon.co.uk>

On Sunday, February 16, 2003, 9:40:04 PM, David wrote:

>> 3.1.1. Gamma correction
>> I really don't see, why details for browser implementation across OSs have
>> to be in the spec.

DW> Whilst strictly speaking they shouldn't be there, except as a
DW> non-normative appendix, this is an area that implementors are very
DW> likely to get wrong, even with it explicitly in the standard.

That is exactly why it has been in CSS ever since CSS1 (and still the
implementors get it wrong).

DW> There is widespread ignorance about gamma, certainly amongst
DW> amateurs, marketing people, and programmers writing web pages (and
DW> browsers). It is possible that some professional designers are
DW> aware, but I suspect knowledge is rare there. Only really people
DW> who specialise in colourimetry really know about it; browser
DW> programmers are likely to have little technical knowledge in this
DW> area.

Yes, agreed. And because color is complicated in general, such
programmers ignore it completely, even the brain-dead simple stuff
like gamma correction.

DW> It is very common to find gamma 1.0 or gamma 1.45 images on
DW> commercial web sites, and most amateurs distribute images out of
DW> their camera, which often have gamma 1.0, and loss of significance
DW> on some channels (typically blue and green). On the other hand
DW> very few people seem to realise that there is anything wrong with
DW> their over-dark and poorly colour balanced images!

An image with gamma 1.0 is not over dark or poorly balanced provided
it *says* it is a gamma 1.0 image.

DW> (One of the things that irritates me about image manipulation
DW> programs is their poor support of gamma; I'd like to be able to
DW> convert to gamma 1.0, adjust black and white levels, and then
DW> return to gamma 2.2, without unecessary loss of significance, but
DW> find I'm forced to to the steps individually - they really need to
DW> either accumulate a transform, or work with more colour depth than
DW> the images.)

Working with more color depth is the usual solution to this.

DW> I think every opportunity needs to be taken to stress gamma, if
DW> one is to hope for good quality images.

I agree.

DW> Incidentally, what is describe is the effect of both hardware and
DW> OS; Macs have gamma 1.45 because of their hardware, not their
DW> software.

Yes, agreed.

 Chris                            mailto:chris@w3.org
Received on Monday, 17 February 2003 03:24:41 UTC

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