W3C home > Mailing lists > Public > public-fx@w3.org > October to December 2013

Re: [filter-effects] hue-rotate() and saturate() filters

From: Alan Gresley <alan@css-class.com>
Date: Tue, 15 Oct 2013 09:25:12 +1100
Message-ID: <525C6F48.5020402@css-class.com>
To: Chris Lilley <chris@w3.org>, Rik Cabanier <cabanier@gmail.com>
CC: Michael Mullany <michael@sencha.com>, "public-fx@w3.org" <public-fx@w3.org>
On 15/10/2013 7:23 AM, Chris Lilley wrote:
> Hello Rik,

> Incidentally these polar forms were what inspired Tektronix et al to
> come up with HSL, HSV and similar polar forms of RGB. Unlike the
> measurement-based CIE forms, however, HSL and HSV are not perceptually
> uniform and have some odd behaviour - primary blue (#00F) and secondary
> yellow (#FF0) have the same lightness in HSL and the same value in
> HSV.

Why do you say they are not perceptually uniform and have some odd 
behaviour? From my understanding, both primary blue (#00F) and secondary 
yellow (#FF0) are complementary to each other [1] but in gray-scale, 
secondary yellow is much lighter than primary blue [2] since it appears 
much higher in a sRBG cube (X,Y,Z axes) and more so if we consider that 
the sRBG cube has an orientation that is tilted on each axes (X,Y,Z) 
when considering overall gray-scale of lightness from white to black 
[3]. There is nothing odd about colour in this respect.

>> However, doing so would require a whole new set of formulas in the
>> filters specification and a lot of work in the browsers...
> Not really. In each case, you transform to the working colourspace,
> perform channelwise operations, then transform back.

1. http://css-class.com/articles/color/index.htm#yellow-blue
2. http://css-class.com/test/css/colors/hsl-in-sRGB-color-space.htm
3. http://css-class.com/test/css/colors/color-cube-grayscale.htm

Alan Gresley
Received on Monday, 14 October 2013 22:25:42 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:49:47 UTC