- From: Chris Lilley <chris@w3.org>
- Date: Tue, 15 Nov 2011 16:19:02 +0100
- To: Christoph Päper <christoph.paeper@crissov.de>
- CC: W3C Style <www-style@w3.org>, Kevin Bortis <kevin@bortis.ch>
On Tuesday, November 15, 2011, 3:56:58 PM, Christoph wrote: >> The transformation from CIE-L*C*h to CIE-L*a*b: >> L = L a = C * cos(h) b = C * sin(h) >> L = L C = sqrt(a^2+b^2) h = arctan(b/a) >> "RAL Design(TM)". The values printed on the cards are in the format >> HLC which is a lot easier to use in practice than LCh. CP> HLC seems fine enough. It is reminiscent of HSL, though, Actually, the other way round. Historically, CIE Lab and LCHab were standardised in 1976; HSL and HSV were attempts to get the same polar formulation in RGB space (but with attendant problems that L and V are not independent of H, H is not perceptually even, etc). I believe that the original proposal for HSL mentioned explicitly that it was inspired by LCHab. -- Chris Lilley Technical Director, Interaction Domain W3C Graphics Activity Lead, Fonts Activity Lead Co-Chair, W3C Hypertext CG Member, CSS, WebFonts, SVG Working Groups
Received on Tuesday, 15 November 2011 15:19:06 UTC