Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!216.196.98.146.MISMATCH!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!novia!news-out.readnews.com!news-xxxfer.readnews.com!panix!not-for-mail From: JohnF Newsgroups: comp.graphics.algorithms Subject: Re: decorative random colors algorithm Date: Thu, 5 Jul 2012 03:18:25 +0000 (UTC) Organization: PANIX Public Access Internet and UNIX, NYC Lines: 40 Message-ID: References: <34b5c6a0-c79e-4a8f-bf71-4d480c9a5dc3@googlegroups.com> NNTP-Posting-Host: panix3.panix.com X-Trace: reader1.panix.com 1341458305 18515 166.84.1.3 (5 Jul 2012 03:18:25 GMT) X-Complaints-To: abuse@panix.com NNTP-Posting-Date: Thu, 5 Jul 2012 03:18:25 +0000 (UTC) User-Agent: tin/2.0.0-20110823 ("Ardenistiel") (UNIX) (NetBSD/5.1.2 (i386)) Xref: csiph.com comp.graphics.algorithms:926 gernot.hoffmann@hs-emden-leer.de wrote: > John, > > as stated in my doc, I'm not the inventor of the HLStoRGBf-algorithm. > 'f' stands for 'Foley,van Dam, Computer Graphics' (famous book), and > I had coded this in several programming languages, even Intel Assembly. Sorry for the misattribution. I saw your pascal comment about that, but didn't quite appreciate that it referred to the particular algorithm rather than to the general mathematics. > On the other hand, I had recognized early, that this color space > suffers much from a disadvantage: The saturation on the surface of > the double cone is S=1. On the vertical axis we have S=0. Near to poles > we have in vicinity S=1 and S=0, which is in my opinion a not acceptable > discontinuity. In order to resolve this problem I had developed my own > HLS space, which uses S as a true cylinder coordinate - small S for > small radius. At that time, trigonometric functions were sufficiently > fast, using the standard floating point unit. Okay, I'll add your Section 8 code to my C function, along with an option to use either the "standard" or "hoffmann" method (yours will become the default, of course:). > Mainly, I wanted to clarify, that I'm not the inventor of the tricky > algorithm. Right. I always try to be very careful giving credit where credit is due (sometimes even where it's not due). It's very embarrassing to look like you're claiming credit for someone else's work. Sorry for reading your hlscone doc too carelessly to realize the correct attribution. > Thanks for the interesting discussion! > Best regards --Gernot Hoffmann Thank you very much for originally providing the ps line interpolation code, and now pointing out the hls model and providing that code, too. -- John Forkosh ( mailto: j@f.com where j=john and f=forkosh )