Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!204.52.135.9.MISMATCH!newsfeed.hal-mli.net!feeder1.hal-mli.net!69.16.185.11.MISMATCH!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!nx02.iad01.newshosting.com!newshosting.com!news-out.readnews.com!transit3.readnews.com!panix!not-for-mail From: JohnF Newsgroups: comp.graphics.algorithms Subject: Re: decorative random colors algorithm Date: Mon, 2 Jul 2012 08:28:49 +0000 (UTC) Organization: PANIX Public Access Internet and UNIX, NYC Lines: 55 Message-ID: References: NNTP-Posting-Host: panix3.panix.com X-Trace: reader1.panix.com 1341217729 5358 166.84.1.3 (2 Jul 2012 08:28:49 GMT) X-Complaints-To: abuse@panix.com NNTP-Posting-Date: Mon, 2 Jul 2012 08:28:49 +0000 (UTC) User-Agent: tin/2.0.0-20110823 ("Ardenistiel") (UNIX) (NetBSD/5.1.2 (i386)) X-Received-Bytes: 3488 Xref: csiph.com comp.graphics.algorithms:907 Nobody wrote: > On Sun, 01 Jul 2012 12:15:11 +0000, JohnF wrote: > >> However, it still looks a bit "washed out" to my eye. But pushing the >> exponents (1/3 and 2) too much just "degenerates" the palette to rgb. >> So maybe my whole idea is just no good. Is there some standard, >> or not-so-standard, way to choose random rgb numbers that both >> (a) remain pretty much random, and that also (b) make the resulting >> image more "vibrant" to the eye (whatever that quantitatively means; >> I can tell what it subjectively means just by looking)? > > IOW, you want more saturation. Using an HSL or HSV colour space is one > solution. > > http://en.wikipedia.org/wiki/HSL_and_HSV Thanks so much for the useful reference (and the keywords, which probably would have induced google to cough up more useful info than I was able to wring out of it myself). Along with Prof. Hoffmann's http://www.fho-emden.de/~hoffmann/hlscone03052001.pdf from the preceding followup, that pretty much explains the situation in terms I can understand. > If you just want maximum saturation, an alternative is to modify your > original approach. Set the largest to 1, the smallest to 0, and leave the > middle one alone. That will give you a uniformly-distributed point on the > path: > > Red - Yellow - Green - Cyan - Blue - Magenta - Red > > i.e. all of the edges of the RGB colour cube which don't have black or > white as an endpoint. > > The original approach doesn't have quite as much saturation (the highest > and lowest are moved closer to 1.0 and 0.0 rather than all the way), > while moving the middle one closer to zero results in a bias toward > red, green and blue. That sounds perfect and easy, so I tried it out (but it was hard to write a comment crediting you for the suggestion -- I was tempted to thank Emily Dickinson:). You can see the results at http://www.forkosh.com/decorative.ps [original] http://www.forkosh.com/decorative2.ps [your suggestion] (Note: if you already downloaded the original, re-download it, as one line is now placed slightly differently -- the %%title is supposed to contain all parameters to reproduce exactly the same design, but I slightly goofed.) Doesn't seem to have much effect on the visual outcome (though you can diff the two files and easily validate everything's working as advertised). On the other hand, the illustrations in Prof. Hoffmann's hlscone section 5 don't show much visual difference either, so perhaps I'm just expecting too much improvement. Thanks so much for your help, -- John Forkosh ( mailto: j@f.com where j=john and f=forkosh )