KeatonMill

16th November 2002 14:14 UTC

HSV to RGB
Hey guys, I'm working on some presets which I would like to use the HSV colorspace instead of RGB. However, AVS doesn't support HSV in the superscope code. I have searched on Google for an AVS-friendly algorithm, but I haven't been able to find one.

Does anyone know of a (relatively) easy way to convert between colorspaces?

Thanks

Montana

16th November 2002 15:57 UTC

i use this, it's a method that unconed posted here in the forums:

hue=var; // (0..2PI)
sat=var; // (0..1)
lum=var; //
use any value to light/darken the color, recomended value (-1..1)
red=(sin(hue)+1)*sat*0.5+lum;
green=(sin(hue+2.09)+1)*sat*0.5+lum;
blue=(sin(hue+4.18)+1)*sat*0.5+lum;

dirkdeftly

17th November 2002 06:21 UTC

Assuming red, green, blue, hue, luminosity, and saturation are all values from 0 to 1:

red=|sin hue*pi*2)|*saturation/2+luminosity;
green=|sin hue*pi*2+pi/3)|*saturation/2+luminosity;
blue=|sin hue*pi*2+pi/3*2)|*saturation/2+luminosity;

Fast version for AVS:

init: tpi=acos(-1)*2; pit=tpi/6; tpit=pit*2;

pixel:
sat2=sat/2;
red=abs(sin(hue*tpi))*sat2+lum;
green=abs(sin(hue*tpi+pit))*sat2+lum;
blue=abs(sin(hue*tpi+tpit))*sat2+lum;

jheriko

17th November 2002 17:10 UTC

For a slightly faster version use sat2=sat*0.5;

dirkdeftly

17th November 2002 21:51 UTC

Oh, and hue2=hue*tpi;

Zevensoft

18th November 2002 10:12 UTC

Here's what I use (I don't think it's accurate, but it does the job).

Init

pi=acos(-1);tt=2/3;

red=((.5+sin((h+tt)*pi)*.5)*s+(.5+sin(h*pi)*.5)*(1-s)+(.5+sin((h-tt)*pi)*.5)*(1-s))*br;
green=((.5+sin(h*pi)*.5)*s+(.5+sin((h+tt)*pi)*.5)*(1-s)+(.5+sin((h-tt)*pi)*.5)*(1-s))*br;
blue=((.5+sin((h-tt)*pi)*.5)*s+(.5+sin(h*pi)*.5)*(1-s)+(.5+sin((h+tt)*pi)*.5)*(1-s))*br;