1. color difference equations
- Posted by Tone Škoda <tskoda at email.si>
Sep 29, 2004
-
Last edited Sep 30, 2004
I know there exist these color difference formulas:
CIELAB, CMC, BFD, CIE94, GLAB
but I just can't find them on the net. Can somebody help me find them?
I want to test them to find out which one is working best.
As input I want to have RGB not LUV or something like that, because finding
formulas to do conversion is also hard.
I don't know which formula this function uses, but it doesn't work good:
--// Returns difference of two colors.
--// atom between 0 and 1.
--// 0 = smallest difference
--// 1 = biggest difference
global function weighted_color_distance (COLOR color1, COLOR color2)
integer rmean
integer dr,dg,db
rmean = floor((GetRValue (color1) + GetRValue (color2)) / 2)
dr = (GetRValue (color1) - GetRValue (color2))
dr *= dr
dr = floor((dr * (512 + rmean)) / 256)
dg = (GetGValue (color1) - GetGValue (color2))
dg = (dg * dg) * 4
db = (GetBValue (color1) - GetBValue (color2))
db *= db
db = floor((db * (767 - rmean)) / 256)
return (dr + dg + db) / 584970
end function
2. Re: color difference equations
How weird.... GMail displays Google Ads pertaining to the message
you're reading. One of the 'Related Pages' links that popped up was
this: www.easyrgb.com/math which I'm sure you'll find quite useful.
~Greg
On Thu, 30 Sep 2004 00:41:35 +0200, mic _ <stabmaster_ at hotmail.com> wrote:
>
> Where did you get that code from? It looks very similar to something I wrote
> a long time ago, but I can't remember for what program.
> Anyway, you could view the two colors as 3D vectors and calculate the
> difference in length of the vectors, the angle between the vectors or some
> other measure. Or you could calculate the luma of each color and take the
> difference between those (where luma = 0.299*R + 0.587*G + 0.114*B). I bet
> there are lots of other formulaes.
>
>
> >I don't know which formula this function uses, but it doesn't work good:
> >}}}
<eucode>
> >--// Returns difference of two colors.
> >--// atom between 0 and 1.
> >--// 0 = smallest difference
> >--// 1 = biggest difference
> >global function weighted_color_distance (COLOR color1, COLOR color2)
> > integer rmean
> > integer dr,dg,db
> >
> > rmean = floor((GetRValue (color1) + GetRValue (color2)) / 2)
> > dr = (GetRValue (color1) - GetRValue (color2))
> > dr *= dr
> > dr = floor((dr * (512 + rmean)) / 256)
> >
> > dg = (GetGValue (color1) - GetGValue (color2))
> > dg = (dg * dg) * 4
> >
> > db = (GetBValue (color1) - GetBValue (color2))
> > db *= db
> > db = floor((db * (767 - rmean)) / 256)
> >
> > return (dr + dg + db) / 584970
> >end function
> ></eucode>
{{{
> >
> >
>
>
>
3. Re: color difference equations
Greg Haberek wrote:
>
> How weird.... GMail displays Google Ads pertaining to the message
> you're reading. One of the 'Related Pages' links that popped up was
> this: www.easyrgb.com/math which I'm sure you'll find quite useful.
There is some useful stuff on that site, thanks. But still no color difference
formulas.
