OpenEuphoria

color difference equations

• Posted by Tone Škoda <tskoda at email.si> Sep 29, 2004
• 513 views

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