Re: difference between two colors
- Posted by rforno at tutopia.com
Jun 08, 2001
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I'd assume r, g, b are the axis of a 3-dimensional space, and so their =
possible values span a cube. Then I would compute the geometrical =
distance between the 2 points in such a space, but I am too lazy to =
write the function...
----- Original Message -----=20
From: Tone Skoda=20
To: EUforum=20
Sent: Thursday, June 07, 2001 7:20 AM
Subject: difference between two colors
Can anyone think of any better function to get difference between two =
colors.
-- Returns the difference between two colors.
-- It should return the biggest difference when colors are WHITE and =
BLACK.
-- Examples (all assume that 'color_importance' is 1):
-- If colors are black{0, 0, 0} and white {255, 255, 255} it returns:
-- 0 + 0 + 0 + brightness_importance * 255 * 3 =3D =
brightness_importance * 765.
-- If colors are red {255, 0, 0} and green {0, 255, 0} it returns:
-- 255 + 255 + 0 + brightness_importance * 0 =3D 255 + 255 =3D 510.
-- If colors are gray {127, 127, 127} and black {0, 0, 0} it returns:
-- 0 + 0 + 0 + brightness_importance * 127 * 3
-- =3D brightness_importance * 381.
-- (These examples don't assume that 'color_importance' is 1):
-- If colors are {127, 127, 127} and {127, 128, 127} it returns:
-- color_importance * (1 + 0 + 1) + brightness_importance * 1 =3D
-- =3D 2 * color_importance + brightness_importance.
-- So: the difference between two colors which have only one of the =
three color values
-- different for only one unit is 1, if 'brightness_importance' is 0.5 =
and
-- 'color_importance' is 0.25.
function reco_color_difference (atom color1, atom color2)
-- The bigger this number is the more important the brightness =
difference
-- between the two colors is.
atom brightness_importance
-- Color importance. Modify these two values if neccessary in the =
future. =20
atom color_importance
atom ret
integer red1, green1, blue1, red2, green2, blue2
color_importance =3D 0.25
brightness_importance =3D 0.5
red1 =3D GetRValue (color1)
green1 =3D GetGValue (color1)
blue1 =3D GetBValue (color1)
red2 =3D GetRValue (color2)
green2 =3D GetGValue (color2)
blue2 =3D GetBValue (color2)
ret =3D (
color_importance * (
-- red - green
abs (abs (red1 - green1) - abs (red2 - green2))
-- red - blue
+ abs (abs (red1 - blue1) - abs (red2 - blue2))
-- green - blue
+ abs (abs (green1 - blue1) - abs (green2 - blue2))
)
-- brightness difference
+ brightness_importance * abs ((red1 + green1 + blue1) - =
(red2 + green2 + blue2))
)
return ret
end function
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<DIV><FONT face=3DArial size=3D2>I'd assume r, g, b are the axis of a =
3-dimensional=20
space, and so their possible values span a cube. Then I would compute =
the=20
geometrical distance between the 2 points in such a space, but I am too =
lazy to=20
write the function...</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dtone.skoda at siol.net =
href=3D"mailto:tone.skoda at siol.net">Tone Skoda</A>=20
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3DEUforum at topica.com=20
href=3D"mailto:EUforum at topica.com">EUforum</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, June 07, 2001 =
7:20=20
AM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> difference between two =
colors</DIV>
<A =
colors.<BR>-- It should return the biggest difference when colors are =
WHITE=20
and BLACK.<BR>-- Examples (all assume that 'color_importance' is =
1):<BR>-- If=20
colors are black{0, 0, 0} and white {255, 255, 255} it=20
returns:<BR>-- 0 + 0 + 0 + brightness_importance * =
255 * 3 =3D=20
brightness_importance * 765.<BR>-- If colors are red {255, 0, 0} and =
green {0,=20
255, 0} it returns:<BR>-- 255 + 255 + 0 + =
brightness_importance *=20
0 =3D 255 + 255 =3D 510.<BR>-- If colors are gray {127, 127, 127} and =
black {0, 0,=20
0} it returns:<BR>-- 0 + 0 + 0 + brightness_importance * =
127 *=20
3<BR>-- =3D brightness_importance * 381.<BR>-- =
(These examples=20
don't assume that 'color_importance' is 1):<BR>-- If colors are {127, =
127,=20
127} and {127, 128, 127} it returns:<BR>-- color_importance * (1 + 0 + =
1) +=20
brightness_importance * 1 =3D<BR>-- =3D 2 * color_importance +=20
brightness_importance.<BR>-- So: the difference between two colors =
which have=20
only one of the three color values<BR>-- different for only one unit =
is 1, if=20
'brightness_importance' is 0.5 and<BR>-- 'color_importance' is=20
0.25.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><BR>function reco_color_difference =
(atom color1,=20
atom color2)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2> -- The bigger this =
number is=20
the more important the brightness difference<BR> -- =
between=20
the two colors is.<BR> atom=20
brightness_importance<BR> -- Color importance. =
Modify these=20
two values if neccessary in the future. =
<BR> =20
atom color_importance</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>
<DIV><FONT face=3DArial size=3D2> atom=20
ret</FONT><BR> integer red1, green1, blue1, red2, =
green2,=20
blue2</FONT></DIV></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2> color_importance =
=3D=20
0.25<BR> brightness_importance =3D =
0.5<BR> =20
red1 =3D GetRValue (color1)<BR> green1 =3D GetGValue =
(color1)<BR> blue1 =3D GetBValue=20
(color1)<BR> red2 =3D GetRValue =
(color2)<BR> =20
green2 =3D GetGValue (color2)<BR> blue2 =3D =
GetBValue=20
(color2)<BR> ret =3D=20
=
(<BR> =20
color_importance *=20
=
(<BR> &n=
bsp; =20
-- red -=20
=
green<BR> &nbs=
p; =20
abs (abs (red1 - green1) - abs (red2 -=20
=
green2))<BR> &=
nbsp; =20
-- red -=20
=
blue<BR>  =
; =20
+ abs (abs (red1 - blue1) - abs (red2 -=20
=
blue2))<BR> &n=
bsp; =20
-- green -=20
=
blue<BR>  =
; =20
+ abs (abs (green1 - blue1) - abs (green2 -=20
=
blue2))<BR> &n=
bsp;=20
=
)<BR> =
--=20
brightness=20
=
difference<BR>  =
; =20
+ brightness_importance * abs ((red1 + green1 + blue1) - (red2 + =
green2 +=20
blue2))<BR> =
)<BR> =20
return ret<BR>end =
function</FONT></DIV><PRE>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
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