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digitalmars.D - [OT] a good color distance function

reply Justin Johansson <no spam.com> writes:
Can anyone please suggest a decent algorithm for
determining a "color distance" metric between
two colors?  The requirement is to come up with
a good algorithm for contrasting a computed color
from another color.

Should this algorithm (function) be dependent upon
whether the color model be additive (aka RGB) or
subtractive (aka CMYK) or other?

Also should a decent "color distance" function take
in to account the possibility of color blindness
disability amongst the potential audience?

Somehow me thinks that (in say an RGB model) a
Pythagorean square-root of the the sum of the squares
of the respective RGB axis deltas is, whilst
mathematically pleasing, not best practice for
contemporary ideals/political correctness for addressing
accessibility/visual impairment issues.

Thanks in advance for your input,

Justin Johansson
Oct 14 2010
next sibling parent reply BCS <none anon.com> writes:
Hello Justin,


 Can anyone please suggest a decent algorithm for
 determining a "color distance" metric between
 two colors?  The requirement is to come up with
 a good algorithm for contrasting a computed color
 from another color.



I'd work in HSV. convert the hue channel to an absolute difference and then 
combine with a weighted sum. You might also take a look at some graphics 
design ideas about the color wheel (e.g. make the f(H) have peeks for
complementary 
colors) and you could have some fun with a crowd sourced fitness function 
driving a GA to get the tuning factors right.

-- 
... <IXOYE><
Oct 14 2010
parent Justin Johansson <no spam.com> writes:
On 15/10/2010 1:16 AM, BCS wrote:

 Hello Justin,

 I'd work in HSV. convert the hue channel to an absolute difference and
 then combine with a weighted sum. You might also take a look at some
 graphics design ideas about the color wheel (e.g. make the f(H) have
 peeks for complementary colors) and you could have some fun with a crowd
 sourced fitness function driving a GA to get the tuning factors right.



Thanks BCS for these useful ideas.
Cheers, Justin
Oct 15 2010
prev sibling next sibling parent reply ponce <spam spam.org> writes:
 
 Somehow me thinks that (in say an RGB model) a
 Pythagorean square-root of the the sum of the squares
 of the respective RGB axis deltas is, whilst
 mathematically pleasing, not best practice for
 contemporary ideals/political correctness for addressing
 accessibility/visual impairment issues.
 



Google for "daltonization"
Oct 14 2010
parent Justin Johansson <no spam.com> writes:
On 15/10/2010 2:54 AM, ponce wrote:

 Somehow me thinks that (in say an RGB model) a
 Pythagorean square-root of the the sum of the squares
 of the respective RGB axis deltas is, whilst
 mathematically pleasing, not best practice for
 contemporary ideals/political correctness for addressing
 accessibility/visual impairment issues.



 Google for "daltonization"



Another useful tip.  Thanks also ponce.
Cheers, Justin
Oct 15 2010
prev sibling parent =?UTF-8?B?IkrDqXLDtG1lIE0uIEJlcmdlciI=?= <jeberger free.fr> writes:
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

Justin Johansson wrote:

 Can anyone please suggest a decent algorithm for
 determining a "color distance" metric between
 two colors?  The requirement is to come up with
 a good algorithm for contrasting a computed color
 from another color.
=20
 Should this algorithm (function) be dependent upon
 whether the color model be additive (aka RGB) or
 subtractive (aka CMYK) or other?
=20



usually use the L*a*b* [1] or L*u*v* [2] color spaces. Pythagorean
distances in these spaces give reasonably good results, but more
advanced measures have been developed [3] if you need more precision.

		Jerome

[1] http://en.wikipedia.org/wiki/Lab_color_space
[2] http://en.wikipedia.org/wiki/CIELUV_color_space
[3] http://en.wikipedia.org/wiki/Color_difference
--=20
mailto:jeberger free.fr
http://jeberger.free.fr
Jabber: jeberger jabber.fr
Oct 16 2010