1al_color_distance_ciede2000(3)                  al_color_distance_ciede2000(3)
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NAME

6       al_color_distance_ciede2000 - Allegro 5 API
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SYNOPSIS

9              #include <allegro5/allegro_color.h>
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11              double al_color_distance_ciede2000(ALLEGRO_COLOR color1,
12                    ALLEGRO_COLOR color2) {
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DESCRIPTION

15       This  function  computes the CIEDE2000 color difference between two RGB
16       colors.  This is a visually uniform color difference, unlike for  exam‐
17       ple the RGB distance.
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19       When  using  the RGB distance (Euklidean distance between two RGB trip‐
20       lets) there can be color pairs with the same distance, where the colors
21       of one pair appear to be almost the same color, while the colors of the
22       other pair look quite different.  This is improved by using the  L*a*b*
23       color  space  which  was  designed  with perceptual uniformity in mind.
24       However it still is not completely uniform.  The CIEDE2000 formula con‐
25       tains some additional transformations to fix that.
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27       The returned color distance is roughly in the range 0 (identical color)
28       to 1 (completely different color) - but values  greater  than  one  are
29       possible.
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31              Note:  This  function  uses al_color_lab(3) internally which de‐
32              fines the L component to be in the range 0..1 (and not 0..100 as
33              is sometimes seen).
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SINCE

36       5.2.3
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40Allegro reference manual                        al_color_distance_ciede2000(3)