add rgb_{to,from}_linear, lsRGB space

PDLPorters · Jan 12, 2023 · ee606be · ee606be
1 parent 73e4f76
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Showing 4 changed files with 105 additions and 5 deletions.
diff --git a/Changes b/Changes
@@ -1,6 +1,7 @@
 - no need to supply mstar for add_rgb_space
 - can supply add_rgb_space-format hash-ref to the relevant functions
-- add rgb_to_lab and lab_to_rgb
+- add rgb_to_lab, lab_to_rgb, rgb_{to,from}_linear
+- add lsRGB colour space
 
 0.201 2022-02-14
 - more accurate dependencies

diff --git a/ColorSpace/RGBSpace.pm b/ColorSpace/RGBSpace.pm
@@ -241,6 +241,27 @@ our $RGB_SPACE = {
                              ]),
                       'white_point' => $WHITE_POINT->{'D65'},
                     },
+          'lsRGB' => {
+                      'gamma' => 1.0,
+                      'm' => pdl([
+                               [
+                                 '0.412423757575757',
+                                 '0.212656',
+                                 '0.0193323636363636'
+                               ],
+                               [
+                                 '0.357579',
+                                 '0.715158',
+                                 '0.119193'
+                               ],
+                               [
+                                 '0.180465',
+                                 '0.072186',
+                                 '0.950449'
+                               ]
+                             ]),
+                      'white_point' => $WHITE_POINT->{'D65'},
+                    },
           'ColorMatch' => {
                             'gamma' => '1.8',
                             'm' => pdl([

diff --git a/color_space.pd b/color_space.pd
@@ -125,6 +125,7 @@ Some conversions require specifying the RGB space which includes gamma curve and
     SMPTE-C [SMPTE]
     WideGamut
     sRGB [709] [CIE Rec 709]
+    lsRGB
 
 You can also add custom RGB space definitions via the function add_rgb_space.
 Alternatively, as of 0.202 you can directly supply the function with a
@@ -667,6 +668,73 @@ BADDOC
 );
 
 
+pp_def('rgb_to_linear',
+    Pars => 'rgb(c=3); gamma(); [o]out(c=3)',
+    HandleBad => 1,
+    GenericTypes=>['D'],
+    Code => '
+        PDL_IF_BAD(if ($ISBAD(rgb(c=>0)) || $ISBAD(rgb(c=>1)) || $ISBAD(rgb(c=>2))) {
+            loop (c) %{ $SETBAD(out()); %}
+        }
+        else,) {
+            rgb2linear( $P(rgb), $gamma(), $P(out) );
+        }
+    ',
+    Doc => <<'DOCUMENTATION',
+=for ref
+
+Converts an RGB color triple (presumably with gamma) to an RGB color triple
+with linear values.
+
+=for usage
+
+Usage:
+
+    my $rgb_linear = rgb_to_linear( $gammaed, 2.2 );
+DOCUMENTATION
+    BadDoc => <<BADDOC,
+=for bad
+
+If C<rgb_to_linear> encounters a bad value in any of the R, G, or B
+values the output ndarray will be marked as bad and the associated R,
+G, and B values will all be marked as bad.
+BADDOC
+);
+
+
+pp_def('rgb_from_linear',
+    Pars => 'rgb(c=3); gamma(); [o]out(c=3)',
+    HandleBad => 1,
+    GenericTypes=>['D'],
+    Code => '
+        PDL_IF_BAD(if ($ISBAD(rgb(c=>0)) || $ISBAD(rgb(c=>1)) || $ISBAD(rgb(c=>2))) {
+            loop (c) %{ $SETBAD(out()); %}
+        }
+        else,) {
+            rgb2gamma( $P(rgb), $gamma(), $P(out) );
+        }
+    ',
+    Doc => <<'DOCUMENTATION',
+=for ref
+
+Converts an RGB color triple (presumably linear) to an RGB color triple
+with the specified gamma.
+
+=for usage
+
+Usage:
+
+    my $gammaed = rgb_from_linear( $rgb_linear, 2.2 );
+DOCUMENTATION
+    BadDoc => <<BADDOC,
+=for bad
+
+If C<rgb_from_linear> encounters a bad value in any of the R, G, or B
+values the output ndarray will be marked as bad and the associated R,
+G, and B values will all be marked as bad.
+BADDOC
+);
+
 
 pp_addpm(<<'EOD');
 

diff --git a/t/color_space.t b/t/color_space.t
@@ -81,17 +81,27 @@ sub tapprox {
 	ok( tapprox( $a_rgb_bad, $rgb), 'hsv_to_rgb with bad value' ) or diag($a_rgb_bad, $rgb);
 }
 
-# rgb_to_xyz
+# rgb_to_xyz and rgb_{to,from}_linear
 {   
 	my $rgb = pdl( [255,255,255],[0,0,0],[255,10,50],[1,48,199] ) / 255;
 	my $xyz = pdl( [0.950467757575757, 1, 1.08897436363636],
-				   [0,0,0],
-				   [0.419265223936783, 0.217129144548417, 0.0500096992920757],
-				   [0.113762127389896, 0.0624295703768394, 0.546353858701224] );
+	  [0,0,0],
+	  [0.419265223936783, 0.217129144548417, 0.0500096992920757],
+	  [0.113762127389896, 0.0624295703768394, 0.546353858701224] );
+	my $linear_ans = pdl( [1,1,1],[0,0,0],
+	  [1, 0.0030352698, 0.031896033],
+	  [0.00030352698, 0.029556834, 0.57112483] );
 
 	my $a_xyz = rgb_to_xyz( $rgb, 'sRGB' );
 	ok( tapprox( $a_xyz, $xyz), 'rgb_to_xyz sRGB' ) or diag($a_xyz, $xyz);
 
+	my $rgb_linear = rgb_to_linear($rgb, -1);
+	ok( tapprox( $rgb_linear, $linear_ans), 'rgb_to_linear sRGB' ) or diag($rgb_linear, $linear_ans);
+	my $rgb_regamma = rgb_from_linear($rgb_linear, -1);
+	ok( tapprox( $rgb_regamma, $rgb), 're-rgb_from_linear sRGB' ) or diag($rgb_regamma, $rgb);
+	my $a2_xyz = rgb_to_xyz( $rgb_linear, 'lsRGB' );
+	ok( tapprox( $a2_xyz, $xyz), 'rgb_to_xyz lsRGB' ) or diag($a2_xyz, $xyz);
+
 	my $a_rgb = xyz_to_rgb( $xyz, 'sRGB' );
 	ok( tapprox( $a_rgb, $rgb), 'xyz_to_rgb sRGB' ) or diag($a_rgb, $rgb);