- refactored

2022-06-30 13:32:40 +02:00
parent 77cd5261b1
commit 776932e5d1
144 changed files with 0 additions and 38 deletions
@@ -0,0 +1,47 @@
+% function [lab] = xyz2cielab(xyz, ref_xyz)
+%
+% // C-Code
+% var_X = X /  95.047          //Observer = 2°, Illuminant = D65
+% var_Y = Y / 100.000
+% var_Z = Z / 108.883
+%
+% if ( var_X > 0.008856 ) var_X = var_X ^ ( 1/3 )
+% else                    var_X = ( 7.787 * var_X ) + ( 16 / 116 )
+% if ( var_Y > 0.008856 ) var_Y = var_Y ^ ( 1/3 )
+% else                    var_Y = ( 7.787 * var_Y ) + ( 16 / 116 )
+% if ( var_Z > 0.008856 ) var_Z = var_Z ^ ( 1/3 )
+% else                    var_Z = ( 7.787 * var_Z ) + ( 16 / 116 )
+%
+% CIE-L* = ( 116 * var_Y ) - 16
+% CIE-a* = 500 * ( var_X - var_Y )
+% CIE-b* = 200 * ( var_Y - var_Z )
+%
+% Source http://www.easyrgb.com
+
+function [lab] = xyz2cielab(xyz, ref_xyz)
+
+[m,n] = size(xyz);
+if ((m ~= 3) & (n == 3))
+    xyz = xyz'
+end;
+
+xyz(1,:) = xyz(1,:)./ref_xyz(1,:);
+xyz(2,:) = xyz(2,:)./ref_xyz(2,:);
+xyz(3,:) = xyz(3,:)./ref_xyz(3,:);
+xyz_k = f1(xyz);
+
+% L
+lab(1,:) = 116*xyz_k(2,:) - 16;
+% a
+lab(2,:) = 500*(xyz_k(1,:) - xyz_k(2,:));
+% b
+lab(3,:) = 200*(xyz_k(2,:) - xyz_k(3,:));
+
+function xyz_k = f1(xyz)
+thresh_n = 0.008856;
+
+[idx_m, idx_n] = find(xyz > thresh_n);
+xyz_k(idx_m,idx_n) = xyz(idx_m,idx_n).^(1/3);
+
+[idx_m, idx_n] = find(xyz <= thresh_n);
+xyz_k(idx_m,idx_n) = 7.787 * xyz(idx_m,idx_n) + 16/116;