- refactored

2022-06-30 13:32:40 +02:00
parent 77cd5261b1
commit 776932e5d1
144 changed files with 0 additions and 38 deletions
@@ -0,0 +1,45 @@
+% function [xyz] = cielab2xyz(lab, ref_xyz)
+%
+% // C-Code
+% var_Y = ( CIE-L* + 16 ) / 116
+% var_X = CIE-a* / 500 + var_Y
+% var_Z = var_Y - CIE-b* / 200
+%
+% if ( var_Y^3 > 0.008856 ) var_Y = var_Y^3
+% else                      var_Y = ( var_Y - 16 / 116 ) / 7.787
+% if ( var_X^3 > 0.008856 ) var_X = var_X^3
+% else                      var_X = ( var_X - 16 / 116 ) / 7.787
+% if ( var_Z^3 > 0.008856 ) var_Z = var_Z^3
+% else                      var_Z = ( var_Z - 16 / 116 ) / 7.787
+% 
+% X = ref_X * var_X     //ref_X =  95.047  Observer= 2°, Illuminant= D65
+% Y = ref_Y * var_Y     //ref_Y = 100.000
+% Z = ref_Z * var_Z     //ref_Z = 108.883
+%
+% Source http://www.easyrgb.com
+
+function [xyz] = cielab2xyz(lab, ref_xyz)
+
+[m,n] = size(lab);
+if ((m ~= 3) & (n == 3))
+    lab = lab'
+end;
+
+xyz_k(2,:) = (lab(1,:) + 16)/116;
+xyz_k(1,:) = lab(2,:)/500 + xyz_k(2,:);
+xyz_k(3,:) = xyz_k(2,:) - lab(3,:)/200;
+
+xyz = f1(xyz_k);
+
+xyz(1,:) = xyz(1,:).*ref_xyz(1,:);
+xyz(2,:) = xyz(2,:).*ref_xyz(2,:);
+xyz(3,:) = xyz(3,:).*ref_xyz(3,:);
+
+function xyz = f1(xyz_k)
+thresh_n = 0.008856;
+
+[idx_m, idx_n] = find(xyz_k.^3 > thresh_n);
+xyz(idx_m,idx_n) = xyz_k(idx_m,idx_n).^3;
+
+[idx_m, idx_n] = find(xyz_k.^3 <= thresh_n);
+xyz(idx_m,idx_n) = (xyz_k(idx_m,idx_n) - 16/116)/7.787;