CIE: Make the XYZ to LAB code look similar to the RGB to LAB code

Such superficial differences make the code harder to scan when looking
for bugs and optimization opportunities.

diff --git a/extensions/CIE.c b/extensions/CIE.c
index b6fa513c391ef769a7198b6d07c8ae2be0497413..cb70d0f023398a6c7a43590e2b27c40597b975f3 100644 (file)
--- a/extensions/CIE.c
+++ b/extensions/CIE.c
@@ -172,24 +172,17 @@ XYZ_to_LAB (double X,
             double *to_a,
             double *to_b)
 {
-  double f_x, f_y, f_z;
+  double xr = X / D50_WHITE_REF_X;
+  double yr = Y / D50_WHITE_REF_Y;
+  double zr = Z / D50_WHITE_REF_Z;
 
-  double x_r = X / D50_WHITE_REF_X;
-  double y_r = Y / D50_WHITE_REF_Y;
-  double z_r = Z / D50_WHITE_REF_Z;
+  double fx = xr > LAB_EPSILON ? cbrt (xr) : (LAB_KAPPA * xr + 16.0) / 116.0;
+  double fy = yr > LAB_EPSILON ? cbrt (yr) : (LAB_KAPPA * yr + 16.0) / 116.0;
+  double fz = zr > LAB_EPSILON ? cbrt (zr) : (LAB_KAPPA * zr + 16.0) / 116.0;
 
-  if (x_r > LAB_EPSILON) f_x = cbrt(x_r);
-  else ( f_x = ((LAB_KAPPA * x_r) + 16) / 116.0 );
-
-  if (y_r > LAB_EPSILON) f_y = cbrt(y_r);
-  else ( f_y = ((LAB_KAPPA * y_r) + 16) / 116.0 );
-
-  if (z_r > LAB_EPSILON) f_z = cbrt(z_r);
-  else ( f_z = ((LAB_KAPPA * z_r) + 16) / 116.0 );
-
-  *to_L = (116.0 * f_y) - 16.0;
-  *to_a = 500.0 * (f_x - f_y);
-  *to_b = 200.0 * (f_y - f_z);
+  *to_L = 116.0 * fy - 16.0;
+  *to_a = 500.0 * (fx - fy);
+  *to_b = 200.0 * (fy - fz);
 }
 
 static inline void
@@ -200,26 +193,18 @@ LAB_to_XYZ (double L,
             double *to_Y,
             double *to_Z)
 {
-  double fy, fx, fz, fx_cubed, fy_cubed, fz_cubed;
-  double xr, yr, zr;
-
-  fy = (L + 16.0) / 116.0;
-  fy_cubed = fy*fy*fy;
-
-  fz = fy - (b / 200.0);
-  fz_cubed = fz*fz*fz;
-
-  fx = (a / 500.0) + fy;
-  fx_cubed = fx*fx*fx;
+  double fy = (L + 16.0) / 116.0;
+  double fy_cubed = fy * fy * fy;
 
-  if (fx_cubed > LAB_EPSILON) xr = fx_cubed;
-  else xr = ((116.0 * fx) - 16) / LAB_KAPPA;
+  double fx = fy + a / 500.0;
+  double fx_cubed = fx * fx * fx;
 
-  if ( L > (LAB_KAPPA * LAB_EPSILON) ) yr = fy_cubed;
-  else yr = (L / LAB_KAPPA);
+  double fz = fy - b / 200.0;
+  double fz_cubed = fz * fz * fz;
 
-  if (fz_cubed > LAB_EPSILON) zr = fz_cubed;
-  else zr = ( (116.0 * fz) - 16 ) / LAB_KAPPA;
+  double yr = L > LAB_KAPPA * LAB_EPSILON ? fy_cubed : L / LAB_KAPPA;
+  double xr = fx_cubed > LAB_EPSILON ? fx_cubed : (fx * 116.0 - 16.0) / LAB_KAPPA;
+  double zr = fz_cubed > LAB_EPSILON ? fz_cubed : (fz * 116.0 - 16.0) / LAB_KAPPA;
 
   *to_X = xr * D50_WHITE_REF_X;
   *to_Y = yr * D50_WHITE_REF_Y;