wb: added DT_ILLUMINANT_FROM_WB, separated find_temperature_from_raw_coeffs into find_temperature_from_wb_coeffs, find_temperature_from_as_shot_coeffs; added handling to channelmixerrgb.c + altered logic for 'late correction' check

Author: kofa73

src/common/illuminants.h

@@ -34,6 +34,7 @@ typedef enum dt_illuminant_t
   DT_ILLUMINANT_BB              = 6, // $DESCRIPTION: "Planckian (black body)" general black body radiator - not CIE standard
   DT_ILLUMINANT_CUSTOM          = 7, // $DESCRIPTION: "custom" input x and y directly - bypass search
   DT_ILLUMINANT_CAMERA          = 10,// $DESCRIPTION: "as shot in camera" read RAW EXIF for WB
+  DT_ILLUMINANT_FROM_WB         = 11,// $DESCRIPTION: "as set in white balance module" read coefficients from the white balance module
   DT_ILLUMINANT_LAST,
   DT_ILLUMINANT_DETECT_SURFACES = 8,
   DT_ILLUMINANT_DETECT_EDGES    = 9,
@@ -215,19 +216,22 @@ static inline void illuminant_CCT_to_RGB(const float t, dt_aligned_pixel_t RGB)
   illuminant_xy_to_RGB(x, y, RGB);
 }
 
+static inline gboolean find_temperature_from_wb_coeffs(const dt_image_t *img, const dt_aligned_pixel_t wb_coeffs,
+                                            float *chroma_x, float *chroma_y);
 
 // Fetch image from pipeline and read EXIF for camera RAW WB coeffs
-static inline gboolean find_temperature_from_raw_coeffs(const dt_image_t *img, const dt_aligned_pixel_t custom_wb,
+static inline gboolean find_temperature_from_as_shot_coeffs(const dt_image_t *img, const dt_aligned_pixel_t correction_ratios,
                                                    float *chroma_x, float *chroma_y);
 
 
-static inline int illuminant_to_xy(const dt_illuminant_t illuminant, // primary type of illuminant
-                                   const dt_image_t *img,            // image container
-                                   const dt_aligned_pixel_t custom_wb, // optional user-set WB coeffs
-                                   float *x_out, float *y_out,       // chromaticity output
-                                   const float t,                    // temperature in K, if needed
-                                   const dt_illuminant_fluo_t fluo,  // sub-type of fluorescent illuminant, if needed
-                                   const dt_illuminant_led_t iled)   // sub-type of led illuminant, if needed
+static inline int illuminant_to_xy(const dt_illuminant_t illuminant,           // primary type of illuminant
+                                   const dt_image_t *img,                      // image container
+                                   const dt_aligned_pixel_t correction_ratios, // optional D65 correction ratios derived from user-set coefficients
+                                   const dt_aligned_pixel_t wb_coeffs,         // optional user-set WB coeffs (absolute)
+                                   float *x_out, float *y_out,                 // chromaticity output
+                                   const float t,                              // temperature in K, if needed
+                                   const dt_illuminant_fluo_t fluo,            // sub-type of fluorescent illuminant, if needed
+                                   const dt_illuminant_led_t iled)             // sub-type of led illuminant, if needed
 {
   /**
    * Compute the x and y chromaticity coordinates in Yxy spaces for standard illuminants
@@ -298,9 +302,15 @@ static inline int illuminant_to_xy(const dt_illuminant_t illuminant, // primary
     }
     case DT_ILLUMINANT_CAMERA:
     {
-      // Detect WB from RAW EXIF
+      // Detect WB from RAW EXIF, correcting with D65/wb_coeff ratios
       if(img)
-        if(find_temperature_from_raw_coeffs(img, custom_wb, &x, &y)) break;
+        if(find_temperature_from_as_shot_coeffs(img, correction_ratios, &x, &y)) break;
+    }
+    case DT_ILLUMINANT_FROM_WB:
+    {
+      // Detect WB from user-provided coefficients
+      if(img)
+        if(find_temperature_from_wb_coeffs(img, wb_coeffs, &x, &y)) break;
     }
     case DT_ILLUMINANT_CUSTOM: // leave x and y as-is
     case DT_ILLUMINANT_DETECT_EDGES:
@@ -385,31 +395,11 @@ static inline void matrice_pseudoinverse(float (*in)[3], float (*out)[3], int si
     }
 }
 
-
-static gboolean find_temperature_from_raw_coeffs(const dt_image_t *img, const dt_aligned_pixel_t custom_wb,
-                                            float *chroma_x, float *chroma_y)
+// returns TRUE is OK, FALSE if failed
+static gboolean get_CAM_to_XYZ(const dt_image_t * img, float(* CAM_to_XYZ)[3])
 {
-  if(img == NULL) return FALSE;
-  if(!dt_image_is_matrix_correction_supported(img)) return FALSE;
-
-  gboolean has_valid_coeffs = TRUE;
-  const int num_coeffs = (img->flags & DT_IMAGE_4BAYER) ? 4 : 3;
-
-  // Check coeffs
-  for(int k = 0; has_valid_coeffs && k < num_coeffs; k++)
-    if(!dt_isnormal(img->wb_coeffs[k]) || img->wb_coeffs[k] == 0.0f) has_valid_coeffs = FALSE;
-
-  if(!has_valid_coeffs) return FALSE;
-
-  // Get white balance camera factors
-  dt_aligned_pixel_t WB = { img->wb_coeffs[0], img->wb_coeffs[1], img->wb_coeffs[2], img->wb_coeffs[3] };
-
-  // Adapt the camera coeffs with custom white balance if provided
-  // this can deal with WB coeffs that don't use the input matrix reference
-  if(custom_wb)
-    for(size_t k = 0; k < 4; k++) WB[k] *= custom_wb[k];
-
-  // Get the camera input profile (matrice of primaries)
+  if(img == NULL || CAM_to_XYZ == NULL) return FALSE;
+  // Get the camera input profile (matrice of primaries) - embedded or raw library DB
   float XYZ_to_CAM[4][3];
   dt_mark_colormatrix_invalid(&XYZ_to_CAM[0][0]);
 
@@ -438,21 +428,61 @@ static gboolean find_temperature_from_raw_coeffs(const dt_image_t *img, const dt
 
   if(!dt_is_valid_colormatrix(XYZ_to_CAM[0][0])) return FALSE;
 
-  // Bloody input matrices define XYZ -> CAM transform, as if we often needed camera profiles to output
-  // So we need to invert them. Here go your CPU cycles again.
-  float CAM_to_XYZ[4][3];
   dt_mark_colormatrix_invalid(&CAM_to_XYZ[0][0]);
   matrice_pseudoinverse(XYZ_to_CAM, CAM_to_XYZ, 3);
-  if(!dt_is_valid_colormatrix(CAM_to_XYZ[0][0])) return FALSE;
+  return dt_is_valid_colormatrix(CAM_to_XYZ[0][0]);
+}
+
+// returns FALSE if failed; TRUE if successful
+static gboolean find_temperature_from_wb_coeffs(const dt_image_t *img, const dt_aligned_pixel_t wb_coeffs,
+                                            float *chroma_x, float *chroma_y)
+{
+  if(img == NULL || wb_coeffs == NULL) return FALSE;
+  if(!dt_image_is_matrix_correction_supported(img)) return FALSE;
+
+  float CAM_to_XYZ[4][3];
+  if(!get_CAM_to_XYZ(img, CAM_to_XYZ)) {
+    return FALSE;
+  }
 
   float x, y;
-  WB_coeffs_to_illuminant_xy(CAM_to_XYZ, WB, &x, &y);
+  WB_coeffs_to_illuminant_xy(CAM_to_XYZ, wb_coeffs, &x, &y);
   *chroma_x = x;
   *chroma_y = y;
 
   return TRUE;
 }
 
+// returns FALSE if failed; TRUE if successful
+static gboolean find_temperature_from_as_shot_coeffs(const dt_image_t *img, const dt_aligned_pixel_t correction_ratios,
+                                            float *chroma_x, float *chroma_y)
+{
+  if(img == NULL) return FALSE;
+
+  gboolean has_valid_coeffs = TRUE;
+  const int num_coeffs = (img->flags & DT_IMAGE_4BAYER) ? 4 : 3;
+
+  // Check coeffs
+  for(int k = 0; has_valid_coeffs && k < num_coeffs; k++)
+    if(!dt_isnormal(img->wb_coeffs[k]) || img->wb_coeffs[k] == 0.0f) has_valid_coeffs = FALSE;
+
+  if(!has_valid_coeffs) return FALSE;
+
+  // Get as-shot white balance camera factors (from raw)
+  // component wise raw-RGB * wb_coeffs should provide R=G=B for a neutral patch under
+  // the scene illuminant
+  dt_aligned_pixel_t WB = { img->wb_coeffs[0], img->wb_coeffs[1], img->wb_coeffs[2], img->wb_coeffs[3] };
+
+  // Adapt the camera coeffs with custom D65 coefficients if provided ('caveats' workaround)
+  // this can deal with WB coeffs that don't use the input matrix reference
+  // adaptation_ratios[k] = chr->D65coeffs[k] / chr->wb_coeffs[k]
+  if(correction_ratios)
+    for(size_t k = 0; k < 4; k++) WB[k] *= correction_ratios[k];
+  // for a neutral surface, raw RGB * img->wb_coeffs would produce neutral R=G=B
+
+  return find_temperature_from_wb_coeffs(img, WB, chroma_x, chroma_y);
+}
+
 
 DT_OMP_DECLARE_SIMD()
 static inline float planckian_normal(const float x, const float t)

src/develop/develop.h

@@ -147,9 +147,9 @@ typedef struct dt_dev_viewport_t
       - the currently used wb_coeffs in temperature module
       - D65coeffs and as_shot are read from exif data
   f)  - late_correction set by temperature if we want to process data as following
-      If we use the new DT_IOP_TEMP_D65_LATE mode in temperature.c and don#t have
-      any temp parameters changes later we can calc correction coeffs to modify
-      as_shot rgb data to D65
+      If we use the new DT_IOP_TEMP_D65_LATE mode or enable this in user modes of temperature.c
+      and don't have any temp parameters changes later we can calc correction ratios
+      to take white-balanced (neutralized) data to D65
 */
 typedef struct dt_dev_chroma_t
 {