Revamp D65 chroma correction workflow

src/develop/develop.c

@@ -128,10 +128,8 @@ void dt_dev_init(dt_develop_t *dev,
   dev->iop_order_list = NULL;
 
   dev->proxy.exposure.module = NULL;
-  dev->proxy.chroma_adaptation = NULL;
-  dev->proxy.wb_is_D65 = TRUE; // don't display error messages until
-                               // we know for sure it's FALSE
-  dev->proxy.wb_coeffs[0] = 0.f;
+
+  dt_dev_init_chroma(dev);
 
   dev->rawoverexposed.enabled = FALSE;
   dev->rawoverexposed.mode =
@@ -162,8 +160,8 @@ void dt_dev_cleanup(dt_develop_t *dev)
   dt_pthread_mutex_destroy(&dev->full.pipe_mutex);
   dt_pthread_mutex_destroy(&dev->preview_pipe_mutex);
   dt_pthread_mutex_destroy(&dev->preview2.pipe_mutex);
-  dev->proxy.chroma_adaptation = NULL;
-  dev->proxy.wb_coeffs[0] = 0.f;
+  dt_dev_init_chroma(dev);
+
   if(dev->full.pipe)
   {
     dt_dev_pixelpipe_cleanup(dev->full.pipe);
@@ -3805,7 +3803,6 @@ void dt_dev_image(const dt_imgid_t imgid,
                   size_t *processed_height)
 {
   // create a dev
-
   dt_dev_image_ext(imgid, width, height,
                    history_end,
                    buf, processed_width, processed_height,
@@ -3814,6 +3811,44 @@ void dt_dev_image(const dt_imgid_t imgid,
                    darktable.develop->iso_12646.enabled, -1);
 }
 
+gboolean dt_dev_equal_chroma(const float *f, const double *d)
+{
+  return feqf(f[0], (float)d[0], 0.00001)
+      && feqf(f[1], (float)d[1], 0.00001)
+      && feqf(f[2], (float)d[2], 0.00001);
+}
+
+gboolean dt_dev_D65_chroma(const dt_develop_t *dev)
+{
+  const dt_dev_chroma_t *chr = &dev->chroma;
+  const float wb_coeffs[4] = {chr->wb_coeffs[0], chr->wb_coeffs[1], chr->wb_coeffs[2], chr->wb_coeffs[3] };
+  return chr->late_correction ? dt_dev_equal_chroma(wb_coeffs, chr->as_shot)
+                              : dt_dev_equal_chroma(wb_coeffs, chr->D65coeffs);
+}
+
+void dt_dev_reset_chroma(dt_develop_t *dev)
+{
+  dt_dev_chroma_t *chr = &dev->chroma;
+  chr->adaptation = NULL;
+  chr->late_correction = FALSE;
+  for_four_channels(c)
+    chr->wb_coeffs[c] = 1.0;
+}
+
+void dt_dev_init_chroma(dt_develop_t *dev)
+{
+  dt_dev_chroma_t *chr = &dev->chroma;
+  chr->adaptation = NULL;
+  chr->temperature = NULL;
+  chr->late_correction = FALSE;
+  for_four_channels(c)
+  {
+    chr->wb_coeffs[c] = 1.0;
+    chr->D65coeffs[c] = 1.0;
+    chr->as_shot[c] = 1.0;
+  }
+}
+
 // clang-format off
 // modelines: These editor modelines have been set for all relevant files by tools/update_modelines.py
 // vim: shiftwidth=2 expandtab tabstop=2 cindent

src/develop/develop.h

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2009-2021 darktable developers.
+    Copyright (C) 2009-2023 darktable developers.
 
     darktable is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -144,6 +144,32 @@ typedef struct dt_dev_viewport_t
   gboolean input_changed;
 } dt_dev_viewport_t;
 
+/* keep track on what and where we do chromatic adaptation, used
+  a)  to display warnings in GUI of modules that should probably not be doing
+      white balance
+  b)  missing required white balance
+  c)  allow late correction of as-shot or modified coeffs to D65 in color-input
+      but keep processing until then with more reliable (at least for highlights,
+      raw chromatic aberrations and more.
+  d)  avoids keeping of fixed data in temperature gui data
+  e)  we have 3 coefficients kept here
+      - 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
+*/
+typedef struct dt_dev_chroma_t
+{
+  struct dt_iop_module_t *temperature;  // always available for GUI reports
+  struct dt_iop_module_t *adaptation;   // set if one module is processing this without blending
+
+  double wb_coeffs[4];                  // data actually used by the pipe
+  double D65coeffs[4];                  // both read from exif data or "best guess"
+  double as_shot[4];
+  gboolean late_correction;
+} dt_dev_chroma_t;
 
 typedef struct dt_develop_t
 {
@@ -273,19 +299,10 @@ typedef struct dt_develop_t
                                struct dt_iop_module_t *module,
                                const dt_mask_id_t selectid);
     } masks;
-
-    // what is the ID of the module currently doing pipeline chromatic
-    // adaptation ?  this is to prevent multiple modules/instances
-    // from doing white balance globally.  only used to display
-    // warnings in GUI of modules that should probably not be doing
-    // white balance
-    struct dt_iop_module_t *chroma_adaptation;
-
-    // is the WB module using D65 illuminant and not doing full chromatic adaptation ?
-    gboolean wb_is_D65;
-    dt_aligned_pixel_t wb_coeffs;
   } proxy;
 
+  dt_dev_chroma_t chroma;
+
   // for exposing the crop
   struct
   {
@@ -661,6 +678,12 @@ void dt_dev_image_ext(const dt_imgid_t imgid,
                       const gboolean iso_12646,
                       const int32_t snapshot_id);
 
+
+gboolean dt_dev_equal_chroma(const float *f, const double *d);
+gboolean dt_dev_D65_chroma(const dt_develop_t *dev);
+void dt_dev_reset_chroma(dt_develop_t *dev);
+void dt_dev_init_chroma(dt_develop_t *dev);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif /* __cplusplus */

src/develop/imageop.c

@@ -1114,8 +1114,8 @@ static void _gui_off_callback(GtkToggleButton *togglebutton, gpointer user_data)
       module->enabled = FALSE;
 
       //  if current module is set as the CAT instance, remove that setting
-      if(module->dev->proxy.chroma_adaptation == module)
-        module->dev->proxy.chroma_adaptation = NULL;
+      if(module->dev->chroma.adaptation == module)
+        module->dev->chroma.adaptation = NULL;
 
       dt_dev_add_history_item(module->dev, module, FALSE);