[imageio] [DAM] Support Exif flash tag value in addition to its exiv2 textual explanation

src/common/database.c

@@ -53,8 +53,9 @@
 // is created by running the upgrade steps.
 #define LAST_FULL_DATABASE_VERSION_LIBRARY 55
 #define LAST_FULL_DATABASE_VERSION_DATA    10
+
 // You HAVE TO bump THESE versions whenever you add an update branches to _upgrade_*_schema_step()!
-#define CURRENT_DATABASE_VERSION_LIBRARY 56
+#define CURRENT_DATABASE_VERSION_LIBRARY 57
 #define CURRENT_DATABASE_VERSION_DATA    13
 
 #define USE_NESTED_TRANSACTIONS
@@ -2948,6 +2949,15 @@ static int _upgrade_library_schema_step(dt_database_t *db, int version)
     sqlite3_exec(db->handle, "PRAGMA foreign_keys = ON", NULL, NULL, NULL);
     new_version = 56;
   }
+  else if(version == 56)
+  {
+    // The default value of -1 means that we have no information
+    // (the corresponding Exif tag has been removed or Exif has been
+    // removed altogether or the image format does not support Exif)
+    TRY_EXEC("ALTER TABLE main.images ADD COLUMN flash_tagvalue INTEGER DEFAULT -1",
+             "[init] can't add `flash_tagvalue' column to images table in database\n");
+    new_version = 57;
+  }
   else
     new_version = version; // should be the fallback so that calling code sees that we are in an infinite loop
 

src/common/exif.cc

@@ -1,6 +1,6 @@
 /*
    This file is part of darktable,
-   Copyright (C) 2009-2024 darktable developers.
+   Copyright (C) 2009-2025 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
@@ -1744,6 +1744,7 @@ static bool _exif_decode_exif_data(dt_image_t *img, Exiv2::ExifData &exifData)
     if(FIND_EXIF_TAG("Exif.Photo.Flash"))
     {
       const int value = pos->toLong();
+      img->exif_flash_tagvalue = value;
       if(value != 0)
       {
         _strlcpy_to_utf8(img->exif_flash, sizeof(img->exif_flash), pos, exifData);

src/common/image.c

@@ -1,6 +1,6 @@
 /*
   This file is part of darktable,
-  Copyright (C) 2009-2024 darktable developers.
+  Copyright (C) 2009-2025 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
@@ -1276,15 +1276,15 @@ static dt_imgid_t _image_duplicate_with_version_ext(const dt_imgid_t imgid,
      "   orientation, longitude, latitude, altitude, color_matrix,"
      "   colorspace, version, max_version,"
      "   history_end, position, aspect_ratio, exposure_bias, import_timestamp,"
-     "   whitebalance_id, flash_id, exposure_program_id, metering_mode_id)"
+     "   whitebalance_id, flash_id, exposure_program_id, metering_mode_id, flash_tagvalue)"
      " SELECT NULL, group_id, film_id, width, height, filename,"
      "        maker_id, model_id, camera_id, lens_id,"
      "        exposure, aperture, iso, focal_length, focus_distance, datetime_taken,"
      "        flags, output_width, output_height, crop, raw_parameters,"
      "        raw_black, raw_maximum, orientation,"
      "        longitude, latitude, altitude, color_matrix, colorspace, NULL, NULL, 0, ?1,"
      "        aspect_ratio, exposure_bias, import_timestamp,"
-     "        whitebalance_id, flash_id, exposure_program_id, metering_mode_id"
+     "        whitebalance_id, flash_id, exposure_program_id, metering_mode_id, flash_tagvalue"
      " FROM main.images WHERE id = ?2",
      -1, &stmt, NULL);
   // clang-format on
@@ -2106,6 +2106,7 @@ void dt_image_init(dt_image_t *img)
   memset(img->camera_makermodel, 0, sizeof(img->camera_makermodel));
   memset(img->filename, 0, sizeof(img->filename));
   g_strlcpy(img->filename, "(unknown)", sizeof(img->filename));
+  img->exif_flash_tagvalue = -1; // -1 means we have no data (this is not the same as "flash not fired")
   img->exif_crop = 1.0;
   img->exif_exposure = 0;
   img->exif_exposure_bias = DT_EXIF_TAG_UNINITIALIZED;
@@ -2458,15 +2459,15 @@ dt_imgid_t dt_image_copy_rename(const dt_imgid_t imgid,
          "   raw_black, raw_maximum, orientation,"
          "   longitude, latitude, altitude, color_matrix, colorspace, version, max_version,"
          "   position, aspect_ratio, exposure_bias,"
-         "   whitebalance_id, flash_id, exposure_program_id, metering_mode_id)"
+         "   whitebalance_id, flash_id, exposure_program_id, metering_mode_id, flash_tagvalue)"
          " SELECT NULL, group_id, ?1 as film_id, width, height, ?2 as filename,"
          "        maker_id, model_id, lens_id,"
          "        exposure, aperture, iso, focal_length, focus_distance, datetime_taken,"
          "        flags, width, height, crop, raw_parameters, raw_black, raw_maximum,"
          "        orientation, longitude, latitude, altitude,"
          "        color_matrix, colorspace, -1, -1,"
          "        ?3, aspect_ratio, exposure_bias,"
-         "        whitebalance_id, flash_id, exposure_program_id, metering_mode_id"
+         "        whitebalance_id, flash_id, exposure_program_id, metering_mode_id, flash_tagvalue"
          " FROM main.images"
          " WHERE id = ?4",
         -1, &stmt, NULL);

src/common/image.h

@@ -268,6 +268,7 @@ typedef struct dt_image_t
   float exif_focal_length;
   float exif_focus_distance;
   float exif_crop;
+  int32_t exif_flash_tagvalue;
   char exif_maker[64];
   char exif_model[64];
   char exif_lens[128];

src/common/image_cache.c

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2009-2024 darktable developers.
+    Copyright (C) 2009-2025 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
@@ -49,7 +49,7 @@ static void _image_cache_allocate(void *data,
       "       raw_black, raw_maximum, aspect_ratio, exposure_bias,"
       "       import_timestamp, change_timestamp, export_timestamp, print_timestamp,"
       "       output_width, output_height, cm.maker, cm.model, cm.alias,"
-      "       wb.name, fl.name, ep.name, mm.name"
+      "       wb.name, fl.name, ep.name, mm.name, flash_tagvalue"
       "  FROM main.images AS mi"
       "       LEFT JOIN main.cameras AS cm ON cm.id = mi.camera_id"
       "       LEFT JOIN main.makers AS mk ON mk.id = mi.maker_id"
@@ -154,6 +154,8 @@ static void _image_cache_allocate(void *data,
     str = (char *)sqlite3_column_text(stmt, 41);
     if(str) g_strlcpy(img->exif_metering_mode, str, sizeof(img->exif_metering_mode));
 
+    img->exif_flash_tagvalue = sqlite3_column_int(stmt, 42);
+
     dt_color_harmony_get(entry->key, &img->color_harmony_guide);
 
     // buffer size? colorspace?
@@ -343,7 +345,7 @@ void dt_image_cache_write_release_info(dt_image_t *img,
      "     import_timestamp = ?28, change_timestamp = ?29, export_timestamp = ?30,"
      "     print_timestamp = ?31, output_width = ?32, output_height = ?33,"
      "     whitebalance_id = ?36, flash_id = ?37,"
-     "     exposure_program_id = ?38, metering_mode_id = ?39"
+     "     exposure_program_id = ?38, metering_mode_id = ?39, flash_tagvalue = ?41"
      " WHERE id = ?40",
      -1, &stmt, NULL);
 
@@ -409,6 +411,7 @@ void dt_image_cache_write_release_info(dt_image_t *img,
   DT_DEBUG_SQLITE3_BIND_INT(stmt, 38, exposure_program_id);
   DT_DEBUG_SQLITE3_BIND_INT(stmt, 39, metering_mode_id);
   DT_DEBUG_SQLITE3_BIND_INT(stmt, 40, img->id);
+  DT_DEBUG_SQLITE3_BIND_INT(stmt, 41, img->exif_flash_tagvalue);
 
   const int rc = sqlite3_step(stmt);
   if(rc != SQLITE_DONE)

src/common/variables.c

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2010-2024 darktable developers.
+    Copyright (C) 2010-2025 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
@@ -106,17 +106,6 @@ typedef struct dt_variables_data_t
 
 static char *_expand_source(dt_variables_params_t *params, char **source, char extra_stop);
 
-static gboolean _is_flash_fired(const dt_image_t *img)
-{
-  if(img->exif_flash[0] == '\0') // string is empty
-    return FALSE;                // so we can't claim that flash fired
-  if(g_strrstr(img->exif_flash, "did not fire"))
-    return FALSE;
-  if(img->exif_flash[0] == 'N')  // "No", that is no flash function present
-    return FALSE;
-  else
-    return TRUE;  // all other strings mean that the flash fired
-}
 
 // gather some data that might be used for variable expansion
 static void _init_expansion(dt_variables_params_t *params, gboolean iterate)
@@ -192,8 +181,22 @@ static void _init_expansion(dt_variables_params_t *params, gboolean iterate)
     params->data->longitude = img->geoloc.longitude;
     params->data->latitude = img->geoloc.latitude;
     params->data->elevation = img->geoloc.elevation;
-    params->data->exif_flash_icon = _is_flash_fired(img) ? "⚡" : "";
-    params->data->exif_flash = _is_flash_fired(img) ? _("yes") : _("no");
+
+
+    // We don't want to claim that the flash did not fire when the photo is
+    // clearly taken with a flash, but information about this is not available
+    if(img->exif_flash_tagvalue == -1)
+    {
+       params->data->exif_flash_icon = "";
+       params->data->exif_flash = _("no info");
+    }
+    else
+    {
+      // Bit 0 set means that flash was fired
+      params->data->exif_flash_icon = (img->exif_flash_tagvalue & 1) ? "⚡" : "";
+      params->data->exif_flash = (img->exif_flash_tagvalue & 1) ? _("yes") : _("no");
+    }
+
     params->data->exif_exposure_program = img->exif_exposure_program;
     params->data->exif_metering_mode = img->exif_metering_mode;
     params->data->exif_whitebalance = img->exif_whitebalance;