Add color fit criteria for Color Mode conversion (fix #2787, #4416)

Added other color comparison criterias (fit criteria) during
color mode conversion RGBA to Indexed or Grayscale to Indexed.
The 'fit criteria' will help us to recolor an RGB image with
a limited color palette taking into account different color
perception criteria (color spaces: RGB, linearized RGB,
CIE XYZ, CIE LAB).

src/app/cmd/set_pixel_format.cpp

@@ -130,7 +130,8 @@ SetPixelFormat::SetPixelFormat(Sprite* sprite,
                        false, // TODO is background? it depends of the layer where this tileset is used
                        mapAlgorithm,
                        toGray,
-                       &superDel);
+                       &superDel,
+                       fitCriteria);
         }
         superDel.nextImage();
       }

src/app/cmd/set_pixel_format.h

@@ -39,7 +39,7 @@ namespace cmd {
                    const doc::RgbMapAlgorithm mapAlgorithm,
                    doc::rgba_to_graya_func toGray,
                    render::TaskDelegate* delegate,
-                   const doc::FitCriteria fitCriteria = doc::FitCriteria::DEFAULT);
+                   const doc::FitCriteria fitCriteria);
 
   protected:
     void onExecute() override;

src/app/commands/cmd_change_pixel_format.cpp

@@ -668,9 +668,10 @@ void ChangePixelFormatCommand::onExecute(Context* context)
     window.saveOptions();
   }
   else {
-    // TO DO: in a first approach a simple conversion to indexed color mode
-    // it's just via the old fit criteria (Euclidean color distance).
-    m_fitCriteria = FitCriteria::DEFAULT;
+    if (m_format == IMAGE_INDEXED) {
+      m_rgbmap = Preferences::instance().quantization.rgbmapAlgorithm();
+      m_fitCriteria = Preferences::instance().quantization.fitCriteria();
+    }
   }
 
   // No conversion needed

src/app/commands/cmd_new_file.cpp

@@ -263,6 +263,11 @@ void NewFileCommand::onExecute(Context* ctx)
     else
       layer->setName(fmt::format("{} {}", Strings::commands_NewLayer_Layer(), 1));
   }
+  if (sprite->pixelFormat() == IMAGE_INDEXED) {
+    sprite->rgbMap(0, Sprite::RgbMapFor(!layer->isBackground()),
+                   Preferences::instance().quantization.rgbmapAlgorithm(),
+                   Preferences::instance().quantization.fitCriteria());
+  }
 
   // Show the sprite to the user
   std::unique_ptr<Doc> doc(new Doc(sprite.get()));

src/app/doc_exporter.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2023  Igara Studio S.A.
+// Copyright (C) 2018-2024  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -1289,13 +1289,18 @@ void DocExporter::renderTexture(Context* ctx,
     // Make the sprite compatible with the texture so the render()
     // works correctly.
     if (sample.sprite()->pixelFormat() != textureImage->pixelFormat()) {
+      RgbMapAlgorithm rgbmapAlgo =
+        Preferences::instance().quantization.rgbmapAlgorithm();
+      FitCriteria fc =
+        Preferences::instance().quantization.fitCriteria();
       cmd::SetPixelFormat(
         sample.sprite(),
         textureImage->pixelFormat(),
         render::Dithering(),
-        Sprite::DefaultRgbMapAlgorithm(), // TODO add rgbmap algorithm preference
+        rgbmapAlgo,
         nullptr, // toGray is not needed because the texture is Indexed or RGB
-        nullptr) // TODO add a delegate to show progress
+        nullptr, // TODO add a delegate to show progress
+        fc)
         .execute(ctx);
     }
 

src/app/file/ase_format.cpp

@@ -290,6 +290,13 @@ bool AseFormat::onLoad(FileOp* fop)
     return false;
 
   Sprite* sprite = delegate.sprite();
+
+  // Assign RgbMap
+  if (sprite->pixelFormat() == IMAGE_INDEXED)
+    sprite->rgbMap(0, Sprite::RgbMapFor(sprite->isOpaque()),
+                   fop->config().rgbMapAlgorithm,
+                   fop->config().fitCriteria);
+
   fop->createDocument(sprite);
 
   if (sprite->colorSpace() != nullptr &&

src/app/file/file.cpp

@@ -1356,6 +1356,11 @@ ImageRef FileOp::sequenceImageToLoad(
       // Add the layer
       sprite->root()->addLayer(layer);
 
+      // Assign RgbMap
+      if (sprite->pixelFormat() == IMAGE_INDEXED)
+        sprite->rgbMap(0, Sprite::RgbMapFor(sprite->isOpaque()),
+                       m_config.rgbMapAlgorithm,
+                       m_config.fitCriteria);
       // Done
       createDocument(sprite);
       m_seq.layer = layer;

src/app/file/file_op_config.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2023  Igara Studio S.A.
+// Copyright (C) 2019-2024  Igara Studio S.A.
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -25,6 +25,7 @@ void FileOpConfig::fillFromPreferences()
   defaultSliceColor = pref.slices.defaultColor();
   workingCS = get_working_rgb_space_from_preferences();
   rgbMapAlgorithm = pref.quantization.rgbmapAlgorithm();
+  fitCriteria = pref.quantization.fitCriteria();
   cacheCompressedTilesets = pref.tileset.cacheCompressedTilesets();
 }
 

src/app/file/file_op_config.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2023  Igara Studio S.A.
+// Copyright (C) 2019-2024  Igara Studio S.A.
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -33,9 +33,14 @@ namespace app {
 
     app::Color defaultSliceColor = app::Color::fromRgb(0, 0, 255);
 
-    // Algorithm used to create a palette from RGB files.
+    // Algorithm used to fit any color into the available palette colors in
+    // Indexed Color Mode.
     doc::RgbMapAlgorithm rgbMapAlgorithm = doc::RgbMapAlgorithm::DEFAULT;
 
+    // Fit criteria used to compare colors during the conversion to
+    // Indexed Color Mode.
+    doc::FitCriteria fitCriteria = doc::FitCriteria::DEFAULT;
+
     // Cache compressed tilesets. When we load a tileset from a
     // .aseprite file, the compressed data will be stored on memory to
     // make the save operation faster (as we can re-use the already

src/app/pref/preferences.cpp

@@ -67,14 +67,6 @@ Preferences::Preferences()
 
   load();
 
-  // Create a connection with the default RgbMapAlgorithm preferences
-  // to change the default algorithm in the "doc" layer.
-  quantization.rgbmapAlgorithm.AfterChange.connect(
-    [](const doc::RgbMapAlgorithm& newValue){
-      doc::Sprite::SetDefaultRgbMapAlgorithm(newValue);
-    });
-  doc::Sprite::SetDefaultRgbMapAlgorithm(quantization.rgbmapAlgorithm());
-
   // Create a connection with the default document preferences grid
   // bounds to sync the default grid bounds for new sprites in the
   // "doc" layer.

src/doc/sprite.cpp

@@ -36,7 +36,6 @@
 
 namespace doc {
 
-static RgbMapAlgorithm g_rgbMapAlgorithm = RgbMapAlgorithm::DEFAULT;
 static gfx::Rect g_defaultGridBounds(0, 0, 16, 16);
 
 // static
@@ -56,18 +55,6 @@ void Sprite::SetDefaultGridBounds(const gfx::Rect& defGridBounds)
     g_defaultGridBounds.h = 1;
 }
 
-// static
-RgbMapAlgorithm Sprite::DefaultRgbMapAlgorithm()
-{
-  return g_rgbMapAlgorithm;
-}
-
-// static
-void Sprite::SetDefaultRgbMapAlgorithm(const RgbMapAlgorithm mapAlgo)
-{
-  g_rgbMapAlgorithm = mapAlgo;
-}
-
 //////////////////////////////////////////////////////////////////////
 // Constructors/Destructor
 
@@ -441,7 +428,7 @@ RgbMap* Sprite::rgbMap(const frame_t frame,
                        const RgbMapFor forLayer) const
 {
   FitCriteria fc = FitCriteria::DEFAULT;
-  RgbMapAlgorithm algo = g_rgbMapAlgorithm;
+  RgbMapAlgorithm algo = RgbMapAlgorithm::DEFAULT;
   if (m_rgbMap) {
     fc = m_rgbMap->fitCriteria();
     algo = m_rgbMap->rgbmapAlgorithm();