diff --git a/data/extensions/bayer-matrices/bayer2x2.bmp b/data/extensions/bayer-matrices/bayer2x2.bmp
new file mode 100644
index 000000000..b87d96323
Binary files /dev/null and b/data/extensions/bayer-matrices/bayer2x2.bmp differ
diff --git a/data/extensions/bayer-matrices/bayer4x4.bmp b/data/extensions/bayer-matrices/bayer4x4.bmp
new file mode 100644
index 000000000..7056adfdc
Binary files /dev/null and b/data/extensions/bayer-matrices/bayer4x4.bmp differ
diff --git a/data/extensions/bayer-matrices/bayer8x8.bmp b/data/extensions/bayer-matrices/bayer8x8.bmp
new file mode 100644
index 000000000..45ea27d85
Binary files /dev/null and b/data/extensions/bayer-matrices/bayer8x8.bmp differ
diff --git a/data/extensions/bayer-matrices/package.json b/data/extensions/bayer-matrices/package.json
new file mode 100644
index 000000000..ed09a72d9
--- /dev/null
+++ b/data/extensions/bayer-matrices/package.json
@@ -0,0 +1,26 @@
+{
+  "name": "bayer-matrices",
+  "displayName": "Bayer Matrices for Dithering",
+  "description": "Dithering matrices created by Bryce E. Bayer",
+  "version": "1.0",
+  "publisher": "aseprite",
+  "contributes": {
+    "ditheringMatrices": [
+      {
+        "id": "bayer8x8",
+        "name": "Bayer Matrix 8x8",
+        "path": "./bayer8x8.bmp"
+      },
+      {
+        "id": "bayer4x4",
+        "name": "Bayer Matrix 4x4",
+        "path": "./bayer4x4.bmp"
+      },
+      {
+        "id": "bayer2x2",
+        "name": "Bayer Matrix 2x2",
+        "path": "./bayer2x2.bmp"
+      }
+    ]
+  }
+}
diff --git a/src/app/CMakeLists.txt b/src/app/CMakeLists.txt
index bf599c6bd..50e9628bb 100644
--- a/src/app/CMakeLists.txt
+++ b/src/app/CMakeLists.txt
@@ -382,6 +382,7 @@ add_library(app-lib
   ini_file.cpp
   job.cpp
   launcher.cpp
+  load_matrix.cpp
   log.cpp
   loop_tag.cpp
   modules.cpp
diff --git a/src/app/commands/cmd_change_pixel_format.cpp b/src/app/commands/cmd_change_pixel_format.cpp
index 4de0a6325..2009d4525 100644
--- a/src/app/commands/cmd_change_pixel_format.cpp
+++ b/src/app/commands/cmd_change_pixel_format.cpp
@@ -14,7 +14,8 @@
 #include "app/commands/command.h"
 #include "app/commands/params.h"
 #include "app/context_access.h"
-#include "app/file/file.h"
+#include "app/extensions.h"
+#include "app/load_matrix.h"
 #include "app/modules/editors.h"
 #include "app/modules/gui.h"
 #include "app/modules/palettes.h"
@@ -376,45 +377,21 @@ void ChangePixelFormatCommand::onLoadParams(const Params& params)
     m_ditheringAlgorithm = render::DitheringAlgorithm::None;
 
   std::string matrix = params.get("dithering-matrix");
-  // TODO object slicing here (from BayerMatrix -> DitheringMatrix
   if (!matrix.empty()) {
-    if (matrix == "bayer2x2")
-      m_ditheringMatrix = render::BayerMatrix(2);
-    else if (matrix == "bayer4x4")
-      m_ditheringMatrix = render::BayerMatrix(4);
-    else if (matrix == "bayer8x8")
-      m_ditheringMatrix = render::BayerMatrix(8);
-    else {
-      // Load a matrix from a file
-      base::UniquePtr<doc::Document> doc(load_document(nullptr, matrix));
-      if (doc) {
-        // Flatten layers
-        doc::Sprite* spr = doc->sprite();
-        app::Context ctx;
-        cmd::FlattenLayers(spr).execute(&ctx);
-
-        const doc::Layer* lay = spr->root()->firstLayer();
-        const doc::Image* img = (lay && lay->cel(0) ?
-                                 lay->cel(0)->image(): nullptr);
-        if (img) {
-          const int w = spr->width();
-          const int h = spr->height();
-          m_ditheringMatrix = render::DitheringMatrix(h, w);
-          for (int i=0; i<h; ++i)
-            for (int j=0; j<w; ++j)
-              m_ditheringMatrix(i, j) = img->getPixel(j, i);
-          m_ditheringMatrix.calcMaxValue();
-        }
-        else {
-          m_ditheringMatrix = render::DitheringMatrix();
-        }
-      }
-      else
-        throw std::runtime_error("Invalid matrix name");
+    // Try to get the matrix from the extensions
+    const render::DitheringMatrix* knownMatrix =
+      App::instance()->extensions().ditheringMatrix(matrix);
+    if (knownMatrix) {
+      m_ditheringMatrix = *knownMatrix;
+    }
+    // Then, if the matrix doesn't exist we try to load it from a file
+    else if (!load_dithering_matrix_from_sprite(matrix, m_ditheringMatrix)) {
+      throw std::runtime_error("Invalid matrix name");
     }
   }
   // Default dithering matrix is BayerMatrix(8)
   else {
+    // TODO object slicing here (from BayerMatrix -> DitheringMatrix)
     m_ditheringMatrix = render::BayerMatrix(8);
   }
 }
diff --git a/src/app/extensions.cpp b/src/app/extensions.cpp
index e9b603046..799c2f7b8 100644
--- a/src/app/extensions.cpp
+++ b/src/app/extensions.cpp
@@ -11,12 +11,14 @@
 #include "app/extensions.h"
 
 #include "app/ini_file.h"
+#include "app/load_matrix.h"
 #include "app/pref/preferences.h"
 #include "app/resource_finder.h"
 #include "base/exception.h"
 #include "base/file_handle.h"
 #include "base/fs.h"
 #include "base/unique_ptr.h"
+#include "render/dithering_matrix.h"
 
 #include "archive.h"
 #include "archive_entry.h"
@@ -153,6 +155,21 @@ private:
 
 } // anonymous namespace
 
+const render::DitheringMatrix& Extension::DitheringMatrixInfo::matrix() const
+{
+  if (!m_matrix) {
+    m_matrix = new render::DitheringMatrix;
+    load_dithering_matrix_from_sprite(m_path, *m_matrix);
+  }
+  return *m_matrix;
+}
+
+void Extension::DitheringMatrixInfo::destroyMatrix()
+{
+  if (m_matrix)
+    delete m_matrix;
+}
+
 Extension::Extension(const std::string& path,
                      const std::string& name,
                      const std::string& displayName,
@@ -167,6 +184,13 @@ Extension::Extension(const std::string& path,
 {
 }
 
+Extension::~Extension()
+{
+  // Delete all matrices
+  for (auto& it : m_ditheringMatrices)
+    it.second.destroyMatrix();
+}
+
 void Extension::addTheme(const std::string& id, const std::string& path)
 {
   m_themes[id] = path;
@@ -177,6 +201,14 @@ void Extension::addPalette(const std::string& id, const std::string& path)
   m_palettes[id] = path;
 }
 
+void Extension::addDitheringMatrix(const std::string& id,
+                                   const std::string& path,
+                                   const std::string& name)
+{
+  DitheringMatrixInfo info(path, name);
+  m_ditheringMatrices[id] = info;
+}
+
 bool Extension::canBeDisabled() const
 {
   return (m_isEnabled &&
@@ -347,6 +379,32 @@ ExtensionItems Extensions::palettes() const
   return palettes;
 }
 
+const render::DitheringMatrix* Extensions::ditheringMatrix(const std::string& matrixId)
+{
+  for (auto ext : m_extensions) {
+    if (!ext->isEnabled())      // Ignore disabled themes
+      continue;
+
+    auto it = ext->m_ditheringMatrices.find(matrixId);
+    if (it != ext->m_ditheringMatrices.end())
+      return &it->second.matrix();
+  }
+  return nullptr;
+}
+
+std::vector<Extension::DitheringMatrixInfo> Extensions::ditheringMatrices()
+{
+  std::vector<Extension::DitheringMatrixInfo> result;
+  for (auto ext : m_extensions) {
+    if (!ext->isEnabled())      // Ignore disabled themes
+      continue;
+
+    for (auto it : ext->m_ditheringMatrices)
+      result.push_back(it.second);
+  }
+  return result;
+}
+
 void Extensions::enableExtension(Extension* extension, const bool state)
 {
   extension->enable(state);
@@ -493,6 +551,25 @@ Extension* Extensions::loadExtension(const std::string& path,
         extension->addPalette(palId, palPath);
       }
     }
+
+    // Dithering matrices
+    auto ditheringMatrices = contributes["ditheringMatrices"];
+    if (ditheringMatrices.is_array()) {
+      for (const auto& ditheringMatrix : ditheringMatrices.get_array()) {
+        std::string matId = ditheringMatrix.at("id").get_string();
+        std::string matPath = ditheringMatrix.at("path").get_string();
+        std::string matName = ditheringMatrix.at("name").get_string();
+
+        // The path must be always relative to the extension
+        matPath = base::join_path(path, matPath);
+
+        LOG("EXT: New dithering matrix '%s' in '%s'\n",
+            matId.c_str(),
+            matPath.c_str());
+
+        extension->addDitheringMatrix(matId, matPath, matName);
+      }
+    }
   }
 
   if (extension)
@@ -502,8 +579,9 @@ Extension* Extensions::loadExtension(const std::string& path,
 
 void Extensions::generateExtensionSignals(Extension* extension)
 {
-  if (!extension->themes().empty()) ThemesChange(extension);
-  if (!extension->palettes().empty()) PalettesChange(extension);
+  if (extension->hasThemes()) ThemesChange(extension);
+  if (extension->hasPalettes()) PalettesChange(extension);
+  if (extension->hasDitheringMatrices()) DitheringMatricesChange(extension);
 }
 
 } // namespace app
diff --git a/src/app/extensions.h b/src/app/extensions.h
index 610c32fa4..5ff043e61 100644
--- a/src/app/extensions.h
+++ b/src/app/extensions.h
@@ -8,12 +8,17 @@
 #define APP_EXTENSIONS_H_INCLUDED
 #pragma once
 
+#include "base/unique_ptr.h"
 #include "obs/signal.h"
 
 #include <map>
 #include <string>
 #include <vector>
 
+namespace render {
+  class DitheringMatrix;
+}
+
 namespace app {
 
   // Key=theme/palette/etc. id
@@ -25,11 +30,29 @@ namespace app {
   class Extension {
     friend class Extensions;
   public:
+    class DitheringMatrixInfo {
+    public:
+      DitheringMatrixInfo() : m_matrix(nullptr) { }
+      DitheringMatrixInfo(const std::string& path,
+                          const std::string& name)
+        : m_path(path), m_name(name), m_matrix(nullptr) { }
+
+      const std::string& name() const { return m_name; }
+      const render::DitheringMatrix& matrix() const;
+      void destroyMatrix();
+
+    private:
+      std::string m_path;
+      std::string m_name;
+      mutable render::DitheringMatrix* m_matrix;
+    };
+
     Extension(const std::string& path,
               const std::string& name,
               const std::string& displayName,
               const bool isEnabled,
               const bool isBuiltinExtension);
+    ~Extension();
 
     const std::string& path() const { return m_path; }
     const std::string& name() const { return m_name; }
@@ -40,12 +63,19 @@ namespace app {
 
     void addTheme(const std::string& id, const std::string& path);
     void addPalette(const std::string& id, const std::string& path);
+    void addDitheringMatrix(const std::string& id,
+                            const std::string& path,
+                            const std::string& name);
 
     bool isEnabled() const { return m_isEnabled; }
     bool isInstalled() const { return m_isInstalled; }
     bool canBeDisabled() const;
     bool canBeUninstalled() const;
 
+    bool hasThemes() const { return !m_themes.empty(); }
+    bool hasPalettes() const { return !m_palettes.empty(); }
+    bool hasDitheringMatrices() const { return !m_ditheringMatrices.empty(); }
+
   private:
     void enable(const bool state);
     void uninstall();
@@ -55,6 +85,7 @@ namespace app {
 
     ExtensionItems m_themes;
     ExtensionItems m_palettes;
+    std::map<std::string, DitheringMatrixInfo> m_ditheringMatrices;
     std::string m_path;
     std::string m_name;
     std::string m_displayName;
@@ -81,10 +112,13 @@ namespace app {
     std::string themePath(const std::string& themeId);
     std::string palettePath(const std::string& palId);
     ExtensionItems palettes() const;
+    const render::DitheringMatrix* ditheringMatrix(const std::string& matrixId);
+    std::vector<Extension::DitheringMatrixInfo> ditheringMatrices();
 
     obs::signal<void(Extension*)> NewExtension;
     obs::signal<void(Extension*)> ThemesChange;
     obs::signal<void(Extension*)> PalettesChange;
+    obs::signal<void(Extension*)> DitheringMatricesChange;
 
   private:
     Extension* loadExtension(const std::string& path,
diff --git a/src/app/load_matrix.cpp b/src/app/load_matrix.cpp
new file mode 100644
index 000000000..09b11e9c2
--- /dev/null
+++ b/src/app/load_matrix.cpp
@@ -0,0 +1,52 @@
+// Aseprite
+// Copyright (C) 2017  David Capello
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/load_matrix.h"
+
+#include "app/context.h"
+#include "app/document.h"
+#include "app/file/file.h"
+#include "doc/layer.h"
+#include "doc/sprite.h"
+#include "render/dithering_matrix.h"
+
+namespace app {
+
+bool load_dithering_matrix_from_sprite(
+  const std::string& filename,
+  render::DitheringMatrix& matrix)
+{
+  base::UniquePtr<doc::Document> doc(load_document(nullptr, filename));
+  if (!doc)
+    return false;
+
+  doc::Sprite* spr = doc->sprite();
+  const doc::Layer* lay = (spr && spr->root() ? spr->root()->firstLayer():
+                                                nullptr);
+  const doc::Image* img = (lay && lay->cel(0) ? lay->cel(0)->image():
+                                                nullptr);
+  if (img) {
+    const int w = spr->width();
+    const int h = spr->height();
+    matrix = render::DitheringMatrix(h, w);
+    for (int i=0; i<h; ++i)
+      for (int j=0; j<w; ++j)
+        matrix(i, j) = img->getPixel(j, i);
+
+    matrix.calcMaxValue();
+  }
+  else {
+    matrix = render::DitheringMatrix();
+  }
+
+  return true;
+}
+
+} // namespace app
diff --git a/src/app/load_matrix.h b/src/app/load_matrix.h
new file mode 100644
index 000000000..45b6900ff
--- /dev/null
+++ b/src/app/load_matrix.h
@@ -0,0 +1,23 @@
+// Aseprite
+// Copyright (C) 2017  David Capello
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_LOAD_MATRIX_H_INCLUDED
+#define APP_LOAD_MATRIX_H_INCLUDED
+#pragma once
+
+namespace render {
+  class DitheringMatrix;
+};
+
+namespace app {
+
+  bool load_dithering_matrix_from_sprite(
+    const std::string& filename,
+    render::DitheringMatrix& matrix);
+
+} // namespace app
+
+#endif
diff --git a/src/app/ui/dithering_selector.cpp b/src/app/ui/dithering_selector.cpp
index 0fa0c04ea..dbb30c8d3 100644
--- a/src/app/ui/dithering_selector.cpp
+++ b/src/app/ui/dithering_selector.cpp
@@ -10,6 +10,8 @@
 
 #include "app/ui/dithering_selector.h"
 
+#include "app/app.h"
+#include "app/extensions.h"
 #include "app/modules/palettes.h"
 #include "app/ui/skin/skin_theme.h"
 #include "base/bind.h"
@@ -157,35 +159,53 @@ private:
 } // anonymous namespace
 
 DitheringSelector::DitheringSelector(Type type)
+  : m_type(type)
 {
-  setUseCustomWidget(true);
+  Extensions& extensions = App::instance()->extensions();
 
-  switch (type) {
+  // If an extension with "ditheringMatrices" is disable/enable, we
+  // regenerate this DitheringSelector
+  m_extChanges =
+    extensions.DitheringMatricesChange.connect(
+      base::Bind<void>(&DitheringSelector::regenerate, this));
+
+  setUseCustomWidget(true);
+  regenerate();
+}
+
+void DitheringSelector::regenerate()
+{
+  removeAllItems();
+
+  Extensions& extensions = App::instance()->extensions();
+  auto ditheringMatrices = extensions.ditheringMatrices();
+
+  switch (m_type) {
     case SelectBoth:
       addItem(new DitherItem(render::DitheringAlgorithm::None,
                              render::DitheringMatrix(), "No Dithering"));
-      addItem(new DitherItem(render::DitheringAlgorithm::Ordered,
-                             render::BayerMatrix(8), "Ordered Dithering - Bayer Matrix 8x8"));
-      addItem(new DitherItem(render::DitheringAlgorithm::Ordered,
-                             render::BayerMatrix(4), "Ordered Dithering - Bayer Matrix 4x4"));
-      addItem(new DitherItem(render::DitheringAlgorithm::Ordered,
-                             render::BayerMatrix(2), "Ordered Dithering - Bayer Matrix 2x2"));
-      addItem(new DitherItem(render::DitheringAlgorithm::Old,
-                             render::BayerMatrix(8), "Old Dithering - Bayer Matrix 8x8"));
-      addItem(new DitherItem(render::DitheringAlgorithm::Old,
-                             render::BayerMatrix(4), "Old Dithering - Bayer Matrix 4x4"));
-      addItem(new DitherItem(render::DitheringAlgorithm::Old,
-                             render::BayerMatrix(2), "Old Dithering - Bayer Matrix 2x2"));
+      for (const auto& it : ditheringMatrices) {
+        addItem(
+          new DitherItem(
+            render::DitheringAlgorithm::Ordered,
+            it.matrix(),
+            "Ordered Dithering+" + it.name()));
+      }
+      for (const auto& it : ditheringMatrices) {
+        addItem(
+          new DitherItem(
+            render::DitheringAlgorithm::Old,
+            it.matrix(),
+            "Old Dithering+" + it.name()));
+      }
       break;
     case SelectMatrix:
       addItem(new DitherItem(render::DitheringMatrix(), "No Dithering"));
-      addItem(new DitherItem(render::BayerMatrix(8), "Bayer Matrix 8x8"));
-      addItem(new DitherItem(render::BayerMatrix(4), "Bayer Matrix 4x4"));
-      addItem(new DitherItem(render::BayerMatrix(2), "Bayer Matrix 2x2"));
+      for (auto& it : ditheringMatrices)
+        addItem(new DitherItem(it.matrix(), it.name()));
       break;
   }
 
-
   setSelectedItemIndex(0);
   setSizeHint(getItem(0)->sizeHint());
 }
diff --git a/src/app/ui/dithering_selector.h b/src/app/ui/dithering_selector.h
index 2d7a01d01..686502351 100644
--- a/src/app/ui/dithering_selector.h
+++ b/src/app/ui/dithering_selector.h
@@ -8,6 +8,7 @@
 #define APP_UI_DITHERING_SELECTOR_H_INCLUDED
 #pragma once
 
+#include "obs/connection.h"
 #include "render/dithering_algorithm.h"
 #include "render/ordered_dither.h"
 #include "ui/box.h"
@@ -26,6 +27,12 @@ namespace app {
 
     render::DitheringAlgorithm ditheringAlgorithm();
     render::DitheringMatrix ditheringMatrix();
+
+  private:
+    void regenerate();
+
+    Type m_type;
+    obs::scoped_connection m_extChanges;
   };
 
 } // namespace app