diff --git a/src/app/color.cpp b/src/app/color.cpp
index f06a1a200..5c5d05fb7 100644
--- a/src/app/color.cpp
+++ b/src/app/color.cpp
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2020  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -255,7 +256,7 @@ std::string Color::toHumanReadableString(PixelFormat pixelFormat, HumanReadableS
 
           if (pixelFormat == IMAGE_INDEXED)
             result << " Index "
-                   << color_utils::color_for_image(*this, pixelFormat);
+                   << color_utils::color_for_image(*this, IMAGE_INDEXED);
         }
         break;
 
@@ -270,7 +271,7 @@ std::string Color::toHumanReadableString(PixelFormat pixelFormat, HumanReadableS
                  << MID(0, int(m_value.hsv.v*100.0), 100) << "%";
 
           if (pixelFormat == IMAGE_INDEXED)
-            result << " Index " << color_utils::color_for_image(*this, pixelFormat);
+            result << " Index " << color_utils::color_for_image(*this, IMAGE_INDEXED);
 
           result << " (RGB "
                  << getRed() << " "
@@ -290,7 +291,7 @@ std::string Color::toHumanReadableString(PixelFormat pixelFormat, HumanReadableS
                  << MID(0, int(m_value.hsl.l*100.0), 100) << "%";
 
           if (pixelFormat == IMAGE_INDEXED)
-            result << " Index " << color_utils::color_for_image(*this, pixelFormat);
+            result << " Index " << color_utils::color_for_image(*this, IMAGE_INDEXED);
 
           result << " (RGB "
                  << getRed() << " "
diff --git a/src/app/color_utils.cpp b/src/app/color_utils.cpp
index f839925e9..5d3bd3e51 100644
--- a/src/app/color_utils.cpp
+++ b/src/app/color_utils.cpp
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2020  Igara Studio S.A.
 // Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
@@ -89,6 +90,28 @@ doc::color_t color_utils::color_for_image(const app::Color& color, PixelFormat f
 
   doc::color_t c = -1;
 
+  switch (format) {
+    case IMAGE_RGB:
+      c = doc::rgba(color.getRed(), color.getGreen(), color.getBlue(), color.getAlpha());
+      break;
+    case IMAGE_GRAYSCALE:
+      c = doc::graya(color.getGray(), color.getAlpha());
+      break;
+    case IMAGE_INDEXED:
+      c = color.getIndex();
+      break;
+  }
+
+  return c;
+}
+
+doc::color_t color_utils::color_for_image_without_alpha(const app::Color& color, PixelFormat format)
+{
+  if (color.getType() == app::Color::MaskType)
+    return 0;
+
+  doc::color_t c = -1;
+
   switch (format) {
     case IMAGE_RGB:
       c = doc::rgba(color.getRed(), color.getGreen(), color.getBlue(), 255);
diff --git a/src/app/color_utils.h b/src/app/color_utils.h
index 7a790e6c2..767d8c97b 100644
--- a/src/app/color_utils.h
+++ b/src/app/color_utils.h
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2020  Igara Studio S.A.
 // Copyright (C) 2001-2015  David Capello
 //
 // This program is distributed under the terms of
@@ -26,6 +27,7 @@ namespace app {
 
     gfx::Color color_for_ui(const app::Color& color);
     doc::color_t color_for_image(const app::Color& color, doc::PixelFormat format);
+    doc::color_t color_for_image_without_alpha(const app::Color& color, doc::PixelFormat format);
     doc::color_t color_for_layer(const app::Color& color, doc::Layer* layer);
     doc::color_t color_for_target_mask(const app::Color& color, const ColorTarget& colorTarget);
     doc::color_t color_for_target(const app::Color& color, const ColorTarget& colorTarget);
diff --git a/src/app/commands/cmd_mask_by_color.cpp b/src/app/commands/cmd_mask_by_color.cpp
index 56d49f19f..25d86a698 100644
--- a/src/app/commands/cmd_mask_by_color.cpp
+++ b/src/app/commands/cmd_mask_by_color.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -207,7 +207,8 @@ Mask* MaskByColorCommand::generateMask(const Mask& origMask,
                                        int xpos, int ypos,
                                        gen::SelectionMode mode)
 {
-  int color = color_utils::color_for_image(m_buttonColor->getColor(), sprite->pixelFormat());
+  int color = color_utils::color_for_image(m_buttonColor->getColor(),
+                                           sprite->pixelFormat());
   int tolerance = m_sliderTolerance->getValue();
 
   std::unique_ptr<Mask> mask(new Mask());
diff --git a/src/app/script/brush_class.cpp b/src/app/script/brush_class.cpp
index edfe2b718..28fdfaa56 100644
--- a/src/app/script/brush_class.cpp
+++ b/src/app/script/brush_class.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2019-2020  Igara Studio S.A.
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -127,8 +127,10 @@ int Brush_gc(lua_State* L)
 int Brush_setFgColor(lua_State* L)
 {
   auto obj = get_obj<BrushObj>(L, 1);
-  if (obj->brush) {
-    const doc::color_t color = convert_args_into_pixel_color(L, 2);
+  if (obj->brush &&
+      obj->brush->image()) {
+    const doc::color_t color = convert_args_into_pixel_color(
+      L, 2, obj->brush->image()->pixelFormat());
     obj->brush->setImageColor(Brush::ImageColor::MainColor, color);
   }
   return 0;
@@ -137,9 +139,12 @@ int Brush_setFgColor(lua_State* L)
 int Brush_setBgColor(lua_State* L)
 {
   auto obj = get_obj<BrushObj>(L, 1);
-  if (obj->brush) {
-    const doc::color_t color = convert_args_into_pixel_color(L, 2);
-    obj->brush->setImageColor(Brush::ImageColor::BackgroundColor, color);
+  if (obj->brush &&
+      obj->brush->image()) {
+    const doc::color_t color = convert_args_into_pixel_color(
+      L, 2, obj->brush->image()->pixelFormat());
+    obj->brush->setImageColor(
+      Brush::ImageColor::BackgroundColor, color);
   }
   return 0;
 }
diff --git a/src/app/script/color_class.cpp b/src/app/script/color_class.cpp
index ee0147a5d..ae5542955 100644
--- a/src/app/script/color_class.cpp
+++ b/src/app/script/color_class.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2019-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -481,10 +481,11 @@ app::Color convert_args_into_color(lua_State* L, int index)
   return Color_new(L, index);
 }
 
-doc::color_t convert_args_into_pixel_color(lua_State* L, int index)
+doc::color_t convert_args_into_pixel_color(lua_State* L, int index,
+                                           const doc::PixelFormat pixelFormat)
 {
   app::Color color = convert_args_into_color(L, index);
-  return color_utils::color_for_image(color, doc::IMAGE_RGB);
+  return color_utils::color_for_image(color, pixelFormat);
 }
 
 } // namespace script
diff --git a/src/app/script/engine.h b/src/app/script/engine.h
index dfec00fb0..0860e773e 100644
--- a/src/app/script/engine.h
+++ b/src/app/script/engine.h
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -18,6 +18,7 @@
 #include "doc/brush.h"
 #include "doc/frame.h"
 #include "doc/object_ids.h"
+#include "doc/pixel_format.h"
 #include "gfx/fwd.h"
 
 #include <cstdio>
@@ -149,7 +150,8 @@ namespace app {
   gfx::Rect convert_args_into_rect(lua_State* L, int index);
   gfx::Size convert_args_into_size(lua_State* L, int index);
   app::Color convert_args_into_color(lua_State* L, int index);
-  doc::color_t convert_args_into_pixel_color(lua_State* L, int index);
+  doc::color_t convert_args_into_pixel_color(lua_State* L, int index,
+                                             const doc::PixelFormat pixelFormat);
   doc::Palette* get_palette_from_arg(lua_State* L, int index);
   doc::Image* may_get_image_from_arg(lua_State* L, int index);
   doc::Image* get_image_from_arg(lua_State* L, int index);
diff --git a/src/app/script/image_class.cpp b/src/app/script/image_class.cpp
index a0fb28d44..0459be13b 100644
--- a/src/app/script/image_class.cpp
+++ b/src/app/script/image_class.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2015-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -164,7 +164,7 @@ int Image_clear(lua_State* L)
   else if (lua_isinteger(L, 2))
     color = lua_tointeger(L, 2);
   else
-    color = convert_args_into_pixel_color(L, 2);
+    color = convert_args_into_pixel_color(L, 2, img->pixelFormat());
   doc::clear_image(img, color);
   return 0;
 }
@@ -172,14 +172,15 @@ int Image_clear(lua_State* L)
 int Image_drawPixel(lua_State* L)
 {
   auto obj = get_obj<ImageObj>(L, 1);
+  auto img = obj->image(L);
   const int x = lua_tointeger(L, 2);
   const int y = lua_tointeger(L, 3);
   doc::color_t color;
   if (lua_isinteger(L, 4))
     color = lua_tointeger(L, 4);
   else
-    color = convert_args_into_pixel_color(L, 4);
-  doc::put_pixel(obj->image(L), x, y, color);
+    color = convert_args_into_pixel_color(L, 4, img->pixelFormat());
+  doc::put_pixel(img, x, y, color);
   return 0;
 }
 
@@ -304,7 +305,7 @@ int Image_isPlain(lua_State* L)
   else if (lua_isinteger(L, 2))
     color = lua_tointeger(L, 2);
   else
-    color = convert_args_into_pixel_color(L, 2);
+    color = convert_args_into_pixel_color(L, 2, img->pixelFormat());
 
   bool res = doc::is_plain_image(img, color);
   lua_pushboolean(L, res);
diff --git a/src/app/script/palette_class.cpp b/src/app/script/palette_class.cpp
index aef25b23d..05cf8ec8b 100644
--- a/src/app/script/palette_class.cpp
+++ b/src/app/script/palette_class.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -201,7 +201,8 @@ int Palette_setColor(lua_State* L)
   if (i < 0 || i >= int(pal->size()))
     return luaL_error(L, "index out of bounds %d", i);
 
-  doc::color_t docColor = convert_args_into_pixel_color(L, 3);
+  doc::color_t docColor = convert_args_into_pixel_color(
+    L, 3, doc::IMAGE_RGB);
 
   if (auto sprite = obj->sprite(L)) {
     // Nothing to do
diff --git a/src/app/script/userdata.h b/src/app/script/userdata.h
index 529bc8b47..4d7642c38 100644
--- a/src/app/script/userdata.h
+++ b/src/app/script/userdata.h
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -67,7 +67,7 @@ int UserData_set_text(lua_State* L) {
 template<typename T>
 int UserData_set_color(lua_State* L) {
   auto obj = get_docobj<T>(L, 1);
-  doc::color_t docColor = convert_args_into_pixel_color(L, 2);
+  doc::color_t docColor = convert_args_into_pixel_color(L, 2, doc::IMAGE_RGB);
   auto wud = get_WithUserData<T>(obj);
   UserData ud = wud->userData();
   ud.setColor(docColor);
diff --git a/src/app/ui/editor/editor_render.cpp b/src/app/ui/editor/editor_render.cpp
index 35eaa28aa..45df1125b 100644
--- a/src/app/ui/editor/editor_render.cpp
+++ b/src/app/ui/editor/editor_render.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2019-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -88,8 +88,8 @@ void EditorRender::setupBackground(Doc* doc, doc::PixelFormat pixelFormat)
 
   m_render->setBgType(bgType);
   m_render->setBgZoom(docPref.bg.zoom());
-  m_render->setBgColor1(color_utils::color_for_image(docPref.bg.color1(), pixelFormat));
-  m_render->setBgColor2(color_utils::color_for_image(docPref.bg.color2(), pixelFormat));
+  m_render->setBgColor1(color_utils::color_for_image_without_alpha(docPref.bg.color1(), pixelFormat));
+  m_render->setBgColor2(color_utils::color_for_image_without_alpha(docPref.bg.color2(), pixelFormat));
   m_render->setBgCheckedSize(tile);
 }