diff --git a/src/app/script/image_class.cpp b/src/app/script/image_class.cpp
index a5ab77e11..804510ff2 100644
--- a/src/app/script/image_class.cpp
+++ b/src/app/script/image_class.cpp
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2018  Igara Studio S.A.
 // Copyright (C) 2015-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -54,6 +55,7 @@ int Image_new(lua_State* L)
     spec.setColorMode((doc::ColorMode)colorMode);
   }
   doc::ImageRef image(doc::Image::create(spec));
+  doc::clear_image(image.get(), spec.maskColor());
   push_new<ImageObj>(L, image, nullptr);
   return 1;
 }
@@ -76,7 +78,9 @@ int Image_clear(lua_State* L)
 {
   auto obj = get_obj<ImageObj>(L, 1);
   doc::color_t color;
-  if (lua_isinteger(L, 2))
+  if (lua_isnone(L, 2))
+    color = obj->image.get()->maskColor();
+  else if (lua_isinteger(L, 2))
     color = lua_tointeger(L, 2);
   else
     color = convert_args_into_pixel_color(L, 2);
diff --git a/src/doc/image.cpp b/src/doc/image.cpp
index 4eb6c4a80..dcfa8bf89 100644
--- a/src/doc/image.cpp
+++ b/src/doc/image.cpp
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2018 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -19,9 +20,9 @@
 
 namespace doc {
 
-Image::Image(PixelFormat format, int width, int height)
+Image::Image(const ImageSpec& spec)
   : Object(ObjectType::Image)
-  , m_spec((ColorMode)format, width, height, 0)
+  , m_spec(spec)
 {
 }
 
@@ -48,21 +49,20 @@ int Image::getRowStrideSize(int pixels_per_row) const
 Image* Image::create(PixelFormat format, int width, int height,
                      const ImageBufferPtr& buffer)
 {
-  switch (format) {
-    case IMAGE_RGB:       return new ImageImpl<RgbTraits>(width, height, buffer);
-    case IMAGE_GRAYSCALE: return new ImageImpl<GrayscaleTraits>(width, height, buffer);
-    case IMAGE_INDEXED:   return new ImageImpl<IndexedTraits>(width, height, buffer);
-    case IMAGE_BITMAP:    return new ImageImpl<BitmapTraits>(width, height, buffer);
-  }
-  return NULL;
+  return Image::create(ImageSpec((ColorMode)format, width, height, 0), buffer);
 }
 
 // static
 Image* Image::create(const ImageSpec& spec,
                      const ImageBufferPtr& buffer)
 {
-  return Image::create((PixelFormat)spec.colorMode(),
-                       spec.width(), spec.height(), buffer);
+  switch (spec.colorMode()) {
+    case ColorMode::RGB:       return new ImageImpl<RgbTraits>(spec, buffer);
+    case ColorMode::GRAYSCALE: return new ImageImpl<GrayscaleTraits>(spec, buffer);
+    case ColorMode::INDEXED:   return new ImageImpl<IndexedTraits>(spec, buffer);
+    case ColorMode::BITMAP:    return new ImageImpl<BitmapTraits>(spec, buffer);
+  }
+  return nullptr;
 }
 
 // static
diff --git a/src/doc/image.h b/src/doc/image.h
index 04aaf28f6..c95587f99 100644
--- a/src/doc/image.h
+++ b/src/doc/image.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2018 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -85,7 +86,7 @@ namespace doc {
     virtual void blendRect(int x1, int y1, int x2, int y2, color_t color, int opacity) = 0;
 
   protected:
-    Image(PixelFormat format, int width, int height);
+    Image(const ImageSpec& spec);
 
   private:
     ImageSpec m_spec;
diff --git a/src/doc/image_impl.h b/src/doc/image_impl.h
index bc0240085..0a8304fc5 100644
--- a/src/doc/image_impl.h
+++ b/src/doc/image_impl.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2018 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -55,14 +56,16 @@ namespace doc {
       return (address_t)(m_rows[y] + x / (Traits::pixels_per_byte == 0 ? 1 : Traits::pixels_per_byte));
     }
 
-    ImageImpl(int width, int height,
+    ImageImpl(const ImageSpec& spec,
               const ImageBufferPtr& buffer)
-      : Image(static_cast<PixelFormat>(Traits::pixel_format), width, height)
+      : Image(spec)
       , m_buffer(buffer)
     {
-      std::size_t for_rows = sizeof(address_t) * height;
-      std::size_t rowstride_bytes = Traits::getRowStrideBytes(width);
-      std::size_t required_size = for_rows + rowstride_bytes*height;
+      ASSERT(Traits::color_mode == spec.colorMode());
+
+      std::size_t for_rows = sizeof(address_t) * spec.height();
+      std::size_t rowstride_bytes = Traits::getRowStrideBytes(spec.width());
+      std::size_t required_size = for_rows + rowstride_bytes*spec.height();
 
       if (!m_buffer)
         m_buffer.reset(new ImageBuffer(required_size));
@@ -73,7 +76,7 @@ namespace doc {
       m_bits = (address_t)(m_buffer->buffer() + for_rows);
 
       address_t addr = m_bits;
-      for (int y=0; y<height; ++y) {
+      for (int y=0; y<spec.height(); ++y) {
         m_rows[y] = addr;
         addr = (address_t)(((uint8_t*)addr) + rowstride_bytes);
       }