diff --git a/OpenRa.BlockCacheVisualizer/Form1.cs b/OpenRa.BlockCacheVisualizer/Form1.cs
index 001757b0a2..127edef200 100644
--- a/OpenRa.BlockCacheVisualizer/Form1.cs
+++ b/OpenRa.BlockCacheVisualizer/Form1.cs
@@ -6,6 +6,7 @@ using System.Drawing;
 using System.Text;
 using System.Windows.Forms;
 using System.IO;
+using System.Drawing.Imaging;
 
 namespace OpenRa.BlockCacheVisualizer
 {
@@ -43,26 +44,51 @@ namespace OpenRa.BlockCacheVisualizer
 			}
 		}
 
-		int MaskColor(Color c, uint mask)
+		uint MaskColor(uint c, uint mask)
 		{
-			uint hax = (uint)c.ToArgb() & mask;
+			uint hax = c & mask;
 
-			hax = ( hax & 0xffff ) | (hax >> 16);
-			hax = (hax & 0xff) | (hax >> 8);
-
-			return (int)hax;
+			hax = (hax & 0xffff) | (hax >> 16);
+			return (hax & 0xff) | (hax >> 8);
 		}
 
 		Bitmap ExtractChannelToBitmap(Bitmap src, Bitmap pal, uint mask)
 		{
-			Bitmap dest = new Bitmap(src.Width / 2, src.Height / 2);
+			Bitmap dest = new Bitmap(src.Width / 2, src.Height / 2, pal.PixelFormat);
 
-			for( int i = 0; i < dest.Width; i++ )
-				for (int j = 0; j < dest.Height; j++)
-				{
-					int index = MaskColor(src.GetPixel(2 * i, 2 * j), mask);
-					dest.SetPixel(i, j, pal.GetPixel(index, 0));
-				}
+			BitmapData destData = dest.LockBits(new Rectangle(new Point(), dest.Size), ImageLockMode.WriteOnly,
+				dest.PixelFormat);
+
+			BitmapData paletteData = pal.LockBits(new Rectangle(new Point(), pal.Size), ImageLockMode.ReadOnly,
+				pal.PixelFormat);
+
+			BitmapData srcData = src.LockBits(new Rectangle(new Point(), src.Size), ImageLockMode.ReadOnly,
+				src.PixelFormat);
+
+			int strideInts = destData.Stride/4;
+			int strideInts2 = srcData.Stride/4;
+
+			unsafe
+			{
+				uint* pdest = (uint*)destData.Scan0.ToPointer();
+				uint* ppal = (uint*)paletteData.Scan0.ToPointer();
+				uint* psrc = (uint*)srcData.Scan0.ToPointer();
+
+				int h = dest.Height; int w = dest.Width;
+
+				for (int j = 0; j < h; j++)
+					for (int i = 0; i < w; i++)
+					{
+						uint srcc = psrc[2 * j * strideInts2 + 2 * i];
+						uint index = MaskColor(srcc, mask);
+						uint data = ppal[index];
+						pdest[j * strideInts + i] = data;
+					}
+			}
+
+			dest.UnlockBits(destData);
+			pal.UnlockBits(paletteData);
+			src.UnlockBits(srcData);
 
 			return dest;
 		}
diff --git a/OpenRa.BlockCacheVisualizer/OpenRa.BlockCacheVisualizer.csproj b/OpenRa.BlockCacheVisualizer/OpenRa.BlockCacheVisualizer.csproj
index b058495057..3d1d52c839 100644
--- a/OpenRa.BlockCacheVisualizer/OpenRa.BlockCacheVisualizer.csproj
+++ b/OpenRa.BlockCacheVisualizer/OpenRa.BlockCacheVisualizer.csproj
@@ -18,6 +18,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
@@ -26,6 +27,7 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />