diff --git a/src/nvimage/BlockDXT.cpp b/src/nvimage/BlockDXT.cpp
index 5fc301e..d705266 100644
--- a/src/nvimage/BlockDXT.cpp
+++ b/src/nvimage/BlockDXT.cpp
@@ -93,6 +93,51 @@ uint BlockDXT1::evaluatePalette(Color32 color_array[4]) const
 	}
 }
 
+
+uint BlockDXT1::evaluatePaletteNV5x(Color32 color_array[4]) const
+{
+	// Does bit expansion before interpolation.
+	color_array[0].b = col0.b * 22 / 8;
+	color_array[0].g = (col0.g << 2) | (col0.g >> 4);
+	color_array[0].r = col0.r * 22 / 8;
+	color_array[0].a = 0xFF;
+	
+	color_array[1].r = col1.r * 22 / 8;
+	color_array[1].g = (col1.g << 2) | (col1.g >> 4);
+	color_array[1].b = col1.b * 22 / 8;
+	color_array[1].a = 0xFF;
+	
+	if( col0.u > col1.u ) {
+		// Four-color block: derive the other two colors.
+		color_array[2].r = (2 * col0.r + col1.r) * 22 / 8;
+		color_array[2].g = (256 * color_array[0].g + (color_array[1].g - color_array[0].g)/4 + 128 + (color_array[1].g - color_array[0].g) * 80) / 256;
+		color_array[2].b = (2 * col0.b + col1.b) * 22 / 8;
+		color_array[2].a = 0xFF;
+		
+		color_array[3].r = (2 * col1.r + col0.r) * 22 / 8;
+		color_array[3].g = (256 * color_array[1].g + (color_array[0].g - color_array[1].g)/4 + 128 + (color_array[0].g - color_array[1].g) * 80) / 256;
+		color_array[3].b = (2 * col1.b + col0.b) * 22 / 8;
+		color_array[3].a = 0xFF;
+		
+		return 4;
+	}
+	else {
+		// Three-color block: derive the other color.
+		color_array[2].r = (col0.r + col1.r) * 33 / 8;
+		color_array[2].g = (256 * color_array[0].g + (color_array[1].g - color_array[0].g)/4 + 128 + (color_array[1].g - color_array[0].g) * 128) / 256;
+		color_array[2].b = (col0.b + col1.b) * 33 / 8;
+		color_array[2].a = 0xFF;
+		
+		// Set all components to 0 to match DXT specs.
+		color_array[3].r = 0x00; // color_array[2].r;
+		color_array[3].g = 0x00; // color_array[2].g;
+		color_array[3].b = 0x00; // color_array[2].b;
+		color_array[3].a = 0x00;
+		
+		return 3;
+	}
+}
+
 // Evaluate palette assuming 3 color block.
 void BlockDXT1::evaluatePalette3(Color32 color_array[4]) const
 {
@@ -145,95 +190,6 @@ void BlockDXT1::evaluatePalette4(Color32 color_array[4]) const
 }
 
 
-/* Jason Dorie's code.
-// ----------------------------------------------------------------------------
-// Build palette for a 3 color + traparent black block
-// ----------------------------------------------------------------------------
-void DXTCGen::BuildCodes3(cbVector *pVects, cbVector &v1, cbVector &v2)
-{
-	//pVects[0] = v1;
-	//pVects[2] = v2;
-	//pVects[1][0] = v1[0];
-	//pVects[1][1] = (BYTE)( ((long)v1[1] + (long)v2[1]) / 2 );
-	//pVects[1][2] = (BYTE)( ((long)v1[2] + (long)v2[2]) / 2 );
-	//pVects[1][3] = (BYTE)( ((long)v1[3] + (long)v2[3]) / 2 );
-
-	__asm {
-		mov			ecx, dword ptr pVects
-		mov			eax, dword ptr v1
-		mov			ebx, dword ptr v2
-
-		movd		mm0, [eax]
-		movd		mm1, [ebx]
-		pxor		mm2, mm2
-		nop
-
-		movd		[ecx], mm0
-		movd		[ecx+8], mm1
-
-		punpcklbw	mm0, mm2
-		punpcklbw	mm1, mm2
-
-		paddw		mm0, mm1
-		psrlw		mm0, 1
-
-		packuswb	mm0, mm0
-		movd		[ecx+4], mm0
-	}
-	// *(long *)&pVects[1] = r1;
-}
-
-__int64 ScaleOneThird = 0x5500550055005500;
-
-// ----------------------------------------------------------------------------
-// Build palette for a 4 color block
-// ----------------------------------------------------------------------------
-void DXTCGen::BuildCodes4(cbVector *pVects, cbVector &v1, cbVector &v2)
-{
-// 	pVects[0] = v1;
-// 	pVects[3] = v2;
-// 
-// 	pVects[1][0] = v1[0];
-// 	pVects[1][1] = (BYTE)( ((long)v1[1] * 2 + (long)v2[1]) / 3 );
-// 	pVects[1][2] = (BYTE)( ((long)v1[2] * 2 + (long)v2[2]) / 3 );
-// 	pVects[1][3] = (BYTE)( ((long)v1[3] * 2 + (long)v2[3]) / 3 );
-// 
-// 	pVects[2][0] = v1[0];
-// 	pVects[2][1] = (BYTE)( ((long)v2[1] * 2 + (long)v1[1]) / 3 );
-// 	pVects[2][2] = (BYTE)( ((long)v2[2] * 2 + (long)v1[2]) / 3 );
-// 	pVects[2][3] = (BYTE)( ((long)v2[3] * 2 + (long)v1[3]) / 3 );
-
-	__asm {
-		mov			ecx, dword ptr pVects
-		mov			eax, dword ptr v1
-		mov			ebx, dword ptr v2
-
-		movd		mm0, [eax]
-		movd		mm1, [ebx]
-
-		pxor		mm2, mm2
-		movd		[ecx], mm0
-		movd		[ecx+12], mm1
-
-		punpcklbw	mm0, mm2
-		punpcklbw	mm1, mm2
-		movq		mm3, mm0		// mm3 = v0
-
-		paddw		mm0, mm1		// mm0 = v0 + v1
-		paddw		mm3, mm3		// mm3 = v0*2
-
-		paddw		mm0, mm1		// mm0 = v0 + v1*2
-		paddw		mm1, mm3		// mm1 = v0*2 + v1
-
-		pmulhw		mm0, ScaleOneThird
-		pmulhw		mm1, ScaleOneThird
-		packuswb	mm1, mm0
-
-		movq		[ecx+4], mm1
-	}
-}
-*/
-
 void BlockDXT1::decodeBlock(ColorBlock * block) const
 {
 	nvDebugCheck(block != NULL);
diff --git a/src/nvimage/BlockDXT.h b/src/nvimage/BlockDXT.h
index 5a45c40..6510e96 100644
--- a/src/nvimage/BlockDXT.h
+++ b/src/nvimage/BlockDXT.h
@@ -47,7 +47,8 @@ namespace nv
 		bool isFourColorMode() const;
 	
 		uint evaluatePalette(Color32 color_array[4]) const;
-		uint evaluatePaletteFast(Color32 color_array[4]) const;
+		uint evaluatePaletteNV5x(Color32 color_array[4]) const;
+
 		void evaluatePalette3(Color32 color_array[4]) const;
 		void evaluatePalette4(Color32 color_array[4]) const;