From 39ed87570bdb2f86969d4be821c94b722dc71179 Mon Sep 17 00:00:00 2001
From: Joe Ludwig <joe@valvesoftware.com>
Date: Wed, 26 Jun 2013 15:22:04 -0700
Subject: First version of the SOurce SDK 2013

---
 mp/src/mathlib/imagequant.cpp | 96 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 mp/src/mathlib/imagequant.cpp

(limited to 'mp/src/mathlib/imagequant.cpp')

diff --git a/mp/src/mathlib/imagequant.cpp b/mp/src/mathlib/imagequant.cpp
new file mode 100644
index 00000000..fddafa74
--- /dev/null
+++ b/mp/src/mathlib/imagequant.cpp
@@ -0,0 +1,96 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//
+//=============================================================================//
+#include <quantize.h>
+#include <minmax.h>
+
+#define N_EXTRAVALUES 1
+#define N_DIMENSIONS (3+N_EXTRAVALUES)
+
+#define PIXEL(x,y,c) Image[4*((x)+((Width*(y))))+c]
+
+static uint8 Weights[]={5,7,4,8};
+static int ExtraValueXForms[3*N_EXTRAVALUES]={
+	76,151,28,
+};
+
+  
+
+#define MAX_QUANTIZE_IMAGE_WIDTH 4096
+
+void ColorQuantize(uint8 const *Image,
+				   int Width,
+				   int Height,
+				   int flags, int ncolors,
+				   uint8 *out_pixels,
+				   uint8 *out_palette,
+				   int firstcolor)
+{
+	int Error[MAX_QUANTIZE_IMAGE_WIDTH+1][3][2];
+	struct Sample *s=AllocSamples(Width*Height,N_DIMENSIONS);
+	int x,y,c;
+	for(y=0;y<Height;y++)
+		for(x=0;x<Width;x++)
+		{
+			for(c=0;c<3;c++)
+				NthSample(s,y*Width+x,N_DIMENSIONS)->Value[c]=PIXEL(x,y,c);
+			// now, let's generate extra values to quantize on
+			for(int i=0;i<N_EXTRAVALUES;i++)
+			{
+				int val1=0;
+				for(c=0;c<3;c++)
+					val1+=PIXEL(x,y,c)*ExtraValueXForms[i*3+c];
+				val1>>=8;
+				NthSample(s,y*Width+x,N_DIMENSIONS)->Value[c]=(uint8)
+					(min(255,max(0,val1)));
+			}
+		}
+	struct QuantizedValue *q=Quantize(s,Width*Height,N_DIMENSIONS,
+									  ncolors,Weights,firstcolor);
+	delete[] s;
+	memset(out_palette,0x55,768);
+	for(int p=0;p<256;p++)
+	{
+		struct QuantizedValue *v=FindQNode(q,p);
+		if (v)
+			for(int c=0;c<3;c++)
+				out_palette[p*3+c]=v->Mean[c];
+	}
+	memset(Error,0,sizeof(Error));
+	for(y=0;y<Height;y++)
+	{
+		int ErrorUse=y & 1;
+		int ErrorUpdate=ErrorUse^1;
+		for(x=0;x<Width;x++)
+		{
+			uint8 samp[3];
+			for(c=0;c<3;c++)
+			{
+				int tryc=PIXEL(x,y,c);
+				if (! (flags & QUANTFLAGS_NODITHER))
+				{
+					tryc+=Error[x][c][ErrorUse];
+					Error[x][c][ErrorUse]=0;
+				}
+				samp[c]=(uint8) min(255,max(0,tryc));
+			}
+			struct QuantizedValue *f=FindMatch(samp,3,Weights,q);
+			out_pixels[Width*y+x]=(uint8) (f->value);
+			if (! (flags & QUANTFLAGS_NODITHER))
+				for(int i=0;i<3;i++)
+				{
+					int newerr=samp[i]-f->Mean[i];
+					int orthog_error=(newerr*3)/8;
+					Error[x+1][i][ErrorUse]+=orthog_error;
+					Error[x][i][ErrorUpdate]=orthog_error;
+					Error[x+1][i][ErrorUpdate]=newerr-2*orthog_error;
+				}
+		}
+	}
+	if (q) FreeQuantization(q);
+}
+
-- 
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