From 28994509cc11ac6a5443054dfae1fedfb69039bc Mon Sep 17 00:00:00 2001
From: rsc <devnull@localhost>
Date: Wed, 21 Apr 2004 22:19:33 +0000
Subject: Why not?

---
 src/cmd/jpg/rgbycc.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 src/cmd/jpg/rgbycc.c

(limited to 'src/cmd/jpg/rgbycc.c')

diff --git a/src/cmd/jpg/rgbycc.c b/src/cmd/jpg/rgbycc.c
new file mode 100644
index 00000000..3654a2d2
--- /dev/null
+++ b/src/cmd/jpg/rgbycc.c
@@ -0,0 +1,120 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+
+float c1 = 1.402;
+float c2 = 0.34414;
+float c3 = 0.71414;
+float c4 = 1.772;
+
+int
+closest(int Y, int Cb, int Cr)
+{
+	double r, g, b;
+	double diff, min;
+	int rgb, R, G, B, v, i;
+	int y1, cb1, cr1;
+
+	Cb -= 128;
+	Cr -= 128;
+	r = Y+c1*Cr;
+	g = Y-c2*Cb-c3*Cr;
+	b = Y+c4*Cb;
+
+//print("YCbCr: %d %d %d, RGB: %g %g %g\n", Y, Cb, Cr, r, g, b);
+
+	min = 1000000.;
+	v = 1000;
+	for(i=0; i<256; i++){
+		rgb =  cmap2rgb(i);
+		R = (rgb >> 16) & 0xFF;
+		G = (rgb >> 8) & 0xFF;
+		B = (rgb >> 0) & 0xFF;
+		diff = (R-r)*(R-r) + (G-g)*(G-g) + (B-b)*(B-b);
+		y1 = 0.5870*G + 0.114*B + 0.299*R;
+		cb1 = (B-y1)/1.772;
+		cr1 = (R-y1)/1.402;
+		if(diff < min){
+//			if(Y==0 && y1!=0)
+//				continue;
+			if(Y==256-16 && y1<256-16)
+				continue;
+//			if(Cb==0 && cb1!=0)
+//				continue;
+			if(Cb==256-16 && cb1<256-16)
+				continue;
+//			if(Cr==0 && cr1!=0)
+//				continue;
+			if(Cr==256-16 && cr1<256-16)
+				continue;
+//print("%d %d %d\n", R, G, B);
+			min = diff;
+			v = i;
+		}
+	}
+	if(v > 255)
+		abort();
+	return v;
+}
+
+void
+main(int argc, char *argv[])
+{
+	int i, rgb;
+	int r, g, b;
+	double Y, Cr, Cb;
+	int y, cb, cr;
+	uchar close[16*16*16];
+
+//print("%d\n", closest(atoi(argv[1]), atoi(argv[2]), atoi(argv[3])));
+//exits("X");
+
+	/* ycbcrmap */
+	print("uint ycbcrmap[256] = {\n");
+	for(i=0; i<256; i++){
+		if(i%8 == 0)
+			print("\t");
+		rgb = cmap2rgb(i);
+		r = (rgb>>16) & 0xFF;
+		g = (rgb>>8) & 0xFF;
+		b = (rgb>>0) & 0xFF;
+		Y = 0.5870*g + 0.114*b + 0.299*r;
+		Cr = (r-Y)/1.402 + 128.;
+		Cb = (b-Y)/1.772 + 128.;
+		if(Y<0. || Y>=256. || Cr<0. || Cr>=256. || Cb<0. || Cb>=256.)
+			print("bad at %d: %d %d %d; %g %g %g\n", i, r, g, b, Y, Cb, Cr);
+		r = Y;
+		g = Cb;
+		b = Cr;
+		print("0x%.6ulX, ", (r<<16) | (g<<8) | b);
+		if(i%8 == 7)
+			print("\n");
+	}
+	print("};\n\n");
+
+	/* closestycbcr */
+	print("uchar closestycbcr[16*16*16] = {\n");
+	for(y=0; y<256; y+=16)
+	for(cb=0; cb<256; cb+=16)
+	for(cr=0; cr<256; cr+=16)
+		close[(cr/16)+16*((cb/16)+16*(y/16))] = closest(y, cb, cr);
+if(0){
+	/*weird: set white for nearly white */
+	for(cb=128-32; cb<=128+32; cb+=16)
+	for(cr=128-32; cr<=128+32; cr+=16)
+		close[(cr/16)+16*((cb/16)+16*(255/16))] = 0;
+	/*weird: set black for nearly black */
+	for(cb=128-32; cb<=128+32; cb+=16)
+	for(cr=128-32; cr<=128+32; cr+=16)
+		close[(cr/16)+16*((cb/16)+16*(0/16))] = 255;
+}
+	for(i=0; i<16*16*16; i++){
+		if(i%16 == 0)
+			print("\t");
+		print("%d,", close[i]);
+		if(i%16 == 15)
+			print("\n");
+	}
+	print("};\n\n");
+	exits(nil);
+}
-- 
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