gistfile1.cpp

// sillycocg.cpp : disgusting test code. loads a 320x180 rgb image from input.raw
// writes out a (fixed) photoshop-style 3 bytes per index palette file to ycocg.act
// you can load this in photoshop via image/mode/index then image/mode/color-table.../load...
// then it writes out an 8bpp indexed image to output.raw
// its kinda a hindsight is 2020 thing, the old 'fake truecolor' demos that did RGB stripes/
// patterns - I wondered what it would be like to do something like
// http://www.pmavridis.com/research/fbcompression/
// but 15 years ago in 256 color mode, so you compute 2 channels per pixel instead of 3,
// and those channels are Y and one of Co or Cg; then you alternate Co/Cg in a checkerboard
// and pack 4 bits y, 3 bits chroma, 1 bit checkerboard switch. 
// it's kinda meh, but if I'd thought of it 15 years ago, I would definitely have made a 
// cool demo with it. alas, I'm a bit late :)
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
typedef unsigned char u8;
int clamp(int i) { if (i<0) return 0; if (i>255) return 255; return i; }
int _tmain(int argc, _TCHAR* argv[])
{
	u8 input[180][320][3];
	FILE *f=fopen("c:/input.raw","rb");
	fread(input,320,180*3,f);
	fclose(f);	
	f=fopen("c:/ycocg.act","wb");
	for (int y=0;y<16;++y) 
	for (int c=0;c<8;++c) 
	for (int p=0;p<2;++p)	{
		int Cg = p ? 0 : (c*32+16-128),Co = p ? (c*32+16-128) : 0,Y=y*16+8;
		int R=clamp(Y + Co-Cg),G=clamp(Y + Cg),B=clamp(Y - Co-Cg);		
		fwrite(&R,1,1,f);		fwrite(&G,1,1,f);		fwrite(&B,1,1,f);
	}
	fclose(f);
	f=fopen("c:/output.raw","wb");
	for (int y=0;y<20;++y)
	for (int x=0;x<320;++x) 	{
		int i=x; if (i>255) i=0;if (y>10) i=0;fwrite(&i,1,1,f);
	}
	for (int y=0;y<180;++y)
	for (int x=0;x<320;++x) 	{
		int R=input[y][x][0],G=input[y][x][1],B=input[y][x][2];
		int Y=int(0.5+0.25*R+0.5*G+0.25*B),Co=int(0.5+0.5*R-0.5*B),Cg=int(0.5+-0.25*R+0.5*G-0.25*B);
		Co*=2;	Cg*=2;
		Y=clamp(Y+(rand()&15))/16;
		Co=clamp(Co+128+(rand()&31))/32;
		Cg=clamp(Cg+128+(rand()&31))/32;
		int ch=(x^y)&1;
		if (!ch) Co=Cg;
		int i=(Y<<4)+(Co<<1)+ch;
		fwrite(&i,1,1,f);
	}
	fclose(f);
	return 0;
}