ChromakeyMan v2.1

chromakeyman2.c

/*
 * ChromakeyMan v2.1
 * by 'Bl0ckeduser'
 *
 * A simple chroma-key effect program
 * 
 * Originally written in METAL Basic
 * (on Mac OS 9) in 2007-2008 for ad-hoc 
 * use in a little VFX project.
 *
 * SDL/C port, July 2012
 *
 * getpixel() and putpixel() are from
 * Sam Lantinga's excellent SDL docs.
 *
 * Improvements being made July 2012:
 *  - local RGB tolerance
 *  - pixel adjacency check --
 *    avoid keying out regions
 *    not contiguous with already
 *    keyed-out regions
 *  - a little refactoring and commenting,
 *    but not enough
 *
 * WARNING: Never written with any serious
 * algorithms in mind. The code quality
 * is quite low as I wrote the core when
 * I was around 13 in Basic. (gotos everywhere)
 * I didn't refactor much. I write better
 * code today, I assure you. The technical terms
 * are probably wrong.
 *
 * Input: 1.bmp, 2.bmp, 3.bmp, ... in local
 *        directory
 * 
 * Output: same, if -s option is used.
 *         Otherwise, none. Keyed out
 *         region is converted to pure
 *         green pixels.
 *
 * You can use ffmpeg tricks to convert
 * to and from BMP-reel (see http://pr0gr4mm3r.com/linux/
 * convert-video-to-images-and-back-using-ffmpeg/).
 * I use:
 *  ffmpeg -i $1 -r 30 -f image2 REEL/F%d.bmp
 *  ffmpeg -i REEL/F%d.bmp -r 30 -vcodec huffyuv reel.avi
 * 
 * Use: launch program. Type in values
 *      for parameters. Click on a pixel
 *      part of region to be keyed. Watch
 *      result.
 */

#include "SDL.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel);
Uint32 getpixel(SDL_Surface *surface, int x, int y);

void plot(int x, int y);

/* 
 * Emulate the QuickDraw-style
 * graphics calls in METAL
 */
void forecolor(int r, int g, int b);
void get_pixel(int x, int y, int* r, int* g, int* b);
int forecolor_r,
    forecolor_g,
    forecolor_b;

SDL_Surface *screen;

int xl, yl;

void fail(char *s) {
	fprintf(stderr, "failure: %s\n", s);
	exit(1);
}

int main(int argc, char** argv)
{
	int dif = 17000; /* POWER : dif */
	int areatol;
	int lvalid = 0;
	int privater, privateg, privateb;
	int fid;
	int ex, ey;
	char buf[1024];
	int mx, my;
	int r, g, b;
	int rmn = 0, rmp = 0;
	int gmn = 0, gmp = 0;
	int bmn = 0, bmp = 0;
	int rcolr, rcolg, rcolb;
	int nr, ng, nb;
	int off = 0;

	/* local tolerance */
	int localtol;
	int pr, pg, pb;
	int chk;
	
	/* pixel adjacency matrix */
	int** matrix;
	int i, j;
	int kc;
	int achk;

	SDL_Surface *image;
	SDL_Event event;
	const SDL_VideoInfo *info;
	int sflag = 0;

	while(argc--)
		if(!strcmp(*argv++, "-s")) {
			printf("save mode\n");
			sflag = 1;
		}

	printf("ChromakeyMan 2.1\n");
	printf("by 'Bl0ckeduser', 2007, 2008, 2012\n\n");
	printf("Chromakey detection POWER (17000): ");	scanf("%d", &dif);
	printf("Chromakey FILL TOLERANCE (15): "); scanf("%d", &areatol);
	printf("Local color tolerance (3000): "); scanf("%d", &localtol);

	/*
	 * Setup SDL video
	 */
	if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTTHREAD) != 0)
		fail("SDL initialization");

	image = SDL_LoadBMP("F2.bmp");
	if(!image)
		fail("F2.bmp");
	xl = image->w;
	yl = image->h;

	/*
	 * Allocate adjacency matrix
	 */
	matrix = malloc((yl+1) * sizeof(int **));
	if(!matrix) fail("malloc matrix");
	for(i = 0; i <= yl; i++)
	{
		matrix[i] = malloc((xl + 1) * sizeof(int *));
		if(!matrix[i]) fail("malloc matrix[i]");
	}

	/*
	 * Setup SDL screen
	 */
	if(!(info = SDL_GetVideoInfo()))
		fail("video info");
	if(!(screen = SDL_SetVideoMode(xl, yl, info->vfmt->BitsPerPixel, SDL_DOUBLEBUF)))
		fail("Screen creation");

	/* Fill screen with white */
	SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 255, 255, 255));

	/* Draw the initial frame */
	SDL_BlitSurface(image, NULL, screen, NULL);
	SDL_Flip(screen);

	/*
	 * Wait for the user to click on a
	 * pixel part of the region to be
	 * keyed out.
	 */
	do
		SDL_WaitEvent(&event);
	while(event.type != SDL_MOUSEBUTTONDOWN);
	mx = event.button.x;
	my = event.button.y;

	get_pixel(mx, my, &r, &g, &b);

	privater=round(r/257.0f)*257;
	privateg=round(g/257.0f)*257;
	privateb=round(b/257.0f)*257;

	fid=3;
	xl=xl-1;
	yl=yl-1;


	CONSTANT :
	ex=0;	
	ey=0;

	/*
	 * Load a new frame if possible,
	 * otherwise stop.
	 */
	SDL_FreeSurface(image);
	sprintf(buf, "F%d.bmp", fid);
	if ((image = SDL_LoadBMP(buf))) {
		SDL_BlitSurface(image, NULL, screen, NULL);
	} else {
		goto end;
	}

	/*
	 * Set up a blank adjacency matrix
	 * for this frame.
	 */
	for(i = 0; i <= yl; i++)
		for(j = 0; j <= xl; j++)
			matrix[i][j] = 0;
	kc = 0;


	/* Moyenne de couleur (color average) */

	watr:

	/* RED */

	if (r>65534) {
		rmn=r-dif;
		rmp=0;
	} else {
		if (r<1) {
			rmn=2000;
			rmp=r+dif;
		} else {
			rmn=r-dif;
			rmp=r+dif;
		}
	}
	
	/* GREEN */
	
	if (g>65534) {
		gmn=g-dif;
		gmp=0;
	} else {
		if (g<1) {
			gmn=2000;
			gmp=g+dif;
		} else {
			gmn=g-dif;
			gmp=g+dif;
		}
	}
	

	/* BLUE */
	
	if (b>65534) {
		bmn=b-dif;
		bmp=0;
	} else {
		if (b<1) {
			bmn=2000;
			bmp=b+dif;
		} else {
			bmn=b-dif;
			bmp=b+dif;	
		}
	}
	
	POSTER :
	
	rcolr=65535;
	rcolg=65535;
	rcolb=65535;
	
	get_pixel(ex, ey, &nr, &ng, &nb);

	if(chk++) {
		/* 
		 * Check local RGB tolerance against
		 * left pixel
		 */
		if(abs(pr-nr) + abs(pg-ng) + abs(pb-nb) > localtol) {
			ng = gmn-1; /* hack to choke test below */
		}
	}
	pr = nr;
	pg = ng;
	pb = nb;

	if(kc >= 5) {
		/*
		 * Check for adjacent keyed-in
		 * pixel
		 */
		achk = 0;

		if(ex > 0)
			if(matrix[ey][ex - 1])
				achk = 1;
		if(ey > 0)
			if(matrix[ey - 1][ex])
				achk = 1;

		if(ex > 0 && ey > 0)
			if(matrix[ey - 1][ex - 1])
				achk = 1;

		if(!achk)
			ng = gmn-1; /* hack to choke test below */	
	}

	/* Reds posterize */
	if (nr<rmp && nr>rmn && nb<bmp && nb>bmn && ng<gmp && ng>gmn) {
		if (abs(ex-lvalid) < areatol) {
			if(ex <= xl && ey <= yl)
				matrix[ey][ex] = 1;
			kc++;
			forecolor(0, 65535, 0);
			plot(ex, ey);
			lvalid=ex;
			rcolr=0;
			rcolg=0;
			rcolb=0;
		}
	}
	
	ex=ex+1;

	/*
	 * If we made it to the end of the
	 * line, do it again backwards
	 */
	if (ex>xl) {
		lvalid=xl;
	
		/* --- double pass ... ---*/

		chk = 0;
		do {
			rcolr=65535;
			rcolg=65535;
			rcolb=65535;
	
			get_pixel(ex, ey, &nr, &ng, &nb);

			if(chk++) {
				get_pixel(ex - 1, ey, &pr, &pg, &pb);
				if(abs(pr-nr) + abs(pg-ng) + abs(pb-nb) > localtol) {
					ng = gmn-1; /* hack to choke test below */
				}
			}
			pr = nr;
			pg = ng;
			pb = nb;

			if(kc >= 5) {
				/*
				 * Check for adjacent keyed-in
				 * pixel, but backwards, since
				 * this pass goes backwards.
				 */
				achk = 0;

				if(ex < xl - 1)
					if(matrix[ey][ex + 1])
						achk = 1;
				if(ey < yl - 1)
					if(matrix[ey + 1][ex])
						achk = 1;

				if(ex < xl - 1 && ey < yl - 1)
					if(matrix[ey + 1][ex + 1])
						achk = 1;

				/*
				 * Also check forwards.
				 */
				if(ex > 0)
					if(matrix[ey][ex - 1])
						achk = 1;
				if(ey > 0)
					if(matrix[ey - 1][ex])
						achk = 1;

				if(ex > 0 && ey > 0)
					if(matrix[ey - 1][ex - 1])
						achk = 1;


				if(!achk)
					ng = gmn-1; /* hack to choke test below */	
			}

			/* Reds posterize */
			if (nr<rmp && nr>rmn && nb<bmp && nb>bmn && ng<gmp && ng>gmn) {
				if (abs(ex-lvalid)<areatol) {
					forecolor(0, 65535, 0);
					plot(ex,ey);
					lvalid=ex;
					if(ex <= xl && ey <= yl)
						matrix[ey][ex] = 1;
					kc++;
					rcolr=0;
					rcolg=0;
					rcolb=0;
				}
			}
			ex=ex-1;
		}
		while(ex > 1);

		/* --- double pass ... ---*/
	
		lvalid=0;
		ey=ey+1;
		chk = 0;
	}

	if (ey>yl) {
		goto ENDR;
	}

	goto watr;

	/*
	 * Save the chromakeyed frame
	 * and jump to the code that
	 * checks for a next frame.
	 */
	ENDR :
	SDL_Flip(screen);
	if(sflag) {
		sprintf(buf, "F%d.bmp", fid);
		remove(buf);
		if(SDL_SaveBMP(screen, buf))
			fail("save bmp");
	}
	fid=fid+1;
	goto CONSTANT;


	end:

	/*
	 * Clean up SDL stuff
	 */
	SDL_Quit();
	SDL_FreeSurface(image);

	return 0;
}

/* 
 * putpixel() and getpixel() are taken from
 * examples in the SDL documentation, written
 * by the SDL author, Sam Lantinga.
 */
	
/*
 * Set the pixel at (x, y) to the given value
 * NOTE: The surface must be locked before calling this!
 */
void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel)
{
    int bpp = surface->format->BytesPerPixel;
    /* Here p is the address to the pixel we want to set */
    Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;

    switch(bpp) {
    case 1:
        *p = pixel;
        break;

    case 2:
        *(Uint16 *)p = pixel;
        break;

    case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {
            p[0] = (pixel >> 16) & 0xff;
            p[1] = (pixel >> 8) & 0xff;
            p[2] = pixel & 0xff;
        } else {
            p[0] = pixel & 0xff;
            p[1] = (pixel >> 8) & 0xff;
            p[2] = (pixel >> 16) & 0xff;
        }
        break;

    case 4:
        *(Uint32 *)p = pixel;
        break;
    }
}

/*
 * Return the pixel value at (x, y)
 * NOTE: The surface must be locked before calling this!
 */
Uint32 getpixel(SDL_Surface *surface, int x, int y)
{
    int bpp = surface->format->BytesPerPixel;
    /* Here p is the address to the pixel we want to retrieve */
    Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;

    switch(bpp) {
    case 1:
        return *p;

    case 2:
        return *(Uint16 *)p;

    case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
            return p[0] << 16 | p[1] << 8 | p[2];
        else
            return p[0] | p[1] << 8 | p[2] << 16;

    case 4:
        return *(Uint32 *)p;

    default:
        return 0;       /* shouldn't happen, but avoids warnings */
    }
}

/*
 * Emulation of METAL QuickDraw graphics
 * API
 */

void plot(int x, int y)
{
	Uint32 color = SDL_MapRGB(screen->format,
		forecolor_r / 257,
		forecolor_g / 257,
		forecolor_b / 257);
	if(x > xl || y > yl)
		return;
	putpixel(screen, x, y, color);
}

void forecolor(int r, int g, int b)
{
	forecolor_r = r;
	forecolor_g = g;
	forecolor_b = b;
}

void get_pixel(int x, int y, int* r, int* g, int* b)
{
	Uint8 ur, ug, ub;
	Uint32 color;
	if(x > xl || y > yl)
		return;
	color = getpixel(screen, x, y);
	SDL_GetRGB(color, screen->format, &ur, &ug, &ub);
	/* METAL Basic uses 0-65535 RGB range */
	*r = 257 * ur;
	*g = 257 * ug;
	*b = 257 * ub;
}