pixel* read_file(char** argv, int* xsize, int* ysize, int* colmax){
FILE* infile;
if (!(infile = fopen(argv[2], "r"))) {
fprintf(stderr, "Error when opening %s\n", argv[2]);
exit(1);
}
int magic = ppm_readmagicnumber(infile);
if (magic != 'P'*256+'6') {
fprintf(stderr, "Wrong magic number\n");
exit(1);
}
*xsize = ppm_readint(infile);
*ysize = ppm_readint(infile);
*colmax = ppm_readint(infile);
if (*colmax > 255) {
fprintf(stderr, "Too large maximum color-component value\n");
exit(1);
}
pixel* image = allocate_image((*xsize)*(*ysize));
if (!fread(image, sizeof(pixel), (*xsize)*(*ysize), infile)) {
fprintf(stderr, "error in fread\n");
exit(1);
}
return image;
}
int main(int argc, char **argv)
{
FILE *infile, *outfile;
int magic, ok;
int radius;
int xsize, ysize, colmax;
pixel *image;
int x,y;
int avg, pval, psum, sum = 0;
/* Take care of the arguments */
if (argc != 3) {
fprintf(stderr, "Usage: %s infile outfile\n", argv[0]);
exit(2);
}
if (!(infile = fopen(argv[1], "r"))) {
fprintf(stderr, "Error when opening %s\n", argv[1]);
exit(1);
}
if (!(outfile = fopen(argv[2], "w"))) {
fprintf(stderr, "Error when opening %s\n", argv[2]);
exit(1);
}
/* read file */
magic = ppm_readmagicnumber(infile);
if (magic != 'P'*256+'6') {
fprintf(stderr, "Wrong magic number\n");
exit(1);
}
xsize = ppm_readint(infile);
ysize = ppm_readint(infile);
colmax = ppm_readint(infile);
if (colmax > 255) {
fprintf(stderr, "Too large maximum color-component value\n");
exit(1);
}
image = allocate_image(xsize*ysize);
if (!fread(image, sizeof(pixel), xsize*ysize, infile)) {
fprintf(stderr, "error in fread\n");
exit(1);
}
/* filter */
for (y=0; y<ysize; y++) {
for (x=0; x<xsize; x++) {
sum += PIXEL(image,x,y)->r;
sum += PIXEL(image,x,y)->g;
sum += PIXEL(image,x,y)->b;
}
}
avg = sum/(xsize*ysize);
for (y=0; y<ysize; y++) {
for (x=0; x<xsize; x++) {
psum = PIXEL(image,x,y)->r;
psum += PIXEL(image,x,y)->g;
psum += PIXEL(image,x,y)->b;
if (psum > avg)
pval = colmax;
else
pval = 0;
PIXEL(image,x,y)->r = pval;
PIXEL(image,x,y)->g = pval;
PIXEL(image,x,y)->b = pval;
}
}
/* write result */
fprintf(outfile, "P6 %d %d %d\n", xsize, ysize, colmax);
if (!fwrite(image, sizeof(pixel), xsize*ysize, outfile)) {
fprintf(stderr, "error in fwrite");
exit(1);
}
exit(0);
}
/* Read PPM file */
unsigned char* ppm_read(FILE* file,int& cols,int& rows){
unsigned char* pixels,*pix;
unsigned int r,g,b;
int format,maxval;
int row,col;
/* Get format */
format=ppm_readmagicnumber(file);
/* Get size */
cols=ppm_getint(file);
rows=ppm_getint(file);
maxval=ppm_getint(file);
if(maxval<=0 || maxval>1023){
fprintf(stderr,"Illegal maxval value: %d.\n",maxval);
exit(1);
}
/* Create memory */
pixels=(unsigned char*)malloc(3*rows*cols);
if(!pixels){
fprintf(stderr,"Image too big\n");
exit(1);
}
/* Load pixels */
pix=pixels;
switch(format){
case PPM_FORMAT:
for(row=0; row<rows; row++){
for(col=0; col<cols; col++){
r = (255*ppm_getint(file))/maxval;
g = (255*ppm_getint(file))/maxval;
b = (255*ppm_getint(file))/maxval;
*pix++ = r;
*pix++ = g;
*pix++ = b;
}
}
break;
case RPPM_FORMAT:
for(row=0; row<rows; row++){
for(col=0; col<cols; col++){
r = ppm_getrawbyte(file);
g = ppm_getrawbyte(file);
b = ppm_getrawbyte(file);
*pix++ = r;
*pix++ = g;
*pix++ = b;
}
}
break;
default:
fprintf(stderr,"Unknown format.\n");
exit(1);
break;
}
return pixels;
}
