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invert.c
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invert.c
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#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include "ppm.h"
// W H chan
#define MAX_IMG_SZ ( 1280 * 720 * 3 )
#define PIXIDX ((i* (*col) * (*chan))+(j* (*chan))+k)
#define SAT (255)
#define OUT_FILENAME "inverted.ppm"
// requires that newimg points to allocated memory
void invert(unsigned char *img, unsigned char *newimg, unsigned * row, unsigned * col, unsigned * chan)
{
int pix, i, j, k;
unsigned char newPix;
printf("Begin Inversion...");
for(i=0; i < *row; i++)
for(j=0; j < *col; j++)
for(k=0; k < *chan; k++)
{
newimg[PIXIDX] = SAT - img[PIXIDX];
}
printf(" done.\n");
}
int main(int argc, char *argv[])
{
char header[512];
unsigned char img[MAX_IMG_SZ], invertedimg[MAX_IMG_SZ];
int bufflen, hdrlen;
unsigned row=0, col=0, chan=0;
if(argc != 2)
{
printf("Use: invert inputfile\n");
exit(-1);
}
printf("Reading PPM\n");
header[0]='\0';
readppm(img, &bufflen, header, &hdrlen, &row, &col, &chan, argv[1]);
printf("PPM read\n");
invert(img, invertedimg, &row, &col, &chan);
printf("Writing PPM\n");
writeppm(invertedimg, bufflen, header, hdrlen, OUT_FILENAME);
printf("PPM written\n");
}