Mega Code Archive
Create a negative from png image
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#include <stdio.h>
#include <error.h>
#include <gd.h>
int main(int argc, char *argv[]) {
FILE *fp = {0};
gdImagePtr img;
char *iname = NULL;
char *oname = NULL;
int color, x, y, w, h;
int red, green, blue;
color = x = y = w = h = 0;
red = green = blue = 0;
if(argc != 3)
error(1, 0, "Usage: gdnegat input.png output.png");
else {
iname = argv[1];
oname = argv[2];
}
if((fp = fopen(iname, "r")) == NULL)
error(1, 0, "Error - fopen(): %s", iname);
else
img = gdImageCreateFromPng(fp);
w = gdImageSX(img);
h = gdImageSY(img);
for(x = 0; x < w; x++) {
for(y = 0; y < h; y++) {
color = gdImageGetPixel(img, x, y);
red = 255 - gdImageRed(img, color);
green = 255 - gdImageGreen(img, color);
blue = 255 - gdImageBlue(img, color);
color = gdImageColorAllocate(img, red, green, blue);
gdImageSetPixel(img, x, y, color);
}
}
if((fp = fopen(oname, "w")) == NULL)
error(1, 0, "Error - fopen(): %s", oname);
else {
gdImagePng(img, fp);
fclose(fp);
}
gdImageDestroy(img);
return 0;
}
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