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// source: https://github.com/LegUpComputing/legup-examples/tree/master/tutorials/sobel
#include <stdio.h>
#include <stdlib.h>
#include "input.h"
#include "output.h"
#define WIDTH 512
#define HEIGHT 512
void sobel_filter(unsigned char input[][WIDTH],
unsigned char output[][WIDTH]) {
int i, j;
int m, n;
int gx_sum, gy_sum, sum;
int gx[3][3] = {{-1, 0, 1},
{-2, 0, 2},
{-1, 0, 1}};
int gy[3][3] = {{ 1, 2, 1},
{ 0, 0, 0},
{-1, -2, -1}};
for (i = 0; i < HEIGHT; i++) {
for (j = 0; j < WIDTH; j++) {
sum = 0;
int outofbounds = 0;
outofbounds |= (i < 1) | (i > (HEIGHT - 2));
outofbounds |= (j < 1) | (j > (WIDTH - 2));
gx_sum = 0;
gy_sum = 0;
for (m = -1; m <= 1; m++) {
for (n = -1; n <= 1; n++) {
gx_sum += (outofbounds) ? 0 :
((int)input[i + m][j + n]) * gx[m + 1][n + 1];
gy_sum += (outofbounds) ? 0 :
((int)input[i + m][j + n]) * gy[m + 1][n + 1];
}
}
gx_sum = (gx_sum < 0) ? -gx_sum : gx_sum;
gy_sum = (gy_sum < 0) ? -gy_sum : gy_sum;
sum = gx_sum + gy_sum;
sum = (sum > 255) ? 255 : sum;
output[i][j] = (unsigned int)sum;
}
}
}
int main()
{
unsigned char sobel_output[HEIGHT][WIDTH];
sobel_filter(elaine_512_input, sobel_output);
int result = 0;
int i, j;
for(i = 0; i < HEIGHT; i++) {
for(j = 0; j < WIDTH; j++){
if( sobel_output[i][j] != elaine_512_golden_output[i][j])
result++;
}
}
if (!result)
printf("PASS!\n");
else
printf("FAIL with %d differences\n", result);
return result;
}
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