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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "ppm.h"
static Image image_convolution(Image input, float kernel[9]);
static void split_rgb(Image input, uint8_t *r, uint8_t *g, uint8_t *b);
static void merge_rgb(Image *out, uint8_t *r, uint8_t *g, uint8_t *b);
static uint8_t kernel_op(uint8_t *data, float kernel[9], int i, int j, int w, int h);
Image
image_convolution(Image input, float kernel[9])
{
Image out;
out.width = input.width;
out.height = input.height;
out.pixel_bits = input.pixel_bits;
size_t n_pixels = out.width * out.height * 3;
out.data = calloc(n_pixels, sizeof(uint8_t));
if (out.data == NULL) {
perror("image_convolution() Error");
exit(1);
}
uint8_t *r, *g, *b;
r = calloc(input.width * input.height, sizeof(uint8_t));
g = calloc(input.width * input.height, sizeof(uint8_t));
b = calloc(input.width * input.height, sizeof(uint8_t));
split_rgb(input, r, g, b);
int i, j, index;
for (i = 0; i < input.height; i++) {
for (j = 0; j < input.width; j++) {
index = i * input.width + j;
r[index] = kernel_op(r, kernel, i, j, input.width, input.height);
g[index] = kernel_op(g, kernel, i, j, input.width, input.height);
b[index] = kernel_op(b, kernel, i, j, input.width, input.height);
}
}
merge_rgb(&out, r, g, b);
free(r);
free(g);
free(b);
return out;
}
void
merge_rgb(Image *out, uint8_t *r, uint8_t *g, uint8_t *b)
{
int i;
for (i = 0; i < out->width * out->height; i++) {
out->data[3 * i] = r[i];
out->data[3 * i + 1] = g[i];
out->data[3 * i + 2] = b[i];
}
}
uint8_t
kernel_op(uint8_t *data, float kernel[9], int i, int j, int w, int h)
{
float kernel_value = 0;
int ki, kj, img_index, index_i, index_j, index_k;
for (ki = 0; ki < 3; ki++) {
for (kj = 0; kj < 3; kj++) {
index_i = i + ki - 1; //height
index_j = j + kj - 1; //width
index_k = 3 * ki + kj;
if (index_i < 0
|| index_i >= h
|| index_j < 0
|| index_j >= w)
kernel_value += data[i * w + j] * kernel[index_k];
else {
img_index = index_i * w + index_j;
kernel_value += data[img_index] * kernel[index_k];
}
kernel_value = (kernel_value > 255) ? 255: kernel_value;
kernel_value = (kernel_value < 0) ? 0: kernel_value;
}
}
return (uint8_t)kernel_value;
}
void
split_rgb(Image input, uint8_t *r, uint8_t *g, uint8_t *b)
{
if (!r || !g || !b) {
perror("rgb_split() Error");
exit(1);
}
int i;
for (i = 0; i < input.width * input.height; i++) {
r[i] = input.data[3 * i];
g[i] = input.data[3 * i + 1];
b[i] = input.data[3 * i + 2];
}
}
int main(int argc, char *argv[])
{
Image img;
float kernel[9] = {
-1, -1, -1,
-1, 8, -1,
-1, -1, -1,
};
//for (int i = 0; i < 9; i++) kernel[i] /= 16;
ppm_read("images/synth_1.ppm", &img);
Image out_img = image_convolution(img, kernel);
ppm_write("out.ppm", &out_img);
return 0;
}
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