PhotoToAscii.c

#define _CRT_SECURE_NO_WARNINGS /* Shut up, Visual Studio */

#include <stdio.h>
#include <stdlib.h>
#include <SOIL.h>

const char *asciichars = "#*+=-:. ";

int main(int argc, char **argv) {
	if (argc != 3) { printf("Syntax: %s <infile> <outfile>\n", argv[0]); return -1;	}

	int width, height, channels;
	unsigned char *data = SOIL_load_image(argv[1], &width, &height, &channels, 1);
	if (!data) { printf("Loading error: %s\n", SOIL_last_result()); return -1; }
	char *output = new char[(height/2 + 1) * (width+1)];

	int i = 0;
	for (int y = 0; y < height; y += 2) { /* +2 to compensate for characters being higher than they're wide */
		for (int x = 0; x < width; ++x)
			output[i++] = asciichars[data[y * width + x] >> 5];
		output[i++] = '\n';
	}

	FILE *out = fopen(argv[2], "w");
	if (!out) return -1;
	fwrite(output, 1, height/2 * (width + 1), out);
	fclose(out);

	return 0;
}