maorduino/tools/gimp_img_conv/gimp_img_conv.c

#define SIZE 120
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <stdbool.h>
#include "glib.h"
#include "base_image.c"

int color_u8_to_u6(int v) {
    const double conversion_ratio = 63.0 / 255.0;
    return (int)(v * conversion_ratio);  
}

int color_u8_to_u5(int v) {
    const double conversion_ratio = 31.0 / 255.0;
    return (int)(v * conversion_ratio);  
}

void main() {
    printf("static const unsigned short gimp_image[%d] = {", gimp_image.width * gimp_image.height);
    bool include_comma = false;
    for (int x = 0; x < gimp_image.width; x++) {
        for (int y = 0; y < gimp_image.height; y++) {
            int idx = 3 * (y * gimp_image.width + x);
            // for some reason
            // red = 5 bytes
            // green = 6 bytes
            // blue = 5 bytes
            int r = (int)gimp_image.pixel_data[idx] & 0xFF;
            int g = (int)gimp_image.pixel_data[idx + 1] & 0xFF;
            int b = (int)gimp_image.pixel_data[idx + 2] & 0xFF;
            uint16_t color = (color_u8_to_u5(r) << 11) | (color_u8_to_u6(g) << 5) | color_u8_to_u5(b);
            if (!include_comma) {
                include_comma = true;
            } else {
                printf(", ");
            }
            printf("0x%X", color);
        }
    }
    printf("};\n");
}