public int getUniqueChars() {
        String uniques = "";

        for (int x = 0; x < getWidth(); ++x) {
            for (int y = 0; y < getHeight(); ++y) {
                char c = getPixel(x, y);
                if (!uniques.contains("" + c))
                    uniques += c;
            }
        }

        return uniques.length();
    }