public void sprite_posterize(int i) {
        int len = sprite_width[i] * sprite_height[i];
        int pixels[] = sprite_pixels[i];
        int rgb332_idx[] = new int[32768];
        for (int ptr = 0; ptr < len; ptr++) {
            int l = pixels[ptr];
            rgb332_idx[((l & 0xf80000) >> 9) + ((l & 0xf800) >> 6) + ((l & 0xf8) >> 3)]++;
        }

        int palette[] = new int[256];
        palette[0] = 0xff00ff;
        int freq[] = new int[256];
        for (int col = 0; col < 32768; col++) {
            int use = rgb332_idx[col];
            if (use > freq[255]) {
                for (int k1 = 1; k1 < 256; k1++) {
                    if (use <= freq[k1])
                        continue;
                    for (int i2 = 255; i2 > k1; i2--) {
                        palette[i2] = palette[i2 - 1];
                        freq[i2] = freq[i2 - 1];
                    }

                    palette[k1] = ((col & 0x7c00) << 9) + ((col & 0x3e0) << 6) + ((col & 0x1f) << 3) + 0x40404;
                    freq[k1] = use;
                    break;
                }

            }
            rgb332_idx[col] = -1;
        }

        byte raster[] = new byte[len];
        for (int l1 = 0; l1 < len; l1++) {
            int pix = pixels[l1];
            int pix332 = ((pix & 0xf80000) >> 9) + ((pix & 0xf800) >> 6) + ((pix & 0xf8) >> 3);
            int new_pix = rgb332_idx[pix332];
            if (new_pix == -1) {
                int min_dist = 0x3b9ac9ff;
                int r = pix >> 16 & 0xff;
                int g = pix >> 8 & 0xff;
                int b = pix & 0xff;
                for (int ptr = 0; ptr < 256; ptr++) {
                    int _pix = palette[ptr];
                    int _r = _pix >> 16 & 0xff;
                    int _g = _pix >> 8 & 0xff;
                    int _b = _pix & 0xff;
                    int dist = (r - _r) * (r - _r) + (g - _g) * (g - _g) + (b - _b) * (b - _b);
                    if (dist < min_dist) {
                        min_dist = dist;
                        new_pix = ptr;
                    }
                }

                rgb332_idx[pix332] = new_pix;
            }
            raster[l1] = (byte) new_pix;
        }

        sprite_raster[i] = raster;
        sprite_palette[i] = palette;
        sprite_pixels[i] = null;
    }