Color equalization

gistfile1.txt

// color equalization fuuu
int colors = 16;
byte[] r = new byte[colors];
byte[] g = new byte[colors];
byte[] b = new byte[colors];
for (int i = 0; i < colors; i++) {
 r[i] = (byte) (i*256/colors & 0xFF);
 g[i] = (byte) (i*256/colors & 0xFF);
 b[i] = (byte) (i*256/colors & 0xFF);
}

    public static byte[] toPng(Image imagen, int newHeight){

        BufferedImage bufferedImage = (BufferedImage) imagen;
        float quality = 0.9f;
        int newWidth = obtenerAnchoProporcional(bufferedImage, newHeight);

        // color equalization fuuu
        int colors = 16;
        byte[] r = new byte[colors];
        byte[] g = new byte[colors];
        byte[] b = new byte[colors];
        for (int i = 0; i < colors; i++) {
            r[i] = (byte) (i*256/colors & 0xFF);
            g[i] = (byte) (i*256/colors & 0xFF);
            b[i] = (byte) (i*256/colors & 0xFF);
        }
        IndexColorModel cm = new IndexColorModel(4, colors, r, g, b);
        BufferedImage rgbBufferedImage = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_BYTE_INDEXED, cm);
        Graphics2D graphics2D = rgbBufferedImage.createGraphics();
       graphics2D.drawImage(bufferedImage, 0, 0, newWidth, newHeight, null);
        graphics2D.dispose();

        ImageWriter writer = ImageIO.getImageWritersByFormatName("png").next();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        writer.setOutput(new MemoryCacheImageOutputStream(baos));
        IIOImage outputImage = new IIOImage(rgbBufferedImage, null, null);
        try {
            //writer.write(null, outputImage, jpgWriteParam);
            writer.write(outputImage);
        } catch (IOException e) {
            e.printStackTrace();
            throw new IllegalArgumentException(e.getMessage(), e);
        }
        writer.dispose();

        byte[] returnImage = null;
        try {
            baos.flush();
            returnImage = baos.toByteArray();
            baos.close();
        } catch (IOException e) {
            e.printStackTrace();
            throw new IllegalArgumentException(e.getMessage(), e);
        }
        return returnImage;
    }