Autoscale range 16-bit grayscale image in Java

Question

I have an 12-bit grayscale image. I want to display it in Java with BufferedImage, and I find BufferedImage.TYPE_USHORT_GRAY is the most suitable. However, it makes my display image almost black (my pixels are in 0 ~ 4095 range).

How can I autoscale it to clearly display it?

Thanks so much.

Answer 1

If your data is stored as 16 bit samples (as indicated in the comments), then you can either:

• Multiply the samples (by 16) to the full 16 bit range, and create a BufferedImage.TYPE_USHORT_GRAY image. Straight forward, but requires massaging and copying the data.

• Or, you could also create a custom BufferedImage with a 12 bit ColorModel, and just use the data as is. Probably faster, but more verbose/complicated code.

Here's the code to create an image using a 12 bit gray color model:

WritableRaster raster = Raster.createInterleavedRaster(new DataBufferUShort(twelveBitData, twelveBitData.length), w, h, w, 1, new int[]{0}, null);

ColorSpace gray = ColorSpace.getInstance(ColorSpace.CS_GRAY);
ColorModel twelveBitModel = new ComponentColorModel(gray, new int[]{12}, false, false, Transparency.OPAQUE, DataBuffer.TYPE_USHORT);
BufferedImage image = new BufferedImage(twelveBitModel, raster, twelveBitModel.isAlphaPremultiplied(), null);

Full, runnable demo program below.

Alternatively, if your data had been stored as "one and a half byte" packed 12 bit samples, the simplest solution would be to first pad the data to full 16 bit samples.

---

Demo program:

public class TwelveBit {

    public static void main(String[] args) {
        int w = 320;
        int h = 200;
        short[] twelveBitData = new short[w * h];

        createRandomData(twelveBitData);

        WritableRaster raster = Raster.createInterleavedRaster(new DataBufferUShort(twelveBitData, twelveBitData.length), w, h, w, 1, new int[]{0}, null);

        ColorSpace gray = ColorSpace.getInstance(ColorSpace.CS_GRAY);
        ColorModel twelveBitModel = new ComponentColorModel(gray, new int[]{12}, false, false, Transparency.OPAQUE, DataBuffer.TYPE_USHORT);
        BufferedImage image = new BufferedImage(twelveBitModel, raster, twelveBitModel.isAlphaPremultiplied(), null);

        showIt(image);

    }

    private static void createRandomData(short[] twelveBitData) {
        Random random = new Random();
        for (int i = 0; i < twelveBitData.length; i++) {
            twelveBitData[i] = (short) random.nextInt(1 << 12);
        }
    }

    private static void showIt(final BufferedImage image) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame("test");
                frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

                frame.add(new JLabel(new ImageIcon(image)));

                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}