display grayscale image in java

Question

I created 2D array of floats in java, representing gray scale image, when each pixel is normalized - it between [0,1].

How can I take the 2D array and display the image (in gray scale of course)?

ty!

Answer 1

The easiest way is to make a BufferedImage out of it. To do that, you'll have to convert the values into colors:

int toRGB(float value) {
    int part = Math.round(value * 255);
    return part * 0x10101;
}

That first converts the 0-1 range into 0-255 range, then produces a color where all three channels (RGB - red, green and blue) have the same value, which makes a gray.

Then, to make the whole image, set all the pixel values:

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int y = 0; y < height; y++)
    for (int x = 0; x < width; x++)
        image.setRGB(x, y, toRGB(theFloats[y][x]));

Once you have the image, you can save it to a file:

ImageIO.save(image, 'png', new File('some/path/file.png'));

Or, display it in some way, perhaps with Swing.. See for example this question.