getRBG doesn't return value set by setRGB in java swing, buffered Image

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Java

BufferedImage bimg = ImageIO.read(fc.getSelectedFile());
bimg.setRGB(0, 0, 1234);
int x = bimg.getRGB(0,0);

in the above code i didn't get x as 1234 why ?

Posted 7-Feb-13 23:54pm

manuthebos

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Fredrik Bornander · Answer 1 · 2013-02-08T00:49:00

That is because in BufferedImages with a ColorModel the pixel is set to the nearest colour chosen. That means that you might not get the colour you wanted because the colours you can set are limited to the colours in the ColorModel.

You can get around that by creating your own BufferedImage and draw the source image onto that and then manipulate those pixels;

Java

package com.bornander.test;

import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

public class Program {
	
  public static void main(String[] args) throws Exception {
    BufferedImage src = ImageIO.read(new File("C:\\Temp\\SomeImage.png"));
    BufferedImage dst = new BufferedImage(src.getWidth(), src.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
    dst.getGraphics().drawImage(src, 0, 0, null);
		
    System.out.println("Before: " + dst.getRGB(0, 0));
    dst.setRGB(0, 0, 1234);
    System.out.println("After : " + dst.getRGB(0, 0));
  }
}

Hope this helps,
Fredrik