Filtering rgb image works only one time in java

Question

I want to filter my BufferedImage in java.
Currently, I have this piece of code:

private void changeRGB(BufferedImage image, int colour) {
    int width = image.getWidth();
    int height = image.getHeight();
    int newColor = 0;

    for(int y = 0; y < height; y++){
      for(int x = 0; x < width; x++){
          Color color = new Color(image.getRGB(x,y));

          int red = color.getRed();
          int green = color.getGreen();
          int blue = color.getBlue();

          if (colour == 1) {
              newColor = new Color(red, 0, 0).getRGB();
          } else if (colour == 2) {
              newColor = new Color(0, green, 0).getRGB();
          } else if (colour == 3) {
              newColor = new Color(0, 0, blue).getRGB();
          }

          image.setRGB(x, y, newColor);
      }
    }
    icon = new ImageIcon(image);
    this.lblFilteredImage.setIcon(icon);
}

and if I press e.g. the red, green or blue button I do it this way:

choice = 2; changeRGB(img, choice);

This code works one time and if I press one of these buttons the 2nd time it doesn't work anymore

`color` and `colour` variables in the same scope? You should definetly change one of those variable names... Furthermore if applied more than once to the same image, the image either does not change, since you extract the same channel you already extracted or the image becomes black, since you extract a color that was set to 0 before... — fabian, Sep 24 '16 at 08:55
Ok but how can I solve that issue so the image doesn't get black? — mafioso, Sep 24 '16 at 09:15
Use 2 Images, one with the source and the other with the filtered data. Applying different filters does not make sense in with those filters; so I guess you want to apply only one of these filters at once. — fabian, Sep 24 '16 at 09:23

score 1 · Answer 1 · answered Sep 24 '16 at 10:08

it seems you are modifying the "source" image stored in the BufferedImage, use a new BufferedImage to store the result and thus avoid destroying your source image.

you can try it this way, so the "source" image is left unaltered.

private void changeRGB(BufferedImage image,int colour)
{
    int width=image.getWidth();
    int height=image.getHeight();
    int newColor=0;
    BufferedImage tempBuffer=new BufferedImage(image.getWidth(), image.getHeight(), image.getType());
    for(int y=0;y<height;y++)
    {
        for(int x=0;x<width;x++)
        {
            Color color=new Color(image.getRGB(x, y));

            int red=color.getRed();
            int green=color.getGreen();
            int blue=color.getBlue();

            if(colour==1)
            {
                newColor=new Color(red, 0, 0).getRGB();
            }
            else if(colour==2)
            {
                newColor=new Color(0, green, 0).getRGB();
            }
            else if(colour==3)
            {
                newColor=new Color(0, 0, blue).getRGB();
            }

            tempBuffer.setRGB(x, y, newColor);
        }
    }
    icon=new ImageIcon(tempBuffer);
    this.lblFilteredImage.setIcon(icon);
}

score 0 · Answer 2 · edited May 23 '17 at 12:33

0

I think Alex is right. BufferedImage is mutable, so changeRGB changes the "original" BufferedImage.
Clone the BufferedImage and process the clone.

edited May 23 '17 at 12:33

Community

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answered Sep 24 '16 at 11:05

c0der

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Feedback would be appreciated – c0der Oct 27 '17 at 16:54

Filtering rgb image works only one time in java

2 Answers2