Question

I already asked a Question how to save large images and I think I’m on the right track but I still need some advice.

I have an Image 12000 x 12000 and I need to save it as .png

BufferedImage can’t be used.

I was already advised to use the RenderedImage interface but somehow I can’t get the desired result. ( I haven’t worked with rasters yet so probably I got something wrong )

Code for the saving image method:

   public static void SavePanel() {

    PanelImage IMAGE = new PanelImage(panel);

    try {
        ImageIO.write(IMAGE, "png", new File(ProjectNameTxt.getText() +  ".png"));
    } catch (IOException e) {
    }

   }

And code for the PanelImage class:

 public static class PanelImage implements RenderedImage {

    // some variables here

    public PanelImage(JImagePanel panel) {
       this.panel = panel;
    }

  public Raster getData(Rectangle rect) {

        sizex = (int) rect.getWidth();
        sizey += (int) rect.getHeight();
        image = null;
        image = new BufferedImage(
                (int) sizex,
                (int) sizey,
                BufferedImage.TYPE_INT_RGB);
        g2 = image.createGraphics();
        panel.paintComponent(g2);
        return image.getData();
    }

 // rest of the implemented methods - no problems here
 }

I noticed that the ImageIO requests one line of pixels at a time ( 12000 x 1 ).
This method is working but I still need the whole image in the BufferedImage.
I have to increase the size of the BImage each time ImageIO calls the method, otherwise I get ” Coordinate out of bounds! ” exeption

Thanks

Answer 1

This PNGJ library can be useful to read/write huge images, because it does it sequentially, it only keeps a line in memory at a time. (I wrote it myself a while ago, because I had a similar need)