Get the data (palette indices) of an indexed image

Question

How can I access the image data (array of palette indices) of an indexed image (png8 or gif)?

Example:

• Image palette: {0xFF0000, 0x00FF00, 0x0000FF}
• Image data: {0,1,1,0,1,2,2,2,0,1,0,2,0,1,1,0}

What I need is:

ArrayList<Integer> getImageData(File image) {
  /* ??? */
}

Answer 1

The code below will read the image data into imageData, an array of int values.

  BufferedImage image = ImageIO.read(imageFile);
  int width = image.getWidth();
  int height = image.getHeight();
  int[] imageData = new int[width * height * image.getColorModel().getNumComponents()];
  imageData = image.getData().getPixels(0, 0, width, height, imageData);