Applying color to grayscale bitmaps?

Question

Hi,
This is more of a "how does InDesing do it" kind of question vs scripting, but since the InDesign developers hop on here once and a while, I thought I'd ask.  How does InDesign colorize grayscale images - is it doing a HSL transformation on each pixel, grabbing the S and L values for said pixel, and back-calculating a new RGB value for the target H value?
Thanks!

Answer 1

Were areas of your original image transparent?
Remember that by default all int arrays are popuated
with zeroes. In the case of an "RGB" format image,
that represents opaque black (transparent black in
"ARGB"). So when you create a new RGB image, it's
opaque black by default.
Otherwise, dunno, if your background was nearly white
but not quite (eg 0xfffefefe) maybe the threshold
makes any non-white value black. I've not converted
to binary images before, only from.Thanks !
I think that this is exactly the problem.
The problem is that I can't figure out where exactly I need to set the isOpaque property to true. I thougt maybe to scan the original image with a mask that sets alpha to opaque (is it 0x00 or 0xff ?), but it seems very inefficient to me. Is there another way ? Here is my code:
public static BufferedImage getBinaryImage(String filename) {
     BufferedImage originalImage = null, binaryImage;
     try {
          originalImage = ImageIO.read(new File(filename));
     } catch (IOException e) {
          System.out.println("Could not open file: " + filename);
          System.exit(1);
     binaryImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_BYTE_BINARY);
     binaryImage.createGraphics().drawImage(originalImage, 0, 0, null);
     return binaryImage;
}