Grayscale to RGB

Question

Hello,
I am trying to convert a grayscale image (pixelBits = 8 numComponents = 1) to an rgb image (pixelBits = 24 numComponents = 3).
There are many tutorials to convert RBG to grayscale but not the opposite...
Any idea ?
Thanks.

Answer 1

Hi Yann,
Thanks for your useful post.
Unfortunately there's still little defect : result operation colormodel is not explicitly specified, which leads to strange background rendering when using backgroundValues parameter in "rotate" operation.
So here the enhanced code :
PlanarImage src = JAI.create("fileload", "Photo.jpg";);
System.out.println(src.getColorModel());
// Prepare operation parameters
double[][] matrix = {
     { 1.0D, 0.0D },
     { 1.0D, 0.0D },
     { 1.0D, 0.0D } };
ParameterBlock pb = new ParameterBlock();
pb.addSource(src);
pb.add(matrix);
// Prepare rendering hints
ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_sRGB);
ColorModel cm = RasterFactory.createComponentColorModel(
     DataBuffer.TYPE_BYTE, cs, false, false,
     Transparency.OPAQUE);
SampleModel sm = cm.createCompatibleSampleModel(image.getWidth(), image.getHeight());
ImageLayout imageLayout = new ImageLayout();
imageLayout.setSampleModel(sm);
imageLayout.setColorModel(cm);
RenderingHints renderingHints = new RenderingHints(null);
renderingHints.clear();
renderingHints.put(JAI.KEY_IMAGE_LAYOUT, imageLayout);
// Perform the band combine operation.
PlanarImage dst = (PlanarImage)JAI.create("bandcombine", pb, renderingHints);
System.out.println(dst .getColorModel());