Downgrading Image Resolution Using JAI

Question

I am interested in downgrading the resolution of TIFF images that I am inserting into a PDF to reduce the document's file size. The TIFF images are either CCITT G4 bitonal or JPEG RGB. What would be the best approach to doing this using JAI?
I appreciate any suggestions.
Youssef Eldakar
Bibliotheca Alexandrina

Answer 1

Youssef
The following code will load a TIFF image (or JPEG or some other formats that I can't remember) into a PlanarImage object and then rescale it according to the scale factors and then save as a TIFF.
For example if you wanted to change a 320 x 240 image to a 160 x 120 use xScaleFactor and yScaleFactor of 0.5.
  public static PlanarImage rescale(String inputFilename, String outputFilename, float xScaleFactor, float yScaleFactor)
        // load the image from the file
        PlanarImage image = JAI.create("fileload", inputFilename);
        ParameterBlock rescaleParameters = new ParameterBlock();
        rescaleParameters.addSource(image);
        rescaleParameters.add(xScaleFactor);
        rescaleParameters.add(yScaleFactor);
        // saving as TIFF is a little more complicated than loading
        try
            FileOutputStream out = new FileOutputStream(outputFilename);
            TIFFEncodeParam parameters = new TIFFEncodeParam();
            ImageEncoder encoder = ImageCodec.createImageEncoder("TIFF", out, parameters);
            try
                encoder.encode(image);
                out.close();
            catch (IOException e)
                System.out.println("Failed to encode the image");
        catch (java.io.FileNotFoundException ioEx)
            System.out.println("Could not write to file " + filename);