FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)


ADDITIONAL OS VERSION INFORMATION :
Linux Brisbane 2.6.22-14-generic #1 SMP Tue Feb 12 07:42:25 UTC 2008 i686 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
It appears that some PNGs with an alpha channel, lose the alpha channel when loaded with ImageIO.read.

The test code provided loads an image from a URL (the image is a PNG from a Web Map Server, which has transparency). If you open this same image in an image viewer application, you can see that it does indeed have a transparency.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the ReproduceBug class, then run its main method.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Does image have an alpha channel? >> YES
ACTUAL -
Does image have an alpha channel? >> NO

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;

public class ReproduceBug {

    public static void main(String[] args) {
        try {
        BufferedImage shouldHaveAlpha = ImageIO.read(new URL("http://www.webgis.nrm.qld.gov.au/wmsconnector/com.esri.wms.Esrimap/NAP_RIS_Portal" +
                    "?VERSION=1&SRS=EPSG%3A4326&transparent=true" +
                    "&request=GetMap&styles=&format=image%2Fpng&layers=naptwnp%2Croad25ml%2Cdrain25ml" +
                    "&bbox=139.11712858077894,-20.64651565636843,146.84497668237893,-14.20664223836843" +
                    "&width=32&height=32"));

            System.out.println("Does image have an alpha channel? >> " +
                    ((shouldHaveAlpha.getAlphaRaster() == null) ? "NO" : "YES"));

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
None as yet.