Why Does Reading A Gif Or Png Containing Transparent/Alpha Pixels Fail?

Question

I'm trying to read in gif or png with transparent pixels into a BufferedImage so that I can create a font inside of Java. Right now, I'm defaulting to the assumption that the background of the font image is white. However, I want to make it so that the font background is whatever pixels happen to be transparent. The images I'm reading in have only two colors: black and white. I set all the white pixels to transparent when creating the images in hopes that I could do a check for all pixels with Alpha < 255. I have tried numerous possible solutions, such as saving the png files with different applications, ImageIO.read, and Toolkit.getDefaultToolkit().createImage, and JAI.The types of the resulting BufferedImages have varied between TYPE_BYTE_BINARY, TYPE_BYTE_INDEXED, and TYPE_CUSTOM. What I want is TYPE_INT_ARGB so I can get the dang alpha pixels.
1. Is there a way to read in alpha pixels of png or gif (doesn't have to be both) from within the main Java libraries as a BufferedImage with type TYPE_INT_ARGB? If so, how?
2. Failing that, is there a way to read in alpha pixels of png or gif (doesn't have to be both) by using a decent external library as a BufferedImage with type TYPE_INT_ARGB? If so, how and with which one?
This has been frustrating the heck out of me, since I thought this was something very simple to do, but I've spent two days poring over the entire Internet for a possible solution.

Answer 1

package aerobush.ocr.translator;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.image.BufferedImage;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;
import javax.media.jai.JAI;
import javax.media.jai.PlanarImage;
import com.sun.imageio.plugins.png.PNGMetadata;
public class ImageUtils
     static public BufferedImage readPng1(
               File pngFile ) {
          try {
               BufferedImage image = ImageIO.read(pngFile);
               return image;
          catch (Exception e) {}
          return null;
     static public BufferedImage readPng2(
               File pngFile ) {
          try {
               BufferedImage image = (BufferedImage) Toolkit.getDefaultToolkit().createImage(
                         pngFile.getAbsolutePath());
               return image;
          catch (Exception e) {}
          return null;
     static public BufferedImage readPng3(
               File pngFile ) {
          try {
               final PlanarImage planar = JAI.create(
                         "FileLoad",
                         pngFile.getAbsolutePath());
               BufferedImage img = planar.getAsBufferedImage();
               return img;
          catch (Exception e) {
               e.printStackTrace();
          return null;
     static public BufferedImage readPng4(
               File pngFile ) {
          try {
               ImageInputStream stream = ImageIO.createImageInputStream(new FileInputStream(
                         pngFile));
               ImageReader r = ImageIO.getImageReadersByFormatName(
                         "png").next();
               r.setInput(
                         stream,
                         true,
                         false);
               PNGMetadata metadata = (PNGMetadata) r.getImageMetadata(0);
               BufferedImage i = r.read(0);
               if (!i.getColorModel().hasAlpha() && metadata.tRNS_present) {
                    int alphaPix = (metadata.tRNS_red << 16) | (metadata.tRNS_green << 8)
                              | (metadata.tRNS_blue);
                    BufferedImage tmp = new BufferedImage(
                              i.getWidth(),
                              i.getHeight(),
                              BufferedImage.TYPE_INT_ARGB);
                    for (int x = 0; x < i.getWidth(); x++) {
                         for (int y = 0; y < i.getHeight(); y++) {
                              int rgb = i.getRGB(
                                        x,
                                        y);
                              rgb = (rgb & 0xFFFFFF) == alphaPix ? alphaPix : rgb;
                              tmp.setRGB(
                                        x,
                                        y,
                                        rgb);
                    i = tmp;
               return i;
          catch (IOException e) {}
          return null;
}Edited by: oldbushie on Sep 13, 2009 2:07 PM
Edited by: oldbushie on Sep 13, 2009 2:08 PM