When a BufferedImage is contsructed using the constructor:

BufferedImage(ColorModel, WritableRaster, boolean, Hashtable)

the type of the BufferedImage is inferred from the ColorModel and
WritableRaster. When an IndexColorModel is used along with a BytePackedRaster,
the type is taken to be TYPE_BYTE_BINARY, even when the number of bits
per pixel in the Raster is greater than 1. In this case, TYPE_BYTE_INDEXED
would seem to be more appropriate.

  Image display does not appear to be affected by this bug.

  A test program exhibiting this behavior is below:


import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.IndexColorModel;
import java.awt.image.MultiPixelPackedSampleModel;
import java.awt.image.SampleModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;

public class BufferedImageTest {

    public static void main(String[] args) {
        int width = 100;
        int height = 100;
        int bpp = 2;
        int colors = 1 << bpp;

        byte[] red = new byte[colors];
        byte[] green = new byte[colors];
        byte[] blue = new byte[colors];
        ColorModel cm = new IndexColorModel(bpp,
                                            colors,
                                            red,
                                            green,
                                            blue);

        SampleModel sm =
            new MultiPixelPackedSampleModel(DataBuffer.TYPE_BYTE,
                                            width,
                                            height,
                                            bpp);

        WritableRaster ras = Raster.createWritableRaster(sm, new Point(0, 0));

        BufferedImage bi = new BufferedImage(cm, ras, false, null);
        int type = bi.getType();
        System.out.println("BufferedImage type = " + type);
        System.out.println(" (TYPE_BYTE_BINARY = " +
                           BufferedImage.TYPE_BYTE_BINARY + ")");
        System.out.println(" (TYPE_BYTE_INDEXED = " +
                           BufferedImage.TYPE_BYTE_INDEXED + ")");
    }
}