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Description
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FULL PRODUCT VERSION :
java version "1.4.2_05"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_05-b04)
Java HotSpot(TM) Client VM (build 1.4.2_05-b04, mixed mode)
ADDITIONAL OS VERSION INFORMATION :
customer Windows 2000 [Version 5.00.2195
EXTRA RELEVANT SYSTEM CONFIGURATION :
JAI Image I/O Tools
A DESCRIPTION OF THE PROBLEM :
PNG subsampling with JAI Image I/O Tools introduce an erroneous offset by one as seen from the enclosed program and its output. If JAI Image I/O Tools are not used, the PNG subsampling works as expected.
STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the enclosed program
EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
0 2 4 6 8 10 12 14 16 18
0 2 4 6 8 10 12 14 16 18
ACTUAL -
0 2 4 6 8 10 12 14 16 18
1 3 5 7 9 11 13 15 17 19
REPRODUCIBILITY :
This bug can be reproduced always.
---------- BEGIN SOURCE ----------
package com.picturegrid.playground;
import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.ComponentColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.DataBufferByte;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;
public class Test
{
public static BufferedImage createTestImage(int w, int h)
{
byte[][] data = new byte[3][w * h];
for(int x = 0; x < w; ++x)
for(int y = 0; y < h; ++y)
{
data[0][w * y + x] = (byte) (x & 0xff);
data[1][w * y + x] = (byte) ((x + y) >>> 1 & 0xff);
data[2][w * y + x] = (byte) (y & 0xff);
}
DataBuffer dataBuffer = new DataBufferByte(data, w * h);
WritableRaster raster = Raster.createBandedRaster(dataBuffer, w, h, w, new int[] { 0, 1, 2 }, new int[] { 0, 0, 0 }, null);
ColorModel cm = new ComponentColorModel(ColorSpace.getInstance(ColorSpace.CS_sRGB), new int[] { 8, 8, 8 }, false, false, ColorModel.OPAQUE, raster.getTransferType());
return new BufferedImage(cm, raster, cm.isAlphaPremultiplied(), null);
}
private static void write(BufferedImage image, File file) throws IOException
{
ImageWriter writer = (ImageWriter) ImageIO.getImageWritersBySuffix(suffix(file)).next();
RandomAccessFile raf = new RandomAccessFile(file, "rw");
ImageOutputStream ios = ImageIO.createImageOutputStream(raf);
writer.setOutput(ios);
writer.write(image);
writer.dispose();
raf.close();
}
private static BufferedImage read(File file, int xStart, int yStart, int xStep, int yStep) throws IOException
{
ImageReader reader = (ImageReader) ImageIO.getImageReadersBySuffix(suffix(file)).next();
ImageReadParam param = reader.getDefaultReadParam();
param.setSourceSubsampling(xStep, yStep, xStart, yStart);
RandomAccessFile raf = new RandomAccessFile(file, "r");
ImageInputStream iis = ImageIO.createImageInputStream(raf);
reader.setInput(iis);
BufferedImage image = reader.read(0, param);
reader.dispose();
raf.close();
return image;
}
private static String suffix(File file)
{
String fileName = file.getName();
int i = fileName.lastIndexOf('.');
return fileName.substring(i + 1);
}
private static void println(BufferedImage image, int band, int xStart, int yStart, int xStep, int yStep, int w, int h)
{
int[] samples = image.getRaster().getSamples(xStart, yStart, w, h, band, (int[]) null);
for(int y = 0; y < h; y += yStep)
{
for(int x = 0; x < w; x += xStep)
System.out.print(samples[x + w * y] + " ");
System.out.println();
}
}
public static void main(String[] args) throws IOException
{
int xStart = 0;
int yStart = 0;
int xStep = 2;
int yStep = 2;
int w = 20;
int h = 1;
File file = new File("test.png");
file.deleteOnExit();
BufferedImage imageBefore = createTestImage(256, 256);
write(imageBefore, file);
BufferedImage imageAfter = read(file, xStart, yStart, xStep, yStep);
println(imageBefore, 0, xStart, yStart, xStep, yStep, w, h);
println(imageAfter, 0, 0, 0, 1, 1, (w - xStart + xStep - 1) / xStep, (h - yStart + yStep - 1) / yStep);
}
}
---------- END SOURCE ----------
CUSTOMER SUBMITTED WORKAROUND :
Don't use JAI Image I/O Tools
(Incident Review ID: 310766)
======================================================================p
xxxxx@xxxxx 10/7/04 01:33 GMT
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