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Apache Commons Imaging (previously Sanselan) is a pure-Java image library.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.imaging.formats.tiff.datareaders;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.nio.ByteOrder;
import org.apache.commons.imaging.ImageReadException;
import org.apache.commons.imaging.common.ImageBuilder;
import org.apache.commons.imaging.formats.tiff.TiffDirectory;
import org.apache.commons.imaging.formats.tiff.TiffImageData;
import org.apache.commons.imaging.formats.tiff.photometricinterpreters.PhotometricInterpreter;
import org.apache.commons.imaging.formats.tiff.photometricinterpreters.PhotometricInterpreterRgb;
public final class DataReaderStrips extends ImageDataReader {
private final int bitsPerPixel;
private final int compression;
private final int rowsPerStrip;
private final ByteOrder byteOrder;
private int x;
private int y;
private final TiffImageData.Strips imageData;
public DataReaderStrips(final TiffDirectory directory,
final PhotometricInterpreter photometricInterpreter, final int bitsPerPixel,
final int[] bitsPerSample, final int predictor, final int samplesPerPixel, final int width,
final int height, final int compression, final ByteOrder byteOrder, final int rowsPerStrip,
final TiffImageData.Strips imageData) {
super(directory, photometricInterpreter, bitsPerSample, predictor,
samplesPerPixel, width, height);
this.bitsPerPixel = bitsPerPixel;
this.compression = compression;
this.rowsPerStrip = rowsPerStrip;
this.imageData = imageData;
this.byteOrder = byteOrder;
}
private void interpretStrip(
final ImageBuilder imageBuilder,
final byte[] bytes,
final int pixelsPerStrip,
final int yLimit) throws ImageReadException, IOException {
if (y >= yLimit) {
return;
}
// changes added May 2012
// In the original implementation, a general-case bit reader called
// getSamplesAsBytes is used to retrieve the samples (raw data values)
// for each pixel in the strip. These samples are then passed into a
// photogrammetric interpreter that converts them to ARGB pixel values
// and stores them in the image. Because the bit-reader must handle
// a large number of formats, it involves several conditional
// branches that must be executed each time a pixel is read.
// Depending on the size of an image, the same evaluations must be
// executed redundantly thousands and perhaps millions of times
// in order to process the complete collection of pixels.
// This code attempts to remove that redundancy by
// evaluating the format up-front and bypassing the general-format
// code for two commonly used data formats: the 8 bits-per-pixel
// and 24 bits-per-pixel cases. For these formats, the
// special case code achieves substantial reductions in image-loading
// time. In other cases, it simply falls through to the original code
// and continues to read the data correctly as it did in previous
// versions of this class.
// In addition to bypassing the getBytesForSample() method,
// the 24-bit case also implements a special block for RGB
// formatted images. To get a sense of the contributions of each
// optimization (removing getSamplesAsBytes and removing the
// photometric interpreter), consider the following results from tests
// conducted with large TIFF images using the 24-bit RGB format
// bypass getSamplesAsBytes: 67.5 % reduction
// bypass both optimizations: 77.2 % reduction
//
//
// Future Changes
// Both of the 8-bit and 24-bit blocks make the assumption that a strip
// always begins on x = 0 and that each strip exactly fills out the rows
// it contains (no half rows). The original code did not make this
// assumption, but the approach is consistent with the TIFF 6.0 spec
// (1992),
// and should probably be considered as an enhancement to the
// original general-case code block that remains from the original
// implementation. Taking this approach saves one conditional
// operation per pixel or about 5 percent of the total run time
// in the 8 bits/pixel case.
// verify that all samples are one byte in size
final boolean allSamplesAreOneByte = isHomogenous(8);
if (predictor != 2 && bitsPerPixel == 8 && allSamplesAreOneByte) {
int k = 0;
int nRows = pixelsPerStrip / width;
if (y + nRows > yLimit) {
nRows = yLimit - y;
}
final int i0 = y;
final int i1 = y + nRows;
x = 0;
y += nRows;
final int[] samples = new int[1];
for (int i = i0; i < i1; i++) {
for (int j = 0; j < width; j++) {
samples[0] = bytes[k++] & 0xff;
photometricInterpreter.interpretPixel(imageBuilder,
samples, j, i);
}
}
return;
} else if (predictor != 2 && bitsPerPixel == 24 && allSamplesAreOneByte) {
int k = 0;
int nRows = pixelsPerStrip / width;
if (y + nRows > yLimit) {
nRows = yLimit - y;
}
final int i0 = y;
final int i1 = y + nRows;
x = 0;
y += nRows;
if (photometricInterpreter instanceof PhotometricInterpreterRgb) {
for (int i = i0; i < i1; i++) {
for (int j = 0; j < width; j++, k += 3) {
final int rgb = 0xff000000
| (((bytes[k] << 8) | (bytes[k + 1] & 0xff)) << 8)
| (bytes[k + 2] & 0xff);
imageBuilder.setRGB(j, i, rgb);
}
}
} else {
final int[] samples = new int[3];
for (int i = i0; i < i1; i++) {
for (int j = 0; j < width; j++) {
samples[0] = bytes[k++] & 0xff;
samples[1] = bytes[k++] & 0xff;
samples[2] = bytes[k++] & 0xff;
photometricInterpreter.interpretPixel(imageBuilder,
samples, j, i);
}
}
}
return;
}
// ------------------------------------------------------------
// original code before May 2012 modification
// this logic will handle all cases not conforming to the
// special case handled above
try (final BitInputStream bis = new BitInputStream(new ByteArrayInputStream(bytes), byteOrder)) {
int[] samples = new int[bitsPerSampleLength];
resetPredictor();
for (int i = 0; i < pixelsPerStrip; i++) {
getSamplesAsBytes(bis, samples);
if (x < width) {
samples = applyPredictor(samples);
photometricInterpreter.interpretPixel(imageBuilder, samples, x, y);
}
x++;
if (x >= width) {
x = 0;
resetPredictor();
y++;
bis.flushCache();
if (y >= yLimit) {
break;
}
}
}
}
}
@Override
public void readImageData(final ImageBuilder imageBuilder)
throws ImageReadException, IOException {
for (int strip = 0; strip < imageData.getImageDataLength(); strip++) {
final long rowsPerStripLong = 0xFFFFffffL & rowsPerStrip;
final long rowsRemaining = height - (strip * rowsPerStripLong);
final long rowsInThisStrip = Math.min(rowsRemaining, rowsPerStripLong);
final long bytesPerRow = (bitsPerPixel * width + 7) / 8;
final long bytesPerStrip = rowsInThisStrip * bytesPerRow;
final long pixelsPerStrip = rowsInThisStrip * width;
final byte[] compressed = imageData.getImageData(strip).getData();
final byte[] decompressed = decompress(compressed, compression,
(int) bytesPerStrip, width, (int) rowsInThisStrip);
interpretStrip(
imageBuilder,
decompressed,
(int) pixelsPerStrip,
height);
}
}
@Override
public BufferedImage readImageData(final Rectangle subImage)
throws ImageReadException, IOException {
// the legacy code is optimized to the reading of whole
// strips (except for the last strip in the image, which can
// be a partial). So create a working image with compatible
// dimensions and read that. Later on, the working image
// will be sub-imaged to the proper size.
// strip0 and strip1 give the indices of the strips containing
// the first and last rows of pixels in the subimage
final int strip0 = subImage.y / rowsPerStrip;
final int strip1 = (subImage.y + subImage.height - 1) / rowsPerStrip;
final int workingHeight = (strip1 - strip0 + 1) * rowsPerStrip;
// the legacy code uses a member element "y" to keep track
// of the row index of the output image that is being processed
// by interpretStrip. y is set to zero before the first
// call to interpretStrip. y0 will be the index of the first row
// in the full image (the source image) that will be processed.
final int y0 = strip0 * rowsPerStrip;
final int yLimit = subImage.y - y0 + subImage.height;
// TO DO: we can probably save some processing by using yLimit instead
// or working
final ImageBuilder workingBuilder =
new ImageBuilder(width, workingHeight, false);
for (int strip = strip0; strip <= strip1; strip++) {
final long rowsPerStripLong = 0xFFFFffffL & rowsPerStrip;
final long rowsRemaining = height - (strip * rowsPerStripLong);
final long rowsInThisStrip = Math.min(rowsRemaining, rowsPerStripLong);
final long bytesPerRow = (bitsPerPixel * width + 7) / 8;
final long bytesPerStrip = rowsInThisStrip * bytesPerRow;
final long pixelsPerStrip = rowsInThisStrip * width;
final byte[] compressed = imageData.getImageData(strip).getData();
final byte[] decompressed = decompress(compressed, compression,
(int) bytesPerStrip, width, (int) rowsInThisStrip);
interpretStrip(
workingBuilder,
decompressed,
(int) pixelsPerStrip,
yLimit);
}
if (subImage.x == 0
&& subImage.y == y0
&& subImage.width == width
&& subImage.height == workingHeight) {
// the subimage exactly matches the ImageBuilder bounds
return workingBuilder.getBufferedImage();
}
return workingBuilder.getSubimage(
subImage.x,
subImage.y - y0,
subImage.width,
subImage.height);
}
}