| /* |
| * Copyright 2007 Google Inc. |
| * |
| * Licensed 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 com.google.zxing.client.j2se; |
| |
| import com.google.zxing.BlackPointEstimationMethod; |
| import com.google.zxing.MonochromeBitmapSource; |
| import com.google.zxing.common.BitArray; |
| import com.google.zxing.common.BlackPointEstimator; |
| |
| import java.awt.geom.AffineTransform; |
| import java.awt.image.AffineTransformOp; |
| import java.awt.image.BufferedImage; |
| import java.awt.image.BufferedImageOp; |
| |
| /** |
| * <p>An implementation based upon {@link BufferedImage}. This provides access to the |
| * underlying image as if it were a monochrome image. Behind the scenes, it is evaluating |
| * the luminance of the underlying image by retrieving its pixels' RGB values.</p> |
| * |
| * @author srowen@google.com (Sean Owen), Daniel Switkin (dswitkin@google.com) |
| */ |
| public final class BufferedImageMonochromeBitmapSource implements MonochromeBitmapSource { |
| |
| private final BufferedImage image; |
| private int blackPoint; |
| private BlackPointEstimationMethod lastMethod; |
| private int lastArgument; |
| |
| private static final int LUMINANCE_BITS = 5; |
| private static final int LUMINANCE_SHIFT = 8 - LUMINANCE_BITS; |
| private static final int LUMINANCE_BUCKETS = 1 << LUMINANCE_BITS; |
| |
| public BufferedImageMonochromeBitmapSource(BufferedImage image) { |
| this.image = image; |
| blackPoint = 0x7F; |
| lastMethod = null; |
| lastArgument = 0; |
| } |
| |
| public boolean isBlack(int x, int y) { |
| return computeRGBLuminance(image.getRGB(x, y)) < blackPoint; |
| } |
| |
| public BitArray getBlackRow(int y, BitArray row, int startX, int getWidth) { |
| if (row == null) { |
| row = new BitArray(getWidth); |
| } else { |
| row.clear(); |
| } |
| int[] pixelRow = image.getRGB(startX, y, getWidth, 1, null, 0, getWidth); |
| for (int i = 0; i < getWidth; i++) { |
| if (computeRGBLuminance(pixelRow[i]) < blackPoint) { |
| row.set(i); |
| } |
| } |
| return row; |
| } |
| |
| public int getHeight() { |
| return image.getHeight(); |
| } |
| |
| public int getWidth() { |
| return image.getWidth(); |
| } |
| |
| public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) { |
| if (!method.equals(lastMethod) || argument != lastArgument) { |
| int width = image.getWidth(); |
| int height = image.getHeight(); |
| int[] histogram = new int[LUMINANCE_BUCKETS]; |
| float biasTowardsWhite = 1.0f; |
| if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) { |
| int minDimension = width < height ? width : height; |
| int startI = height == minDimension ? 0 : (height - width) >> 1; |
| int startJ = width == minDimension ? 0 : (width - height) >> 1; |
| for (int n = 0; n < minDimension; n++) { |
| int pixel = image.getRGB(startJ + n, startI + n); |
| histogram[computeRGBLuminance(pixel) >> LUMINANCE_SHIFT]++; |
| } |
| } else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) { |
| if (argument < 0 || argument >= height) { |
| throw new IllegalArgumentException("Row is not within the image: " + argument); |
| } |
| biasTowardsWhite = 2.0f; |
| int[] rgbArray = new int[width]; |
| image.getRGB(0, argument, width, 1, rgbArray, 0, width); |
| for (int x = 0; x < width; x++) { |
| histogram[computeRGBLuminance(rgbArray[x]) >> LUMINANCE_SHIFT]++; |
| } |
| } else { |
| throw new IllegalArgumentException("Unknown method: " + method); |
| } |
| blackPoint = BlackPointEstimator.estimate(histogram, biasTowardsWhite) << LUMINANCE_SHIFT; |
| lastMethod = method; |
| lastArgument = argument; |
| } |
| } |
| |
| public BlackPointEstimationMethod getLastEstimationMethod() { |
| return lastMethod; |
| } |
| |
| public MonochromeBitmapSource rotateCounterClockwise() { |
| // 90 degrees counterclockwise: |
| AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, image.getHeight()); |
| BufferedImageOp op = new AffineTransformOp(transform, AffineTransformOp.TYPE_NEAREST_NEIGHBOR); |
| BufferedImage rotatedImage = new BufferedImage(image.getHeight(), image.getWidth(), image.getType()); |
| op.filter(image, rotatedImage); |
| return new BufferedImageMonochromeBitmapSource(rotatedImage); |
| } |
| |
| public boolean isRotatedSupported() { |
| return true; |
| } |
| |
| /** |
| * Extracts luminance from a pixel from this source. By default, the source is assumed to use RGB, |
| * so this implementation computes luminance is a function of a red, green and blue components as |
| * follows: |
| * |
| * <code>Y = 0.299R + 0.587G + 0.114B</code> |
| * |
| * where R, G, and B are values in [0,1]. |
| */ |
| private static int computeRGBLuminance(int pixel) { |
| // Coefficients add up to 1024 to make the divide into a fast shift |
| return (306 * ((pixel >> 16) & 0xFF) + |
| 601 * ((pixel >> 8) & 0xFF) + |
| 117 * (pixel & 0xFF)) >> 10; |
| } |
| |
| } |