/*
- * Copyright (C) 2008 Google Inc.
+ * Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
package com.google.zxing.client.android;
import android.graphics.Bitmap;
-import com.google.zxing.BlackPointEstimationMethod;
-import com.google.zxing.MonochromeBitmapSource;
-import com.google.zxing.ReaderException;
-import com.google.zxing.common.BitArray;
-import com.google.zxing.common.BlackPointEstimator;
+import com.google.zxing.common.BaseMonochromeBitmapSource;
/**
- * This object implements MonochromeBitmapSource around an Android Bitmap. Rather than capturing an
- * RGB image and calculating the grey value at each pixel, we ask the camera driver for YUV data and
- * strip out the luminance channel directly. This should be faster but provides fewer bits, i.e.
- * fewer grey levels.
+ * This object implements MonochromeBitmapSource around an Android Bitmap.
*
* @author dswitkin@google.com (Daniel Switkin)
* @author srowen@google.com (Sean Owen)
*/
-final class RGBMonochromeBitmapSource implements MonochromeBitmapSource {
+final class RGBMonochromeBitmapSource extends BaseMonochromeBitmapSource {
private final Bitmap 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;
+ private final int[] rgbRow;
+ private int cachedRow;
RGBMonochromeBitmapSource(Bitmap image) {
this.image = image;
- blackPoint = 0x7F;
- lastMethod = null;
- lastArgument = 0;
- }
-
- public boolean isBlack(int x, int y) {
- return computeRGBLuminance(image.getPixel(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 = new int[getWidth];
- image.getPixels(pixelRow, 0, getWidth, startX, y, getWidth, 1);
- for (int i = 0; i < getWidth; i++) {
- if (computeRGBLuminance(pixelRow[i]) < blackPoint) {
- row.set(i);
- }
- }
- return row;
+ rgbRow = new int[image.getWidth()];
+ cachedRow = -1;
}
public int getHeight() {
return image.width();
}
- public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) throws ReaderException {
- if (!method.equals(lastMethod) || argument != lastArgument) {
- int width = image.width();
- int height = image.height();
- int[] histogram = new int[LUMINANCE_BUCKETS];
- 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.getPixel(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);
- }
- int[] pixelRow = new int[width];
- image.getPixels(pixelRow, 0, width, 0, argument, width, 1);
- for (int x = 0; x < width; x++) {
- histogram[computeRGBLuminance(pixelRow[x]) >> LUMINANCE_SHIFT]++;
- }
- } else {
- throw new IllegalArgumentException("Unknown method: " + method);
- }
- blackPoint = BlackPointEstimator.estimate(histogram) << LUMINANCE_SHIFT;
- lastMethod = method;
- lastArgument = argument;
- }
- }
-
- public BlackPointEstimationMethod getLastEstimationMethod() {
- return lastMethod;
- }
-
- public MonochromeBitmapSource rotateCounterClockwise() {
- throw new IllegalStateException("Rotate not supported");
- }
-
- public boolean isRotateSupported() {
- return false;
- }
-
/**
* An optimized approximation of a more proper conversion from RGB to luminance which
- * only uses shifts. See BufferedImageMonochromeBitmapSource for an original version.
+ * only uses shifts.
*/
- private static int computeRGBLuminance(int pixel) {
+ public int getLuminance(int x, int y) {
+ int pixel;
+ if (cachedRow == y) {
+ pixel = rgbRow[x];
+ } else {
+ pixel = image.getPixel(x, y);
+ }
+
// Instead of multiplying by 306, 601, 117, we multiply by 256, 512, 256, so that
// the multiplies can be implemented as shifts.
//
// That is, we're replacing the coefficients in the original with powers of two,
// which can be implemented as shifts, even though changing the coefficients slightly
// corrupts the conversion. Not significant for our purposes.
- //
- // But we can get even cleverer and eliminate a few shifts:
- return (((pixel & 0x00FF0000) >> 8) +
- ((pixel & 0x0000FF00) << 1) +
- ((pixel & 0x000000FF) << 8)) >> 10;
+ return (((pixel & 0x00FF0000) >> 16) +
+ ((pixel & 0x0000FF00) >> 7) +
+ (pixel & 0x000000FF )) >> 2;
+ }
+
+ public void cacheRowForLuminance(int y) {
+ if (y != cachedRow) {
+ int width = image.width();
+ image.getPixels(rgbRow, 0, width, 0, y, width, 1);
+ cachedRow = y;
+ }
}
-}
\ No newline at end of file
+}
projects / zxing.git / blobdiff