2 * Copyright 2007 Google Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 package com.google.zxing.client.j2me;
19 import com.google.zxing.MonochromeBitmapSource;
20 import com.google.zxing.common.BitArray;
21 import com.google.zxing.common.BlackPointEstimator;
23 import javax.microedition.lcdui.Image;
26 * @author Sean Owen (srowen@google.com)
28 final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
30 private final int[] rgbPixels;
31 private final int blackPoint;
32 private final int width;
33 private final int height;
35 LCDUIImageMonochromeBitmapSource(final Image image) {
36 int width = image.getWidth();
37 int height = image.getHeight();
40 int[] rgbPixels = new int[width * height];
41 this.rgbPixels = rgbPixels;
42 image.getRGB(rgbPixels, 0, width, 0, 0, width, height);
43 int[] luminanceBuckets = new int[32];
44 int minDimension = width < height ? width : height;
45 for (int n = 0, offset = 0; n < minDimension; n++, offset += width + 1) {
46 luminanceBuckets[computeRGBLuminance(rgbPixels[offset]) >> 3]++;
48 blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
51 public boolean isBlack(int x, int y) {
52 return computeRGBLuminance(rgbPixels[x + y * width]) < blackPoint;
55 public BitArray getBlackRow(int y, BitArray row, int startX, int getWidth) {
57 row = new BitArray(getWidth);
61 for (int i = 0, offset = y * width + startX; i < getWidth; i++, offset++) {
62 if (computeRGBLuminance(rgbPixels[offset]) < blackPoint) {
69 public int getHeight() {
73 public int getWidth() {
78 * Extracts luminance from a pixel from this source. By default, the source is assumed to use RGB,
79 * so this implementation computes luminance is a function of a red, green and blue components as
82 * <code>Y = 0.299R + 0.587G + 0.114B</code>
84 * where R, G, and B are values in [0,1].
86 private static int computeRGBLuminance(int pixel) {
87 // Coefficients add up to 1024 to make the divide into a fast shift
88 return (306 * ((pixel >> 16) & 0xFF) +
89 601 * ((pixel >> 8) & 0xFF) +
90 117 * (pixel & 0xFF)) >> 10;