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Implemented row sampling for histograms and tweaked the valley finding algorithm

Browse source 
for better performance.


git-svn-id: https://zxing.googlecode.com/svn/trunk@56 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
dswitkin 2007-11-19 17:26:22 +00:00
parent eb52d61f46
commit 25d112c554
5 changed files with 73 additions and 38 deletions
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26
core/src/com/google/zxing/common/BlackPointEstimator.java
View file

@ -36,21 +36,21 @@ public final class BlackPointEstimator {
* decides which bucket of values corresponds to the black point -- which bucket contains the
* count of the brightest luminance values that should be considered "black".</p>
*
* @param luminanceBuckets an array of <em>counts</em> of luminance values
* @param histogram an array of <em>counts</em> of luminance values
* @return index within argument of bucket corresponding to brightest values which should be
* considered "black"
*/
public static int estimate(int[] luminanceBuckets) {
public static int estimate(int[] histogram) {
int numBuckets = luminanceBuckets.length;
int numBuckets = histogram.length;
// Find tallest peak in histogram
int firstPeak = 0;
int firstPeakSize = 0;
for (int i = 0; i < numBuckets; i++) {
if (luminanceBuckets[i] > firstPeakSize) {
if (histogram[i] > firstPeakSize) {
firstPeak = i;
firstPeakSize = luminanceBuckets[i];
firstPeakSize = histogram[i];
}
}
@ -61,7 +61,7 @@ public final class BlackPointEstimator {
for (int i = 0; i < numBuckets; i++) {
int distanceToBiggest = i - firstPeak;
// Encourage more distant second peaks by multiplying by square of distance
int score = luminanceBuckets[i] * distanceToBiggest * distanceToBiggest;
int score = histogram[i] * distanceToBiggest * distanceToBiggest;
if (score > secondPeakScore) {
secondPeak = i;
secondPeakScore = score;
@ -75,13 +75,13 @@ public final class BlackPointEstimator {
secondPeak = temp;
}
// Find a valley between them that is low and close to the midpoint of the two peaks
int bestValley = firstPeak;
int bestValleyScore = 0;
for (int i = firstPeak + 1; i < secondPeak; i++) {
// Encourage low valleys near the mid point between peaks
int score = (firstPeakSize - luminanceBuckets[i]) * (i - firstPeak) * (secondPeak - i);
if (score > bestValleyScore) {
// Find a valley between them that is low and closer to the white peak
int bestValley = secondPeak;
int bestValleyScore = Integer.MAX_VALUE;
for (int i = secondPeak; i > firstPeak; i--) {
int distance = secondPeak - i + 3;
int score = distance * histogram[i];
if (score < bestValleyScore) {
bestValley = i;
bestValleyScore = score;
}

2
core/src/com/google/zxing/upc/UPCDecoder.java
View file

@ -16,6 +16,7 @@
package com.google.zxing.upc;
import com.google.zxing.BlackPointEstimationMethod;
import com.google.zxing.common.BitArray;
import com.google.zxing.MonochromeBitmapSource;
@ -66,6 +67,7 @@ final class UPCDecoder {
int found = -1;
for (int x = 0; x < BITMAP_SEARCH_PATTERN.length; x++) {
int row = height * BITMAP_SEARCH_PATTERN[x] / 100;
bitmap.estimateBlackPoint(BlackPointEstimationMethod.ROW_SAMPLING, row);
bitmap.getBlackRow(row, rowData, 0, width);
if (decodeRow(rowData)) {

34
javame/src/com/google/zxing/client/j2me/LCDUIImageMonochromeBitmapSource.java
View file

@ -35,6 +35,11 @@ final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
private final int height;
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;
LCDUIImageMonochromeBitmapSource(final Image image) {
width = image.getWidth();
@ -42,6 +47,8 @@ final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
rgbPixels = new int[width * height];
image.getRGB(rgbPixels, 0, width, 0, 0, width, height);
blackPoint = 0x7F;
lastMethod = null;
lastArgument = 0;
}
public boolean isBlack(int x, int y) {
@ -71,21 +78,28 @@ final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
}
public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(lastMethod)) {
int[] luminanceBuckets = new int[32];
if (!method.equals(lastMethod) || argument != lastArgument) {
int[] histogram = new int[LUMINANCE_BUCKETS];
if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
int minDimension = width < height ? width : height;
for (int n = 0, offset = 0; n < minDimension; n++, offset += width + 1) {
luminanceBuckets[computeRGBLuminance(rgbPixels[offset]) >> 3]++;
histogram[computeRGBLuminance(rgbPixels[offset]) >> LUMINANCE_SHIFT]++;
}
blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
} else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
if (argument < 0 || argument >= height) {
throw new IllegalArgumentException("Row is not within the image: " + argument);
}
int offset = argument * width;
for (int x = 0; x < width; x++) {
histogram[computeRGBLuminance(rgbPixels[offset + x]) >> LUMINANCE_SHIFT]++;
}
} else {
throw new IllegalArgumentException("Unknown method: " + method);
}
} else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
// TODO
} else {
throw new IllegalArgumentException("Unknown method: " + method);
blackPoint = BlackPointEstimator.estimate(histogram) << LUMINANCE_SHIFT;
lastMethod = method;
lastArgument = argument;
}
lastMethod = method;
}
public BlackPointEstimationMethod getLastEstimationMethod() {

39
javase/src/com/google/zxing/client/j2se/BufferedImageMonochromeBitmapSource.java
View file

@ -35,10 +35,17 @@ public final class BufferedImageMonochromeBitmapSource implements MonochromeBitm
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) {
@ -69,26 +76,34 @@ public final class BufferedImageMonochromeBitmapSource implements MonochromeBitm
}
public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(lastMethod)) {
int width = image.getWidth();
int height = image.getHeight();
int[] luminanceBuckets = new int[32];
if (!method.equals(lastMethod) || argument != lastArgument) {
int width = image.getWidth();
int height = image.getHeight();
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.getRGB(startJ + n, startI + n);
luminanceBuckets[computeRGBLuminance(pixel) >> 3]++;
histogram[computeRGBLuminance(pixel) >> LUMINANCE_SHIFT]++;
}
blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
} else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
if (argument < 0 || argument >= height) {
throw new IllegalArgumentException("Row is not within the image: " + argument);
}
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);
}
} else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
// TODO
} else {
throw new IllegalArgumentException("Unknown method: " + method);
blackPoint = BlackPointEstimator.estimate(histogram) << LUMINANCE_SHIFT;
lastMethod = method;
lastArgument = argument;
}
lastMethod = method;
}
public BlackPointEstimationMethod getLastEstimationMethod() {

10
javase/src/com/google/zxing/client/j2se/CommandLineRunner.java
View file

@ -40,9 +40,11 @@ public final class CommandLineRunner {
File inputFile = new File(args[0]);
if (inputFile.exists()) {
if (inputFile.isDirectory()) {
int successful = 0;
for (File input : inputFile.listFiles()) {
decode(input.toURI());
if (decode(input.toURI())) successful++;
}
System.out.println("Decoded " + successful + " files successfully");
} else {
decode(inputFile.toURI());
}
@ -51,17 +53,19 @@ public final class CommandLineRunner {
}
}
private static void decode(URI uri) throws IOException {
private static boolean decode(URI uri) throws IOException {
BufferedImage image = ImageIO.read(uri.toURL());
if (image == null) {
System.err.println(uri.toString() + ": Could not load image");
return;
return false;
}
try {
String result = new MultiFormatReader().decode(new BufferedImageMonochromeBitmapSource(image)).getText();
System.out.println(uri.toString() + ": " + result);
return true;
} catch (ReaderException e) {
System.out.println(uri.toString() + ": No barcode found");
return false;
}
}