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Issue 508

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git-svn-id: https://zxing.googlecode.com/svn/trunk@1523 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen 2010-08-12 20:24:38 +00:00
parent 6c9812e9bb
commit 0a6cac9820
3 changed files with 60 additions and 17 deletions
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39
core/src/com/google/zxing/common/HybridBinarizer.java
View file

@ -69,11 +69,17 @@ public final class HybridBinarizer extends GlobalHistogramBinarizer {
int width = source.getWidth();
int height = source.getHeight();
int subWidth = width >> 3;
if ((width & 0x07) != 0) {
subWidth++;
}
int subHeight = height >> 3;
int[][] blackPoints = calculateBlackPoints(luminances, subWidth, subHeight, width);
if ((height & 0x07) != 0) {
subHeight++;
}
int[][] blackPoints = calculateBlackPoints(luminances, subWidth, subHeight, width, height);
matrix = new BitMatrix(width, height);
calculateThresholdForBlock(luminances, subWidth, subHeight, width, blackPoints, matrix);
calculateThresholdForBlock(luminances, subWidth, subHeight, width, height, blackPoints, matrix);
} else {
// If the image is too small, fall back to the global histogram approach.
matrix = super.getBlackMatrix();
@ -82,13 +88,20 @@ public final class HybridBinarizer extends GlobalHistogramBinarizer {
}
// For each 8x8 block in the image, calculate the average black point using a 5x5 grid
// of the blocks around it. Also handles the corner cases, but will ignore up to 7 pixels
// on the right edge and 7 pixels at the bottom of the image if the overall dimensions are not
// multiples of eight. In practice, leaving those pixels white does not seem to be a problem.
// of the blocks around it. Also handles the corner cases (fractional blocks are computed based
// on the last 8 pixels in the row/column which are also used in the previous block).
private static void calculateThresholdForBlock(byte[] luminances, int subWidth, int subHeight,
int stride, int[][] blackPoints, BitMatrix matrix) {
int width, int height, int[][] blackPoints, BitMatrix matrix) {
for (int y = 0; y < subHeight; y++) {
int yoffset = y << 3;
if ((yoffset + 8) >= height) {
yoffset = height - 8;
}
for (int x = 0; x < subWidth; x++) {
int xoffset = x << 3;
if ((xoffset + 8) >= width) {
xoffset = width - 8;
}
int left = (x > 1) ? x : 2;
left = (left < subWidth - 2) ? left : subWidth - 3;
int top = (y > 1) ? y : 2;
@ -103,7 +116,7 @@ public final class HybridBinarizer extends GlobalHistogramBinarizer {
sum += blackRow[left + 2];
}
int average = sum / 25;
threshold8x8Block(luminances, x << 3, y << 3, average, stride, matrix);
threshold8x8Block(luminances, xoffset, yoffset, average, width, matrix);
}
}
}
@ -124,15 +137,23 @@ public final class HybridBinarizer extends GlobalHistogramBinarizer {
// Calculates a single black point for each 8x8 block of pixels and saves it away.
private static int[][] calculateBlackPoints(byte[] luminances, int subWidth, int subHeight,
int stride) {
int width, int height) {
int[][] blackPoints = new int[subHeight][subWidth];
for (int y = 0; y < subHeight; y++) {
int yoffset = y << 3;
if ((yoffset + 8) >= height) {
yoffset = height - 8;
}
for (int x = 0; x < subWidth; x++) {
int xoffset = x << 3;
if ((xoffset + 8) >= width) {
xoffset = width - 8;
}
int sum = 0;
int min = 255;
int max = 0;
for (int yy = 0; yy < 8; yy++) {
int offset = ((y << 3) + yy) * stride + (x << 3);
int offset = (yoffset + yy) * width + xoffset;
for (int xx = 0; xx < 8; xx++) {
int pixel = luminances[offset + xx] & 0xff;
sum += pixel;

34
cpp/core/src/zxing/common/HybridBinarizer.cpp
View file

@ -56,10 +56,16 @@ void HybridBinarizer::binarizeEntireImage() {
int width = source->getWidth();
int height = source->getHeight();
int subWidth = width >> 3;
if (width & 0x07) {
subWidth++;
}
int subHeight = height >> 3;
int *blackPoints = calculateBlackPoints(luminances, subWidth, subHeight, width);
if (height & 0x07) {
subHeight++;
}
int *blackPoints = calculateBlackPoints(luminances, subWidth, subHeight, width, height);
cached_matrix_.reset(new BitMatrix(width,height));
calculateThresholdForBlock(luminances, subWidth, subHeight, width, blackPoints, cached_matrix_);
calculateThresholdForBlock(luminances, subWidth, subHeight, width, height, blackPoints, cached_matrix_);
delete [] blackPoints;
delete [] luminances;
} else {
@ -70,9 +76,17 @@ void HybridBinarizer::binarizeEntireImage() {
}
void HybridBinarizer::calculateThresholdForBlock(unsigned char* luminances, int subWidth, int subHeight,
int stride, int blackPoints[], Ref<BitMatrix> matrix) {
int width, int height, int blackPoints[], Ref<BitMatrix> matrix) {
for (int y = 0; y < subHeight; y++) {
int yoffset = y << 3;
if (yoffset + 8 >= height) {
yoffset = height - 8;
}
for (int x = 0; x < subWidth; x++) {
int xoffset = x << 3;
if (xoffset + 8 >= width) {
xoffset = width - 8;
}
int left = (x > 1) ? x : 2;
left = (left < subWidth - 2) ? left : subWidth - 3;
int top = (y > 1) ? y : 2;
@ -87,7 +101,7 @@ void HybridBinarizer::calculateThresholdForBlock(unsigned char* luminances, int
sum += blackRow[left + 2];
}
int average = sum / 25;
threshold8x8Block(luminances, x << 3, y << 3, average, stride, matrix);
threshold8x8Block(luminances, xoffset, yoffset, average, width, matrix);
}
}
}
@ -106,15 +120,23 @@ void HybridBinarizer::threshold8x8Block(unsigned char* luminances, int xoffset,
}
int* HybridBinarizer::calculateBlackPoints(unsigned char* luminances, int subWidth, int subHeight,
int stride) {
int width, int height) {
int *blackPoints = new int[subHeight * subWidth];
for (int y = 0; y < subHeight; y++) {
int yoffset = y << 3;
if (yoffset + 8 >= height) {
yoffset = height - 8;
}
for (int x = 0; x < subWidth; x++) {
int xoffset = x << 3;
if (xoffset + 8 >= width) {
xoffset = width - 8;
}
int sum = 0;
int min = 255;
int max = 0;
for (int yy = 0; yy < 8; yy++) {
int offset = ((y << 3) + yy) * stride + (x << 3);
int offset = (yoffset + yy) * width + xoffset;
for (int xx = 0; xx < 8; xx++) {
int pixel = luminances[offset + xx] & 0xff;
sum += pixel;

4
cpp/core/src/zxing/common/HybridBinarizer.h
View file

@ -43,9 +43,9 @@ namespace zxing {
void binarizeEntireImage();
// We'll be using one-D arrays because C++ can't dynamically allocate 2D arrays
int* calculateBlackPoints(unsigned char* luminances, int subWidth, int subHeight,
int stride);
int width, int height);
void calculateThresholdForBlock(unsigned char* luminances, int subWidth, int subHeight,
int stride, int blackPoints[], Ref<BitMatrix> matrix);
int width, int height, int blackPoints[], Ref<BitMatrix> matrix);
void threshold8x8Block(unsigned char* luminances, int xoffset, int yoffset, int threshold,
int stride, Ref<BitMatrix> matrix);
};