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Improved datamatrix reader with new algorithm

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git-svn-id: https://zxing.googlecode.com/svn/trunk@1574 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
dav.olivier@gmail.com 2010-09-03 20:49:22 +00:00
parent 47d2f3c798
commit a573e789d2
4 changed files with 110 additions and 164 deletions
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181
core/src/com/google/zxing/common/detector/WhiteRectangleDetector.java
View file

@ -33,7 +33,6 @@ import com.google.zxing.common.BitMatrix;
public final class WhiteRectangleDetector {
private static final int INIT_SIZE = 40;
private static final int MIN_SIZE = 20;
private final BitMatrix image;
private final int height;
@ -134,35 +133,92 @@ public final class WhiteRectangleDetector {
if (!sizeExceeded && atLeastOneBlackPointFoundOnBorder) {
// t t
//z x
// x OR z
// y y
ResultPoint x=null, y=null, z=null, t=null;
ResultPoint x = getBlackPoint(up, down, right - 1, false);
ResultPoint y = getBlackPoint(left, right, down - 1, true);
ResultPoint z = getBlackPoint(up, down, left + 1, false);
ResultPoint t = getBlackPoint(left, right, up + 1, true);
final int max_size = right-left;
// if the rectangle if perfectly horizontal (mostly in test cases)
// then we end up with:
// zt x
//
// y
for (int i = 1; i < max_size; i++){
ResultPoint a = new ResultPoint(left, down-i);
ResultPoint b = new ResultPoint(left+i, down);
z = getBlackPointOnSegment(a, b);
if (z != null){
break;
}
}
if (distance(z, t) < MIN_SIZE) {
ResultPoint u = getBlackPointInverted(up, down, right - 1, false);
t = x;
x = u;
}
if (z == null){
throw NotFoundException.getNotFoundInstance();
}
return centerEdges(y, z, x, t);
//go down right
for (int i = 1; i < max_size; i++){
ResultPoint a = new ResultPoint(left, up+i);
ResultPoint b = new ResultPoint(left+i, up);
t = getBlackPointOnSegment(a, b);
if (t != null){
break;
}
}
if (t == null){
throw NotFoundException.getNotFoundInstance();
}
//go down left
for (int i = 1; i < max_size; i++){
ResultPoint a = new ResultPoint(right, up+i);
ResultPoint b = new ResultPoint(right-i, up);
x = getBlackPointOnSegment(a, b);
if (x != null){
break;
}
}
if (x == null){
throw NotFoundException.getNotFoundInstance();
}
//go up left
for (int i = 1; i < max_size; i++){
ResultPoint a = new ResultPoint(right, down-i);
ResultPoint b = new ResultPoint(right-i, down);
y = getBlackPointOnSegment(a, b);
if (y != null){
break;
}
}
if (y == null){
throw NotFoundException.getNotFoundInstance();
}
return centerEdges(y, z, x, t);
} else {
throw NotFoundException.getNotFoundInstance();
throw NotFoundException.getNotFoundInstance();
}
}
private ResultPoint getBlackPointOnSegment(ResultPoint a, ResultPoint b) {
int dist = distanceL2(a, b);
float xStep = (b.getX()-a.getX())/dist;
float yStep = (b.getY()-a.getY())/dist;
for (int i = 0; i < dist; i++){
if (image.get(Math.round(a.getX()+i*xStep), Math.round(a.getY()+i*yStep))){
return new ResultPoint(Math.round(a.getX()+i*xStep), Math.round(a.getY()+i*yStep));
}
}
return null;
}
private static int distanceL2(ResultPoint a, ResultPoint b) {
return (int) Math.round(Math.sqrt((a.getX() - b.getX())
* (a.getX() - b.getX()) + (a.getY() - b.getY())
* (a.getY() - b.getY())));
}
/**
* recenters the points of a constant distance towards the center
*
@ -203,89 +259,6 @@ public final class WhiteRectangleDetector {
}
}
// L1 distance (metropolitan distance)
private static float distance(ResultPoint a, ResultPoint b) {
return Math.abs(a.getX() - b.getX()) + Math.abs(a.getY() - b.getY());
}
/**
* Gets the coordinate of an extreme black point of a segment
*
* @param a min value of the scanned coordinate
* @param b max value of the scanned coordinate
* @param fixed value of fixed coordinate
* @param horizontal set to true if scan must be horizontal, false if vertical
* @return {@link ResultPoint} describing the black point. If scan is horizontal,
* the returned point is the first encountered if it is on the left of the image,
* else the last one. If scan is vertical, the returned point is the first encountered
* if it is on the top of the image, else the last one.
* {@link ResultPoint} is null if not black point has been found
*/
private ResultPoint getBlackPoint(int a, int b, int fixed, boolean horizontal) {
ResultPoint last = null;
if (horizontal) {
for (int x = a; x < b; x++) {
if (image.get(x, fixed)) {
if (x < width / 2) {
return new ResultPoint(x, fixed);
} else {
while (x < width && image.get(x, fixed)) {
x++;
}
x--;
last = new ResultPoint(x, fixed);
}
}
}
} else {
for (int y = a; y < b; y++) {
if (image.get(fixed, y)) {
if (y < height / 2) {
return new ResultPoint(fixed, y);
} else {
while (y < height && image.get(fixed, y)) {
y++;
}
y--;
last = new ResultPoint(fixed, y);
}
}
}
}
return last;
}
/**
* Same as getBlackPoint, but returned point is the last one found.
*
* @param a min value of the scanned coordinate
* @param b max value of the scanned coordinate
* @param fixed value of fixed coordinate
* @param horizontal set to true if scan must be horizontal, false if vertical
* @return {@link ResultPoint} describing the black point.
*/
private ResultPoint getBlackPointInverted(int a, int b, int fixed, boolean horizontal) {
if (horizontal) {
for (int x = b + 1; x >= a; x--) {
if (image.get(x, fixed)) {
return new ResultPoint(x, fixed);
}
}
} else {
for (int y = b + 1; y >= a; y--) {
if (image.get(fixed, y)) {
return new ResultPoint(fixed, y);
}
}
}
return null;
}
/**
* Determines whether a segment contains a black point
*

73
core/src/com/google/zxing/datamatrix/detector/Detector.java
View file

@ -37,8 +37,6 @@ import java.util.Vector;
*/
public final class Detector {
private static final int MIN_GIVEUP_THRESHOLD = 3;
// Trick to avoid creating new Integer objects below -- a sort of crude copy of
// the Integer.valueOf(int) optimization added in Java 5, not in J2ME
private static final Integer[] INTEGERS =
@ -82,12 +80,6 @@ public final class Detector {
ResultPointsAndTransitions lSideOne = (ResultPointsAndTransitions) transitions.elementAt(0);
ResultPointsAndTransitions lSideTwo = (ResultPointsAndTransitions) transitions.elementAt(1);
//give up if there is no chance we'll decode something...
if (lSideOne.transitions > MIN_GIVEUP_THRESHOLD ||
lSideTwo.transitions > MIN_GIVEUP_THRESHOLD) {
throw NotFoundException.getNotFoundInstance();
}
// Figure out which point is their intersection by tallying up the number of times we see the
// endpoints in the four endpoints. One will show up twice.
Hashtable pointCount = new Hashtable();
@ -149,7 +141,7 @@ public final class Detector {
// The top right point is actually the corner of a module, which is one of the two black modules
// adjacent to the white module at the top right. Tracing to that corner from either the top left
// or bottom right should work here.
int dimension = Math.max(transitionsBetween(topLeft, topRight).getTransitions(),
int dimension = Math.min(transitionsBetween(topLeft, topRight).getTransitions(),
transitionsBetween(bottomRight, topRight).getTransitions());
if ((dimension & 0x01) == 1) {
// it can't be odd, so, round... up?
@ -161,7 +153,7 @@ public final class Detector {
ResultPoint correctedTopRight = correctTopRight(bottomLeft, bottomRight, topLeft, topRight, dimension);
//We redetermine the dimension using the corrected top right point
int dimension2 = Math.min(transitionsBetween(topLeft, correctedTopRight).getTransitions(),
int dimension2 = Math.max(transitionsBetween(topLeft, correctedTopRight).getTransitions(),
transitionsBetween(bottomRight, correctedTopRight).getTransitions());
dimension2++;
if ((dimension2 & 0x01) == 1) {
@ -181,48 +173,29 @@ public final class Detector {
ResultPoint topLeft,
ResultPoint topRight,
int dimension) {
float corr = distance(bottomLeft, bottomRight) / (float) dimension;
float corrx = 0.0f;
float corry = 0.0f;
int norm = distance(topLeft, topRight);
float cos = (topRight.getX() - topLeft.getX()) / norm;
float sin = -(topRight.getY() - topLeft.getY()) / norm;
if (cos > 0.0f && sin > 0.0f) {
if (cos > sin) {
corrx = corr * cos;
corry = -corr * sin;
} else {
corrx = -corr * sin;
corry = -corr * cos;
}
} else if (cos > 0.0f && sin < 0.0f) {
if (cos > -sin) {
corrx = -corr * sin;
corry = -corr * cos;
} else {
corrx = corr * cos;
corry = -corr * sin;
}
} else if (cos < 0.0f && sin < 0.0f) {
if (-cos > -sin) {
corrx = corr * cos;
corry = -corr * sin;
} else {
corrx = -corr * sin;
corry = -corr * cos;
}
} else if (cos < 0.0f && sin > 0.0f) {
if (-cos > sin) {
corrx = -corr * sin;
corry = -corr * cos;
} else {
corrx = corr * cos;
corry = -corr * sin;
}
}
float corr = distance(bottomLeft, bottomRight) / (float)dimension;
int norm = distance(topLeft, topRight);
float cos = (topRight.getX() - topLeft.getX()) / norm;
float sin = (topRight.getY() - topLeft.getY()) / norm;
return new ResultPoint(topRight.getX() + corrx, topRight.getY() + corry);
ResultPoint c1 = new ResultPoint(topRight.getX()+corr*cos, topRight.getY()+corr*sin);
corr = distance(bottomLeft, bottomRight) / (float)dimension;
norm = distance(bottomRight, topRight);
cos = (topRight.getX() - bottomRight.getX()) / norm;
sin = (topRight.getY() - bottomRight.getY()) / norm;
ResultPoint c2 = new ResultPoint(topRight.getX()+corr*cos, topRight.getY()+corr*sin);
int l1 = Math.abs(transitionsBetween(topLeft, c1).getTransitions() - transitionsBetween(bottomRight, c1).getTransitions());
int l2 = Math.abs(transitionsBetween(topLeft, c2).getTransitions() - transitionsBetween(bottomRight, c2).getTransitions());
if (l1 <= l2){
return c1;
}
return c2;
}
// L2 distance

6
core/test/src/com/google/zxing/datamatrix/DataMatrixBlackBox1TestCase.java
View file

@ -28,9 +28,9 @@ public final class DataMatrixBlackBox1TestCase extends AbstractBlackBoxTestCase
// TODO use MultiFormatReader here once Data Matrix decoder is done
super("test/data/blackbox/datamatrix-1", new DataMatrixReader(), BarcodeFormat.DATA_MATRIX);
addTest(7, 7, 0.0f);
addTest(4, 4, 90.0f);
addTest(6, 6, 180.0f);
addTest(6, 6, 270.0f);
addTest(7, 7, 90.0f);
addTest(7, 7, 180.0f);
addTest(7, 7, 270.0f);
}
}

8
core/test/src/com/google/zxing/datamatrix/DataMatrixBlackBox2TestCase.java
View file

@ -27,10 +27,10 @@ public final class DataMatrixBlackBox2TestCase extends AbstractBlackBoxTestCase
public DataMatrixBlackBox2TestCase() {
// TODO use MultiFormatReader here once Data Matrix decoder is done
super("test/data/blackbox/datamatrix-2", new DataMatrixReader(), BarcodeFormat.DATA_MATRIX);
addTest(5, 5, 0.0f);
addTest(6, 6, 90.0f);
addTest(7, 7, 180.0f);
addTest(7, 7, 270.0f);
addTest(10, 10, 0.0f);
addTest(13, 13, 90.0f);
addTest(16, 16, 180.0f);
addTest(12, 12, 270.0f);
}
}