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Using median character width (rather than max) to segment character blocks

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Matt Hill
2014-01-29 19:05:14 -06:00
parent 1afc1ff1eb
commit 7c54bfd77c
1 changed files with 37 additions and 10 deletions
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43
src/openalpr/charactersegmenter.cpp
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@@ -170,14 +170,16 @@ CharacterSegmenter::CharacterSegmenter(Mat img, bool invertedColors, Config* con
} }
float biggestCharWidth = avgCharWidth; float medianCharWidth = avgCharWidth;
vector<int> widthValues;
// Compute largest char width // Compute largest char width
for (int i = 0; i < allBoxes.size(); i++) for (int i = 0; i < allBoxes.size(); i++)
{ {
if (allBoxes[i].width > biggestCharWidth) widthValues.push_back(allBoxes[i].width);
biggestCharWidth = allBoxes[i].width;
} }
medianCharWidth = median(widthValues.data(), widthValues.size());
if (config->debugTiming) if (config->debugTiming)
{ {
@@ -187,7 +189,7 @@ CharacterSegmenter::CharacterSegmenter(Mat img, bool invertedColors, Config* con
} }
//ColorFilter colorFilter(img, charAnalysis->getCharacterMask()); //ColorFilter colorFilter(img, charAnalysis->getCharacterMask());
vector<Rect> candidateBoxes = getBestCharBoxes(charAnalysis->thresholds[0], allBoxes, biggestCharWidth); vector<Rect> candidateBoxes = getBestCharBoxes(charAnalysis->thresholds[0], allBoxes, medianCharWidth);
if (this->config->debugCharSegmenter) if (this->config->debugCharSegmenter)
@@ -210,11 +212,11 @@ CharacterSegmenter::CharacterSegmenter(Mat img, bool invertedColors, Config* con
getTime(&startTime); getTime(&startTime);
filterEdgeBoxes(charAnalysis->thresholds, candidateBoxes, biggestCharWidth, avgCharHeight); filterEdgeBoxes(charAnalysis->thresholds, candidateBoxes, medianCharWidth, avgCharHeight);
candidateBoxes = filterMostlyEmptyBoxes(charAnalysis->thresholds, candidateBoxes); candidateBoxes = filterMostlyEmptyBoxes(charAnalysis->thresholds, candidateBoxes);
candidateBoxes = combineCloseBoxes(candidateBoxes, biggestCharWidth); candidateBoxes = combineCloseBoxes(candidateBoxes, medianCharWidth);
cleanCharRegions(charAnalysis->thresholds, candidateBoxes); cleanCharRegions(charAnalysis->thresholds, candidateBoxes);
cleanMostlyFullBoxes(charAnalysis->thresholds, candidateBoxes); cleanMostlyFullBoxes(charAnalysis->thresholds, candidateBoxes);
@@ -310,14 +312,12 @@ vector<Rect> CharacterSegmenter::getHistogramBoxes(VerticalHistogram histogram,
if (maxHeightChar1 > MIN_HISTOGRAM_HEIGHT && minHeight < (0.25 * ((float) maxHeightChar1))) if (maxHeightChar1 > MIN_HISTOGRAM_HEIGHT && minHeight < (0.25 * ((float) maxHeightChar1)))
{ {
cout << "GOODY GOODY LEFT" << endl;
// Add a box for Char1 // Add a box for Char1
Point botRight = Point(minX - 1, allBoxes[i].y + allBoxes[i].height); Point botRight = Point(minX - 1, allBoxes[i].y + allBoxes[i].height);
charBoxes.push_back(Rect(allBoxes[i].tl(), botRight) ); charBoxes.push_back(Rect(allBoxes[i].tl(), botRight) );
} }
if (maxHeightChar2 > MIN_HISTOGRAM_HEIGHT && minHeight < (0.25 * ((float) maxHeightChar2))) if (maxHeightChar2 > MIN_HISTOGRAM_HEIGHT && minHeight < (0.25 * ((float) maxHeightChar2)))
{ {
cout << "GOODY GOODY RIGHT" << endl;
// Add a box for Char2 // Add a box for Char2
Point topLeft = Point(minX + 1, allBoxes[i].y); Point topLeft = Point(minX + 1, allBoxes[i].y);
charBoxes.push_back(Rect(topLeft, allBoxes[i].br()) ); charBoxes.push_back(Rect(topLeft, allBoxes[i].br()) );
@@ -360,6 +360,7 @@ vector<Rect> CharacterSegmenter::getBestCharBoxes(Mat img, vector<Rect> charBoxe
histoImg.at<uchar>(histoImg.rows - columnCount, col) = 255; histoImg.at<uchar>(histoImg.rows - columnCount, col) = 255;
} }
VerticalHistogram histogram(histoImg, Mat::ones(histoImg.size(), CV_8U));
// Go through each row in the histoImg and score it. Try to find the single line that gives me the most right-sized character regions (based on avgCharWidth) // Go through each row in the histoImg and score it. Try to find the single line that gives me the most right-sized character regions (based on avgCharWidth)
@@ -395,7 +396,33 @@ vector<Rect> CharacterSegmenter::getBestCharBoxes(Mat img, vector<Rect> charBoxe
validBoxes.push_back(allBoxes[boxidx]); validBoxes.push_back(allBoxes[boxidx]);
} }
else if (w > avgCharWidth * 2 && w <= MAX_SEGMENT_WIDTH * 2 )
{
// Try to split up doubles into two good char regions, check for a break between 40% and 60%
int leftEdge = allBoxes[boxidx].x + (int) (((float) allBoxes[boxidx].width) * 0.4f);
int rightEdge = allBoxes[boxidx].x + (int) (((float) allBoxes[boxidx].width) * 0.6f);
int minX = histogram.getLocalMinimum(leftEdge, rightEdge);
int maxXChar1 = histogram.getLocalMaximum(allBoxes[boxidx].x, minX);
int maxXChar2 = histogram.getLocalMaximum(minX, allBoxes[boxidx].x + allBoxes[boxidx].width);
int minHeight = histogram.getHeightAt(minX);
int maxHeightChar1 = histogram.getHeightAt(maxXChar1);
int maxHeightChar2 = histogram.getHeightAt(maxXChar2);
if ( minHeight < (0.25 * ((float) maxHeightChar1)))
{
// Add a box for Char1
Point botRight = Point(minX - 1, allBoxes[boxidx].y + allBoxes[boxidx].height);
validBoxes.push_back(Rect(allBoxes[boxidx].tl(), botRight) );
}
if ( minHeight < (0.25 * ((float) maxHeightChar2)))
{
// Add a box for Char2
Point topLeft = Point(minX + 1, allBoxes[boxidx].y);
validBoxes.push_back(Rect(topLeft, allBoxes[boxidx].br()) );
}
}
} }