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Using a perspective transformation on CharAnalysis instead of redoing the whole process during segmentation. Much faster and seems slightly more accurate -- will need to benchmark.

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This commit is contained in:
Matt Hill
2014-10-19 19:07:00 -04:00
parent d2bfebe443
commit a691d8a6fe
4 changed files with 102 additions and 22 deletions
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86
src/openalpr/licenseplatecandidate.cpp
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@@ -17,6 +17,8 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <opencv2/core/core.hpp>
#include "licenseplatecandidate.h"
using namespace std;
@@ -67,14 +69,49 @@ void LicensePlateCandidate::recognize()
if (cornerFinder.confidence > 0)
{
cout << "Transforming" << endl;
Mat originalCrop = pipeline_data->crop_gray;
pipeline_data->plate_corners = transformPointsToOriginalImage(this->pipeline_data->grayImg, pipeline_data->crop_gray, expandedRegion, smallPlateCorners);
pipeline_data->crop_gray = deSkewPlate(this->pipeline_data->grayImg, pipeline_data->plate_corners);
Size outputImageSize = getOutputImageSize(pipeline_data->plate_corners);
Mat transmtx = getTransformationMatrix(pipeline_data->plate_corners, outputImageSize);
pipeline_data->crop_gray = deSkewPlate(this->pipeline_data->grayImg, outputImageSize, transmtx);
cout << "Size: " << outputImageSize.width << " - " << outputImageSize.height << endl;
// Apply a perspective transformation to the TextLine objects
// to match the newly deskewed license plate crop
vector<TextLine> newLines;
for (uint i = 0; i < pipeline_data->textLines.size(); i++)
{
vector<Point2f> textArea = transformPointsToOriginalImage(this->pipeline_data->grayImg, originalCrop, expandedRegion,
pipeline_data->textLines[i].textArea);
vector<Point2f> linePolygon = transformPointsToOriginalImage(this->pipeline_data->grayImg, originalCrop, expandedRegion,
pipeline_data->textLines[i].linePolygon);
vector<Point2f> textAreaRemapped;
vector<Point2f> linePolygonRemapped;
perspectiveTransform(textArea, textAreaRemapped, transmtx);
perspectiveTransform(linePolygon, linePolygonRemapped, transmtx);
newLines.push_back(TextLine(textAreaRemapped, linePolygonRemapped));
}
pipeline_data->textLines.clear();
for (uint i = 0; i < newLines.size(); i++)
pipeline_data->textLines.push_back(newLines[i]);
Mat debugImg = pipeline_data->textLines[0].drawDebugImage(pipeline_data->crop_gray);
drawAndWait(&debugImg);
charSegmenter = new CharacterSegmenter(pipeline_data);
//this->recognizedText = ocr->recognizedText;
//strcpy(this->recognizedText, ocr.recognizedText);
pipeline_data->plate_area_confidence = 100;
}
@@ -100,13 +137,9 @@ vector<Point2f> LicensePlateCandidate::transformPointsToOriginalImage(Mat bigIma
return cornerPoints;
}
Mat LicensePlateCandidate::deSkewPlate(Mat inputImage, vector<Point2f> corners)
Size LicensePlateCandidate::getOutputImageSize(vector<Point2f> corners)
{
timespec startTime;
getTime(&startTime);
// Figure out the appoximate width/height of the license plate region, so we can maintain the aspect ratio.
// Figure out the approximate width/height of the license plate region, so we can maintain the aspect ratio.
LineSegment leftEdge(round(corners[3].x), round(corners[3].y), round(corners[0].x), round(corners[0].y));
LineSegment rightEdge(round(corners[2].x), round(corners[2].y), round(corners[1].x), round(corners[1].y));
LineSegment topEdge(round(corners[0].x), round(corners[0].y), round(corners[1].x), round(corners[1].y));
@@ -115,7 +148,6 @@ Mat LicensePlateCandidate::deSkewPlate(Mat inputImage, vector<Point2f> corners)
float w = distanceBetweenPoints(leftEdge.midpoint(), rightEdge.midpoint());
float h = distanceBetweenPoints(bottomEdge.midpoint(), topEdge.midpoint());
float aspect = w/h;
int width = config->ocrImageWidthPx;
int height = round(((float) width) / aspect);
if (height > config->ocrImageHeightPx)
@@ -123,22 +155,37 @@ Mat LicensePlateCandidate::deSkewPlate(Mat inputImage, vector<Point2f> corners)
height = config->ocrImageHeightPx;
width = round(((float) height) * aspect);
}
return Size(width, height);
}
Mat deskewed(height, width, this->pipeline_data->grayImg.type());
Mat LicensePlateCandidate::getTransformationMatrix(vector<Point2f> corners, Size outputImageSize)
{
// Corners of the destination image
vector<Point2f> quad_pts;
quad_pts.push_back(Point2f(0, 0));
quad_pts.push_back(Point2f(deskewed.cols, 0));
quad_pts.push_back(Point2f(deskewed.cols, deskewed.rows));
quad_pts.push_back(Point2f(0, deskewed.rows));
quad_pts.push_back(Point2f(outputImageSize.width, 0));
quad_pts.push_back(Point2f(outputImageSize.width, outputImageSize.height));
quad_pts.push_back(Point2f(0, outputImageSize.height));
// Get transformation matrix
Mat transmtx = getPerspectiveTransform(corners, quad_pts);
// Apply perspective transformation
warpPerspective(inputImage, deskewed, transmtx, deskewed.size(), INTER_CUBIC);
return transmtx;
}
Mat LicensePlateCandidate::deSkewPlate(Mat inputImage, Size outputImageSize, Mat transformationMatrix)
{
timespec startTime;
getTime(&startTime);
Mat deskewed(outputImageSize, this->pipeline_data->grayImg.type());
// Apply perspective transformation to the image
warpPerspective(inputImage, deskewed, transformationMatrix, deskewed.size(), INTER_CUBIC);
if (config->debugTiming)
{
timespec endTime;
@@ -152,3 +199,8 @@ Mat LicensePlateCandidate::deSkewPlate(Mat inputImage, vector<Point2f> corners)
return deskewed;
}
//void LicensePlateCandidate::remapTextArea(cv::Mat inputImage, std::vector<cv::Point2f> corners) {
//
//}