logPolar/linearPolar: more accurate processing near zero angle slice

modules/imgproc/src/imgwarp.cpp

@@ -50,6 +50,8 @@
 #include "precomp.hpp"
 #include "opencl_kernels_imgproc.hpp"
 
+using namespace cv;
+
 namespace cv
 {
 #if IPP_VERSION_X100 >= 710
@@ -6475,11 +6477,13 @@ CV_IMPL void
 cvLogPolar( const CvArr* srcarr, CvArr* dstarr,
             CvPoint2D32f center, double M, int flags )
 {
+    Mat src_with_border; // don't scope this variable (it holds image data)
+
     cv::Ptr<CvMat> mapx, mapy;
 
     CvMat srcstub, *src = cvGetMat(srcarr, &srcstub);
     CvMat dststub, *dst = cvGetMat(dstarr, &dststub);
-    CvSize ssize, dsize;
+    CvSize dsize;
 
     if( !CV_ARE_TYPES_EQ( src, dst ))
         CV_Error( CV_StsUnmatchedFormats, "" );
@@ -6487,7 +6491,6 @@ cvLogPolar( const CvArr* srcarr, CvArr* dstarr,
     if( M <= 0 )
         CV_Error( CV_StsOutOfRange, "M should be >0" );
 
-    ssize = cvGetMatSize(src);
     dsize = cvGetMatSize(dst);
 
     mapx.reset(cvCreateMat( dsize.height, dsize.width, CV_32F ));
@@ -6522,6 +6525,13 @@ cvLogPolar( const CvArr* srcarr, CvArr* dstarr,
     }
     else
     {
+        const int ANGLE_BORDER = 1;
+        Mat src_ = cv::cvarrToMat(src);
+        cv::copyMakeBorder(src_, src_with_border, ANGLE_BORDER, ANGLE_BORDER, 0, 0, BORDER_WRAP);
+        srcstub = src_with_border; src = &srcstub;
+        CvSize ssize = cvGetMatSize(src);
+        ssize.height -= 2*ANGLE_BORDER;
+
         int x, y;
         CvMat bufx, bufy, bufp, bufa;
         double ascale = ssize.height/(2*CV_PI);
@@ -6558,7 +6568,7 @@ cvLogPolar( const CvArr* srcarr, CvArr* dstarr,
                 double phi = bufa.data.fl[x]*ascale;
 
                 mx[x] = (float)rho;
-                my[x] = (float)phi;
+                my[x] = (float)phi + ANGLE_BORDER;
             }
 #else
             for( x = 0; x < dsize.width; x++ )
@@ -6599,11 +6609,13 @@ CV_IMPL
 void cvLinearPolar( const CvArr* srcarr, CvArr* dstarr,
             CvPoint2D32f center, double maxRadius, int flags )
 {
+    Mat src_with_border; // don't scope this variable (it holds image data)
+
     cv::Ptr<CvMat> mapx, mapy;
 
     CvMat srcstub, *src = (CvMat*)srcarr;
     CvMat dststub, *dst = (CvMat*)dstarr;
-    CvSize ssize, dsize;
+    CvSize dsize;
 
     src = cvGetMat( srcarr, &srcstub,0,0 );
     dst = cvGetMat( dstarr, &dststub,0,0 );
@@ -6611,10 +6623,7 @@ void cvLinearPolar( const CvArr* srcarr, CvArr* dstarr,
     if( !CV_ARE_TYPES_EQ( src, dst ))
         CV_Error( CV_StsUnmatchedFormats, "" );
 
-    ssize.width = src->cols;
-    ssize.height = src->rows;
-    dsize.width = dst->cols;
-    dsize.height = dst->rows;
+    dsize = cvGetMatSize(dst);
 
     mapx.reset(cvCreateMat( dsize.height, dsize.width, CV_32F ));
     mapy.reset(cvCreateMat( dsize.height, dsize.width, CV_32F ));
@@ -6643,6 +6652,13 @@ void cvLinearPolar( const CvArr* srcarr, CvArr* dstarr,
     }
     else
     {
+        const int ANGLE_BORDER = 1;
+        Mat src_ = cv::cvarrToMat(src);
+        cv::copyMakeBorder(src_, src_with_border, ANGLE_BORDER, ANGLE_BORDER, 0, 0, BORDER_WRAP);
+        srcstub = src_with_border; src = &srcstub;
+        CvSize ssize = cvGetMatSize(src);
+        ssize.height -= 2*ANGLE_BORDER;
+
         int x, y;
         CvMat bufx, bufy, bufp, bufa;
         const double ascale = ssize.height/(2*CV_PI);
@@ -6674,7 +6690,7 @@ void cvLinearPolar( const CvArr* srcarr, CvArr* dstarr,
                 double rho = bufp.data.fl[x]*pscale;
                 double phi = bufa.data.fl[x]*ascale;
                 mx[x] = (float)rho;
-                my[x] = (float)phi;
+                my[x] = (float)phi + ANGLE_BORDER;
             }
         }
     }