remove marker form thinningIteration and remove "if" from forEach

modules/ximgproc/src/thinning.cpp

@@ -92,69 +92,35 @@ static uint8_t lut_guo_iter1[] = {
     1, 1, 1, 1};
 
 // Applies a thinning iteration to a binary image
-static void thinningIteration(Mat img, int iter, int thinningType){
-    Mat marker = Mat::zeros(img.size(), CV_8UC1);
+static void thinningIteration(Mat &img, Mat &marker, const uint8_t* const lut) {
     int rows = img.rows;
     int cols = img.cols;
     marker.col(0).setTo(1);
     marker.col(cols - 1).setTo(1);
     marker.row(0).setTo(1);
     marker.row(rows - 1).setTo(1);
 
-    if(thinningType == THINNING_ZHANGSUEN){
-        marker.forEach<uchar>([=](uchar& value, const int postion[]) {
-            int i = postion[0];
-            int j = postion[1];
-            if (i == 0 || j == 0 || i == rows - 1 || j == cols - 1)
-                return;
-
-            auto ptr = img.ptr(i, j); // p1
-
-            uchar p2 = ptr[-cols];
-            uchar p3 = ptr[-cols + 1];
-            uchar p4 = ptr[1];
-            uchar p5 = ptr[cols + 1];
-            uchar p6 = ptr[cols];
-            uchar p7 = ptr[cols - 1];
-            uchar p8 = ptr[-1];
-            uchar p9 = ptr[-cols - 1];
-
-            int neighbors = p9 | (p2 << 1) | (p3 << 2) | (p4 << 3) | (p5 << 4) | (p6 << 5) | (p7 << 6) | (p8 << 7);
-
-            if (iter == 0)
-                value = lut_zhang_iter0[neighbors];
-            else
-                value = lut_zhang_iter1[neighbors];
-        });
-    }
-    if(thinningType == THINNING_GUOHALL){
-        marker.forEach<uchar>([=](uchar& value, const int postion[]) {
-            int i = postion[0];
-            int j = postion[1];
-            if (i == 0 || j == 0 || i == rows - 1 || j == cols - 1)
-                return;
-
-            auto ptr = img.ptr(i, j); // p1
-
-            uchar p2 = ptr[-cols];
-            uchar p3 = ptr[-cols + 1];
-            uchar p4 = ptr[1];
-            uchar p5 = ptr[cols + 1];
-            uchar p6 = ptr[cols];
-            uchar p7 = ptr[cols - 1];
-            uchar p8 = ptr[-1];
-            uchar p9 = ptr[-cols - 1];
-
-            int neighbors = p9 | (p2 << 1) | (p3 << 2) | (p4 << 3) | (p5 << 4) | (p6 << 5) | (p7 << 6) | (p8 << 7);
-
-            if (iter == 0)
-                value = lut_guo_iter0[neighbors];
-            else
-                value = lut_guo_iter1[neighbors];
-        });
-    }
+    marker.forEach<uchar>([=](uchar& value, const int postion[]) {
+        int i = postion[0];
+        int j = postion[1];
+        if (i == 0 || j == 0 || i == rows - 1 || j == cols - 1) { return; }
+
+        auto ptr = img.ptr(i, j); // p1
+        uchar p2 = ptr[-cols];
+        uchar p3 = ptr[-cols + 1];
+        uchar p4 = ptr[1];
+        uchar p5 = ptr[cols + 1];
+        uchar p6 = ptr[cols];
+        uchar p7 = ptr[cols - 1];
+        uchar p8 = ptr[-1];
+        uchar p9 = ptr[-cols - 1];
+
+        int neighbors = p9 | (p2 << 1) | (p3 << 2) | (p4 << 3) | (p5 << 4) | (p6 << 5) | (p7 << 6) | (p8 << 7);
+        value = lut[neighbors];
+    });
 
     img &= marker;
+    marker.setTo(0);
 }
 
 // Apply the thinning procedure to a given image
@@ -164,9 +130,12 @@ void thinning(InputArray input, OutputArray output, int thinningType){
     // Enforce the range of the input image to be in between 0 - 255
     processed /= 255;
     Mat prev = processed.clone();
+    Mat marker = Mat::zeros(processed.size(), CV_8UC1);
+    const auto lutIter0 = (thinningType == THINNING_GUOHALL) ? lut_guo_iter0 : lut_zhang_iter0;
+    const auto lutIter1 = (thinningType == THINNING_GUOHALL) ? lut_guo_iter1 : lut_zhang_iter1;
     do {
-        thinningIteration(processed, 0, thinningType);
-        thinningIteration(processed, 1, thinningType);
+        thinningIteration(processed, marker, lutIter0);
+        thinningIteration(processed, marker, lutIter1);
         const auto res = cv::norm(processed, prev, cv::NORM_L1);
         if (res <= 0) { break; }
         processed.copyTo(prev);