Use bicubic interp in DetectNetTransform layer

src/caffe/layers/detectnet_transform_layer.cpp

@@ -81,7 +81,14 @@ void DetectNetTransformationLayer<Dtype>::retrieveMeanImage(Size dimensions) {
 
   // resize, if dimensions were defined:
   if (dimensions.area() > 0) {
-    resize(data_mean_, data_mean_, dimensions, cv::INTER_CUBIC);
+    // Resize using bicubic interpolation and then clamp to [min, max]
+    double minval, maxval;
+    cv::minMaxLoc(data_mean_, &minval, &maxval);
+    cv::resize(data_mean_, data_mean_, dimensions, 0, 0, cv::INTER_CUBIC);
+    cv::threshold(data_mean_, data_mean_, maxval, 0, cv::THRESH_TRUNC);
+    data_mean_ *= -1;
+    cv::threshold(data_mean_, data_mean_, -minval, 0, cv::THRESH_TRUNC);
+    data_mean_ *= -1;
   }
   // scale from 0..255 to 0..1:
   data_mean_ /= Dtype(UINT8_MAX);
@@ -439,7 +446,14 @@ void DetectNetTransformationLayer<Dtype>::transform_scale(
     Dtype scale_x = (Dtype)size.width / img.cols;
     Dtype scale_y = (Dtype)size.height / img.rows;
 
-    resize(img, *img_temp, size, cv::INTER_CUBIC);
+    // Resize using bicubic interpolation and then clamp to [min, max]
+    double minval, maxval;
+    cv::minMaxLoc(img, &minval, &maxval);
+    cv::resize(img, *img_temp, size, 0, 0, cv::INTER_CUBIC);
+    cv::threshold(*img_temp, *img_temp, maxval, 0, cv::THRESH_TRUNC);
+    *img_temp *= -1;
+    cv::threshold(*img_temp, *img_temp, -minval, 0, cv::THRESH_TRUNC);
+    *img_temp *= -1;
 
     vector<BboxLabel > bboxList_aug;
     foreach_(BboxLabel label, bboxList) {  // for every bbox: