Merge pull request #24539 from LaurentBerger:blobrecttoimage

Add blobrecttoimage #24539

### Pull Request Readiness Checklist

resolves https://github.com/opencv/opencv/issues/14659

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work #14659
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/dnn/include/opencv2/dnn/dnn.hpp

@@ -1222,6 +1222,20 @@ CV__DNN_INLINE_NS_BEGIN
         CV_PROP_RW DataLayout datalayout; //!< Order of output dimensions. Choose DNN_LAYOUT_NCHW or DNN_LAYOUT_NHWC.
         CV_PROP_RW ImagePaddingMode paddingmode;   //!< Image padding mode. @see ImagePaddingMode.
         CV_PROP_RW Scalar borderValue;   //!< Value used in padding mode for padding.
+
+        /** @brief Get rectangle coordinates in original image system from rectangle in blob coordinates.
+         *  @param rBlob rect in blob coordinates.
+         *  @param size original input image size.
+         *  @returns rectangle in original image coordinates.
+         */
+        CV_WRAP Rect blobRectToImageRect(const Rect &rBlob, const Size &size);
+
+        /** @brief Get rectangle coordinates in original image system from rectangle in blob coordinates.
+         *  @param rBlob rect in blob coordinates.
+         *  @param rImg result rect in image coordinates.
+         *  @param size original input image size.
+         */
+        CV_WRAP void blobRectsToImageRects(const std::vector<Rect> &rBlob, CV_OUT std::vector<Rect>& rImg, const Size& size);
     };
 
     /** @brief Creates 4-dimensional blob from image with given params.