imgproc: add minEnclosingConvexPolygon #27369
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OpenCV already proposes:
What is the use case of the new function that is not covered in OpenCV? |
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Discussed the solution on the core team meeting. Please go ahead with the PR. |
asmorkalov
reviewed
Jun 18, 2025
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| @note Currently, the Otsu's method is implemented only for CV_8UC1 and CV_16UC1 images, | ||
| and the Triangle's method is implemented only for CV_8UC1 images. | ||
| @note Currently, the Otsu's and Triangle methods are implemented only for 8-bit single-channel images. | ||
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| @param src input array (multiple-channel, CV_8U, CV_16S, CV_16U, CV_32F or CV_64F). | ||
| @param src input array (multiple-channel, 8-bit or 32-bit floating point). | ||
| @param dst output array of the same size and type and the same number of channels as src. | ||
| @param thresh threshold value. | ||
| @param maxval maximum value to use with the #THRESH_BINARY and #THRESH_BINARY_INV thresholding | ||
| types. | ||
| @param type thresholding type (see #ThresholdTypes). | ||
| @return the computed threshold value if Otsu's or Triangle methods used. | ||
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| @sa thresholdWithMask, adaptiveThreshold, findContours, compare, min, max | ||
| @sa adaptiveThreshold, findContours, compare, min, max | ||
| */ | ||
| CV_EXPORTS_W double threshold( InputArray src, OutputArray dst, | ||
| double thresh, double maxval, int type ); | ||
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| /** @brief Same as #threshold, but with an optional mask | ||
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| @note If the mask is empty, #thresholdWithMask is equivalent to #threshold. | ||
| If the mask is not empty, dst *must* be of the same size and type as src, so that | ||
| outliers pixels are left as-is | ||
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| @param src input array (multiple-channel, 8-bit or 32-bit floating point). | ||
| @param dst output array of the same size and type and the same number of channels as src. | ||
| @param mask optional mask (same size as src, 8-bit). | ||
| @param thresh threshold value. | ||
| @param maxval maximum value to use with the #THRESH_BINARY and #THRESH_BINARY_INV thresholding | ||
| types. | ||
| @param type thresholding type (see #ThresholdTypes). | ||
| @return the computed threshold value if Otsu's or Triangle methods used. | ||
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| @sa threshold, adaptiveThreshold, findContours, compare, min, max | ||
| */ | ||
| CV_EXPORTS_W double thresholdWithMask( InputArray src, InputOutputArray dst, InputArray mask, | ||
| double thresh, double maxval, int type ); |
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The changes are not relevant. Looks like you need to rebase on top of 4.x and properly fix conflicts.
| @@ -4173,9 +4149,7 @@ CV_EXPORTS_W RotatedRect minAreaRect( InputArray points ); | |||
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| /** @brief Finds the four vertices of a rotated rect. Useful to draw the rotated rectangle. | |||
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| The function finds the four vertices of a rotated rectangle. The four vertices are returned | |||
| in clockwise order starting from the point with greatest \f$y\f$. If two points have the | |||
| same \f$y\f$ coordinate the rightmost is the starting point. This function is useful to draw the | |||
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| // | ||
| // | ||
| // | ||
| // License Agreement | ||
| // For Open Source Computer Vision Library | ||
| // | ||
| // Copyright (C) 2000, Intel Corporation, all rights reserved. | ||
| // Copyright (C) 2013, OpenCV Foundation, all rights reserved. | ||
| // Copyright (C) 2020, Sara Kuhnert, all rights reserved. | ||
| // Third party copyrights are property of their respective owners. | ||
| // | ||
| // Redistribution and use in source and binary forms, with or without modification, | ||
| // are permitted provided that the following conditions are met: | ||
| // | ||
| // * Redistribution's of source code must retain the above copyright notice, | ||
| // this list of conditions and the following disclaimer. | ||
| // | ||
| // * Redistribution's in binary form must reproduce the above copyright notice, | ||
| // this list of conditions and the following disclaimer in the documentation | ||
| // and/or other materials provided with the distribution. | ||
| // | ||
| // * The name of the copyright holders may not be used to endorse or promote products | ||
| // derived from this software without specific prior written permission. | ||
| // | ||
| // This software is provided by the copyright holders and contributors "as is" and | ||
| // any express or implied warranties, including, but not limited to, the implied | ||
| // warranties of merchantability and fitness for a particular purpose are disclaimed. | ||
| // In no event shall the Intel Corporation or contributors be liable for any direct, | ||
| // indirect, incidental, special, exemplary, or consequential damages | ||
| // (including, but not limited to, procurement of substitute goods or services; | ||
| // loss of use, data, or profits; or business interruption) however caused | ||
| // and on any theory of liability, whether in contract, strict liability, | ||
| // or tort (including negligence or otherwise) arising in any way out of | ||
| // the use of this software, even if advised of the possibility of such damage. | ||
| // | ||
| //M*/ |
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Please remove old copyright headers and use only the new one (top 5 lines).
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| static void findMinEnclosingPolygon(cv::InputArray points, | ||
| const int &k, | ||
| CV_OUT cv::OutputArray &kgon, | ||
| CV_OUT double &area); |
There was a problem hiding this comment.
CV_OUT macro is not needed in the implementation.
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| try | ||
| { | ||
| if (ngon.size() < 3) | ||
| { | ||
| throw std::invalid_argument( | ||
| "ngon must have 3 or more different points enclosing an area" ); | ||
| } | ||
| if (cv::contourArea(ngon) < EPSILON ) | ||
| { | ||
| throw std::invalid_argument( "invalid ngon: all points on line" ); | ||
| } | ||
| if (k <= 3) | ||
| { | ||
| throw std::invalid_argument( "k must be 3 or higher" ); | ||
| } | ||
| const size_t n = ngon.size(); | ||
| if ((const int)n == k) | ||
| { | ||
| throw std::runtime_error ("(n = k)"); | ||
| } | ||
| if ((const int)n < k) | ||
| { | ||
| throw std::runtime_error ("(n < k)"); | ||
| } | ||
| } | ||
| catch (std::invalid_argument &message) | ||
| { | ||
| std::cout << "invalid argument: " << message.what() << std::endl; | ||
| return; | ||
| } | ||
| catch (std::runtime_error &message) | ||
| { | ||
| std::cout << "Warning: no minimum area polygon calculated " << message.what() << std::endl; | ||
| cv::Mat(ngon).copyTo(minPolygon); | ||
| area = cv::contourArea(minPolygon); | ||
| return; | ||
| } | ||
| catch (...) | ||
| { | ||
| std::cout << "input error" << std::endl; | ||
| return; | ||
| } | ||
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| try | ||
| { | ||
| std::vector<cv::Point2f> kgon; | ||
| findMinAreaPolygon(ngon, kgon, area, k); | ||
| cv::Mat(kgon).copyTo(minPolygon); | ||
| } | ||
| catch (...) | ||
| { | ||
| std::cout << "correct input but execution failed" << std::endl; | ||
| return; | ||
| } |
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Please do not use try-catch. OpenCV uses CV_Assert, CV_Check for the function input validation and and CV_LOG_DEBUG/CV_LOG_INFO for notifications. Function should not silently ignore obvious invalid inputs like not enough points or wrong data types and ranges.
| } | ||
| else | ||
| { | ||
| throw std::logic_error(""); |
There was a problem hiding this comment.
OpenCV uses CV_Assert for such purposes.
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| if(h == 0) | ||
| { | ||
| throw std::logic_error(""); | ||
| } |
There was a problem hiding this comment.
OpenCV uses CV_Assert for such purposes.
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| area = cv::contourArea(minPolygon); | ||
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| return; |
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It makes sense to return area rather use double& parameter.
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Friendly reminder. |
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Patch to opencv_extra has the same branch name.