Fix Single ThresholdBug in Simple Blob Detector#19859
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alalek merged 3 commits intoopencv:3.4from Apr 8, 2021
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cast type in comparison and remove docs address bug with using min dist between blobs in blob detector use scalar instead of int address bug with using min dist between blobs in blob detector
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danielenricocahall
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…ctor-single-thresh Fix Single ThresholdBug in Simple Blob Detector * address bug with using min dist between blobs in blob detector cast type in comparison and remove docs address bug with using min dist between blobs in blob detector use scalar instead of int address bug with using min dist between blobs in blob detector * fix namespace and formatting
alalek
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Oct 5, 2021
| // if the difference between min and max threshold is less than the threshold step | ||
| // we're only going to enter the loop once, so we need to add curCenters | ||
| // to ensure we still use minDistBetweenBlobs | ||
| centers.push_back(curCenters); |
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alalek
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Oct 6, 2021
| SimpleBlobDetector::Params params; | ||
| params.minThreshold = 250; | ||
| params.maxThreshold = 260; | ||
| std::vector<KeyPoint> keypoints; |
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params.minRepeatability = 2 by default.
This is why no keypoints are detected here if there is one "threshold" only (which parameters combination doesn't makes sense).
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Per the bug mentioned in #6667, if there is only one threshold, the logic which uses
minDistBetweenBlobsis not reached. This PR addresses that issue by ensuring that, if there is only one threshold, we addcurCentersbefore the blob distance checking logic. The test replicates the test setup described in the issue, which originally failed but now passes, ascentersis now populated and therefore we extract keypoints.Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
Patch to opencv_extra has the same branch name.