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Speed up adaptive threshold in findChessboardCorners #25177

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Merged
asmorkalov merged 3 commits into from
Mar 27, 2024
Merged

Speed up adaptive threshold in findChessboardCorners #25177

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67f8aac
Speed up adaptive threshold in findChessboardCorners
MaximSmolskiy Mar 7, 2024
57923ab
Got rid of extra cv::Mat allocations.
asmorkalov Mar 27, 2024
ba3fc90
Got rid of extra cv::Mat allocations and copies
Mar 27, 2024
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17 changes: 14 additions & 3 deletions modules/calib3d/src/calibinit.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -583,8 +583,10 @@ bool findChessboardCorners(InputArray image_, Size pattern_size,
}
//if flag CALIB_CB_ADAPTIVE_THRESH is not set it doesn't make sense to iterate over k
int max_k = useAdaptive ? 6 : 1;
Mat prev_thresh_img;
for (int k = 0; k < max_k && !found; k++)
{
int prev_block_size = -1;
for (int dilations = min_dilations; dilations <= max_dilations; dilations++)
{
// convert the input grayscale image to binary (black-n-white)
Expand All @@ -595,9 +597,18 @@ bool findChessboardCorners(InputArray image_, Size pattern_size,
: prev_sqr_size * 2);
block_size = block_size | 1;
// convert to binary
adaptiveThreshold( img, thresh_img, 255, ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, block_size, (k/2)*5 );
dilate( thresh_img, thresh_img, Mat(), Point(-1, -1), dilations );

if (block_size != prev_block_size)
{
adaptiveThreshold( img, thresh_img, 255, ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, block_size, (k/2)*5 );
dilate( thresh_img, thresh_img, Mat(), Point(-1, -1), dilations );
thresh_img.copyTo(prev_thresh_img);
}
else if (dilations > 0)
{
dilate( prev_thresh_img, prev_thresh_img, Mat(), Point(-1, -1), 1 );
prev_thresh_img.copyTo(thresh_img);
}
prev_block_size = block_size;
}
else
{
Expand Down