avfilter/vf_edgedetect: properly implement double_threshold()

Important part of this algorithm is the double threshold step: pixels
above "high" threshold being kept, pixels below "low" threshold dropped,
pixels in between (weak edges) are kept if they are neighboring "high"
pixels.

The weak edge check uses a neighboring context and should not be applied
on the plane's border. The condition was incorrect and has been fixed in
the commit.

Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>
Reviewed-by: Andriy Gelman <andriy.gelman@gmail.com>
This commit is contained in:
Valery Kot 2020-06-22 17:29:21 +02:00 committed by Andriy Gelman
parent 235a5734e0
commit 855d51bf48
3 changed files with 3 additions and 3 deletions

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@ -294,7 +294,7 @@ static void double_threshold(int low, int high, int w, int h,
continue;
}
if ((!i || i == w - 1 || !j || j == h - 1) &&
if (!(!i || i == w - 1 || !j || j == h - 1) &&
src[i] > low &&
(src[-src_linesize + i-1] > high ||
src[-src_linesize + i ] > high ||

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@ -1 +1 @@
edgedetect 93ceace33f6636bcdbeb037317c65745
edgedetect 04ff46bb35edff3dbad4102391516d25

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@ -1 +1 @@
edgedetect-colormix 1b8658252e2f03fbae30e6d63dd24c7c
edgedetect-colormix 9f50c5586f899a8f5a10059154d64bde