findContours alters the incoming image. (Bug #93)

Added by Jørn Christensen about 15 years ago. Updated almost 15 years ago.

Status:Done Start date:
Priority:Normal Due date:
Assignee:- % Done:

0%
Category:imgproc, video
Target version:-
Affected version: Operating System:
Difficulty: HW Platform:
Pull request:

Description

The findContours function is defined as 

void findContours( const Mat& image, vector<vector<Point> >& contours,
                   vector<Vec4i>& hierarchy, int mode,
                   int method, Point offset=Point());

with the const keyword on the image argument - but it still manages to change the image data. I'm not sure how it manages to do so, but I expect some (nasty) casts are involved. If the algorithm cannot work (efficient) without changing the data, the const keyword should be removed and the documentation updated as well.

History

#1
Updated by anonymous - almost 15 years ago

thanks! "const" qualifier was removed in r2926

  • Status changed from Open to Done
  • (deleted custom field) set to fixed

#2
Updated by Sebastian Krämer almost 15 years ago

So this means that the image is actually altered?? There should be a note about this in the docs so people can decide if they want to take an image copy for the contour finding algorithm. I would have preferred keeping the const (and findContours honoring it).

I'll reopen the bug so that the comment isn't lost.

  • Status changed from Done to Cancelled
  • (deleted custom field) deleted (fixed)

#3
Updated by James Bowman almost 15 years ago

Yes, this is a documentation bug.
Extra note added to FindContours in r2949.

  • Status changed from Cancelled to Done
  • (deleted custom field) set to fixed

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