CODEWITHSUNDEEP
c++opencv
Max
Max

Reputation: 101

Open CV Mat structure coordinates

I am confused about the coordinates in OpenCV Mat structure. When I want to get a pixel I do something like this 

 image.at<Vec3b>(i,j)

The question is whether (0,0) coordinate is the top-left corner coordinate. I'm not sure about that, because when I try to get (-100,-100) it still works and gets a pixel.

Upvotes: 0

Views: 710

Answers (1)

Pierre
Pierre

Reputation: 1174

Yes it is the top-left.

From official documentation (for all pixel-access methods) here :

the 0-based row index (or y-coordinate) goes first and the 0-based column index (or x-coordinate) follows it

The at(-100,100) works because it is allowed to read (fast) everywhere in memory, but the data you get is not a pixel.

Upvotes: 1

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