possible unnecessary copy in aruco · charuco.cpp · detectCharucoDiamond

[esopalumpa]

in charuco.cpp in the aruco module there seems to be an unnecessary explicit copy of an image.

void detectCharucoDiamond(InputArray _image, InputArrayOfArrays _markerCorners,…
…

    // convert input image to grey
    Mat grey;
    if(_image.type() == CV_8UC3)
        cvtColor(_image, grey, COLOR_BGR2GRAY);
    else
	    _image.copyTo(grey);

If the image already is a grayscale-image it is explicitly copied. grey = _image.getMat(); should do.

EDIT:
same in _selectAndRefineChessboardCorners()

[alalek]

grey = _image.getMat()

doesn't copy buffer contents.

[esopalumpa]

grey = _image.getMat()

doesn't copy buffer contents.

Yes. The image is an InputArray and it is not necessary to copy the data here.

[alalek]

Agreed.
Implementation doesn't modify data from gray Mat.

Feel free to propose PR (preferable to 3.4 branch).

[esopalumpa]

PR #2785 against 3.4