how to use submat for a non square image

asked 2016-09-04 05:51:26 -0600

elish
41 ●2 ●7

Hi,

I am working on an augmented reality app in android,
I am trying to overlay an image that is a shape of a star, its not a full squar onto the camera frame,

       dst.copyTo(submat);

but i get a black square in roi area and in the middle is the star.

How can i limit the size of submat to be the shape i want,
Is there a way to copy pixels instead of rows and cols?

Thank you!!

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answered 2016-09-04 06:39:09 -0600

berak
32993 ●7 ●81 ●312

you can use a mask with copyTo().

so, first make a black image:

Mat mask = new Mat(submat.size(), CvType.CV_8U, new Scalar(0));
// then draw a filled white star into that,
// e.g. with drawContours(), and linesize=-1
//
// now use that mask, to copy only where the mask is white:
dst.copyTo(submat, mask);