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overlay image with offset

asked 2014-08-21 05:34:11 -0500

borjaevo gravatar image


I'm trying to get a function that do this. I attached and image to explain you. Have two images of same type and size, that are blue and green. I want to overlay the green image over the blue with an offset, in this case x and y are negative and only overlay the part of the image that is in common coordinates (red area). Are there an easy way to do this?

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You can create mask for red region and use this mask for overlay. For creating mask, threshold both green and blue and perform bitwise_and on results.

Haris gravatar imageHaris ( 2014-08-21 07:18:15 -0500 )edit

maybe i have not explained well, sorry for my english. Colors are an example, blue and green are source images, and dst is blue with a part of green image overlayed (red area) in this case (negative offset).

borjaevo gravatar imageborjaevo ( 2014-08-21 10:47:02 -0500 )edit

So how will you decide the portion green overplayed on blue, do you have co-ordinates for it?

Haris gravatar imageHaris ( 2014-08-21 11:12:57 -0500 )edit

Yes, coordinates are obtained from another device. If the with of both images is 640pixels my x offsets values can be from -640 to 640. With other values images are not overlayed. In the example, x offset can be about -400pixels. if offset is 0, images are completely width overlayed Thank you.

borjaevo gravatar imageborjaevo ( 2014-08-21 12:05:55 -0500 )edit

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answered 2014-08-23 09:21:43 -0500

Haris gravatar image

You can use ROI to overly the source on destination.

Assume you got the co-ordinates like

int x= //overlay x
int y= //overlay y
int width = //overlay width
int height = //overlay height

Mat green; // source image.
Mat blue; //destination image.
Mat ROI1=green(Rect(x,y,width,height));//Apply RIO on source image from which overlay portion taken.
Mat ROI2 = blue(0,0,width,height);// assume you have to apply overlay from (0,0).
ROI1.copyTo(ROI2)// copy overlay to destination
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Asked: 2014-08-21 05:34:11 -0500

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Last updated: Aug 23 '14