Question

Possible Duplicate:
How to set ROI in OpenCV?

I’m trying to use a smoothing/blur filter on an image but only in a particular path /area of the source. (Using openCV currently)

How can that be done?

right now I’m doing something like

cv::GaussianBlur(im, newim, cv::Size(5,5),1.5);

But I would like to be doing

cv::GaussianBlur(im, newim, cv::Size(5,5),1.5,MyClosedPath);

I can also use any of the ios classes if it is easier to do. (Haven’t found a way for that yet either)

Answer 1

You can get a submatrix out of your original matrix eg:

cv::Mat subMat = originalMatrix(cv::Rect(x, y, width, height));

where x,y, width, height are the position of your subimage.
Then perform your gaussian blur on the submatrix.

[edit]
If you want to blur complex shapes, one way would be to blur the full image, and then use mat.copyTo with the mask of your blurred parts:

cv::Mat mask = ?; // this should be a CV_8U image with 0 pixels everywhere but where you want to blur the original image
cv::Mat blurred;
cv::gaussianBlur(image, blurred, cv::Size(5,5),1.5);
cv::Mat output = image.clone();
blurred.copyTo(output, mask);