How to only smooth local area

For example
1.just process the area(A area):Rect[100,120,230,240] by GaussianBlur and other area(B area) doesn’t change in the 1920*720 image;
2.the process result (A area)and other area(B area) display in the one image.

please show, what you’ve tried

I I draw the ROI and process it,then use the function copyTo.However,the area of Rect[100,120,230,240] in image is the mergence of the GaussianBlur image and original image.

can we start all over here ?

  • please show our code and example image
  • then, try to explain by example, what you wanted to achieve
    (and what you dont like about the outcome)

I have the src image and dst image now in my phone.I want to know how to realize it