how to Define a region around each keypoint Extract using surf or sift detector

Good morning, everyone, I hope you are doing well.

Well, I have an image and I would like to extract the keypoints using the function of matlab :

F=extractSURFFeatures(Image);

At this point everything is fine, after the detection I want to define a region around each keypoint Extract using surf or sift detector, because my objectif is to extract regions (patches) as images for an other step of feature extraction. To better explain you can see the following image:

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