how to find a sub image in an image and converting it to grayscale?

Hello,

I have an image and a sub image which is cropped out of the image.

    (img, img_w)
    val1 = imread(img);
    val2 = imread(img_w);

    gray1 = rgb2gray(val1);%grayscaling both images
    gray2 = rgb2gray(val2);

    matchingval = normxcorr2(gray1,gray2);%normalized cross correlation 

    [max_c,imax]=max(abs(matchingval (:)));

After this I am stuck. I have no Idea how to change the whole image grayscale except for the sub image which should be in color.

How do I do this?

Thank you.

Answer 1

[Image Analyst]

This is exactly what I do in my attached demo, except that it's in color. Your situation might be a little simpler.