How to detect and separate pixels in an image

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I want to take an image and detect pixels that are green, which I've accomplished. But I also want to keep their color and seprate them such that I can then take the rest of the image and convert it to greyscale. Here is the code I have currently that detects the green pixels:
function [ result ] = detectGreen( rgbimage )
%set the threshold of green in the hue channel
GREEN_THRESHOLD = [65,170]/360;
%convert image to HSV color space
hsv = rgb2hsv(rgbimage);
%find pixels in the relevent area that are in the range in H and V channels
greenMask = hsv(:,:,1)>GREEN_THRESHOLD(1) & hsv(:,:,1)<GREEN_THRESHOLD(2) & hsv(:,:,3) > INTENSITY;
%return the green pixels
result = greenMask;
Currently, this takes the color image and processes it to be like the second image:
Is there a way that I can keep the green color of those detected pixels such that I can then convert the whole image to grey scale and overlay the detected white on top so that the only thing in color is the green of the field?

Accepted Answer

Subhadeep Koley
Subhadeep Koley on 6 May 2021
rgbImg = imread('image.png');
grayImg = rgb2gray(rgbImg);
greenMask = detectGreen(rgbImg);
hold on
han = imshow(grayImg);
hold off
set(han, 'AlphaData', ~greenMask);

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