How can I crop selected portion of an image and place it in a white background?

I am trying to modify a code for watershed method segmentation, and the output figure is this. However, I want to subplot another image in this figure with only the tumor within the boundary in a blank background. How can I do it?

Answer 1

[Image Analyst]

Try this:

subplot(2, 1, 1);
% Display RGB image with yellow boundary burned into it.
imshow(rgbImage); % or display the gray scale image then call hold on and then call plot(xYellow, yYellow, 'y-', 'LineWidth', 3)
subplot(2, 1, 2);
% Mask the image using bsxfun() function to multiply the mask by each channel individually.  Works for gray scale as well as RGB Color images.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));
imshow(maskedRgbImage);

If you don't have mask, you can get it from the coordinates of the yellow boundary

[rows, columns, numberOfColorChannels] = size(rgbImage);
mask = poly2mask(xYellow, yYellow, rows, columns);

[Tawsif Mostafiz]

Thank you very much. It works! But the background is still black. I know it may be a silly question, but how doI turn it into white?

Answer 2

[Tawsif Mostafiz]

Nevermind, found it!