applying mask on an image

Hello,

any help of how to write this code or how to start it?

Consider the “ctskull-256” image, apply a mask on it to only extract the

intensity above half of the peak intensity (that is, to set them to 1 and set

the pixel intensity below this level to 0). Compare the result with

FIGURE2.21(h) in your textbook, what do you find?

Answer 1

[Image Analyst]

To create a mask like you said:

maxGL = max(grayImage(:))
mask = grayImage > maxGL/2;

To apply the mask to an RGB image, use this code:

% Mask the image using bsxfun() function to multiply the mask by each channel individually.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));

If it's grayscale, you can do it simpler like this:

grayImage(~mask) = 0;