How to apply a rectangular window on an image?

Hello, I want to scan a dicom picture with a rectangular window. I do not know how to apply the window. Also I want to know if my codes are correct for making a rectangular or not. These are my codes :

w=sigwin.rectwin; winwrite(w);

I guess it will create window by length 64. how can I change the length and width of my window?

Thanks

Answer 1

[Image Analyst]

Use conv2() or imfilter():

windowWidth = 63; % Should be an odd number!
windowHeight = 33; % Should be an odd number!
% Make uniform window which will take average and make it blurry.
kernel = ones(windowHeight, windowWidth ) / windowHeight * windowWidth;
output = conv2(grayImage, kernel, 'same');
% or
output = imfilter(grayImage, kernel);

[Faranak]

This code makes something like noise on image,I want to open a rectangular window and apply it to scan over my image,I want it to detect and count the number of nonzero pixel in that rectangular window on the image.

[Image Analyst]

Then do this:

windowWidth = 63; % Should be an odd number!
windowHeight = 33; % Should be an odd number!
% Make uniform window which will take the sum in the window.
kernel = ones(windowHeight, windowWidth );
output = conv2(grayImage, kernel, 'same');
% or
output = imfilter(grayImage ~= 0, kernel);

output pixel is the sum of all non-zero pixels within the window centered over that output pixel.

[Faranak]

I tried your code but it is not what I want. In the picture attached you can see a dicom image of breast and also a small rectangular window on the image.I want this. A small rectangular window on the image which is scanning breast and detect and counts the number of nonzero pixels. Thank you for your help.

[Image Analyst]

There are no non-zero pixels in that image. If you want to count all pixels darker than some threshold value then you can binarize the image first

thresholdValue = 50; % or whatever...
binaryImage = grayImage < thresholdValue;
output = conv2(binaryImage, kernel, 'same');