how to make multiple ellipses in image (one inside another) and find the sum of pixels between two ellipses.

Dear Expert,

I have an tif file and i want to cut the elliptical part of from that image (which i am doing by the following code) . Although I can get sum of elliptical by the following method. But I want to make multiple elliptise(first ellipse and then second smaller ellipse inside the first one and so on) and i also want to know the sum of pixels between two ellipses. I am attaching an image showing how I want to draw the ellipses.

Thank you

[FileName,PathName] = uigetfile({'*.jpg;*.tif;*.png;*.gif','All Image Files'},'Please Select an Image');
image = imread([PathName FileName]); 
imshow(image) %needed to use imellipse
user_defined_ellipse = imellipse(gca, []); % creates user defined ellipse object.



wait(user_defined_ellipse);% You need to click twice to continue. 


MASK = double(user_defined_ellipse.createMask());


new_image_name = [PathName 'Cropped_Image_' FileName];

new_image_name = new_image_name(1:strfind(new_image_name,'.')-1); %removing the .jpg, .tiff, etc 
new_image_name = [new_image_name '.tif']; % making the image .png so it can be transparent
imwrite(image, new_image_name,'png','Alpha',MASK);
msg = msgbox(['The image was written to ' new_image_name],'New Image Path');
waitfor(msg);

cropped_img_sum = imread(new_image_name);
winopen(new_image_name);
cropped_img = sum(sum(cropped_img))

Answer 1

[Image Analyst]

That's exactly what my demo does. See attached demos.

meanInsideEllipse =

100.464150943396

areaOfEllipse =

9805

You could of course sum all the gray levels inside if you wanted by adding this:

sumInsideEllipse = sum(monochromeImage(maskImage))

[SHUBHAM AGARWAL]

Dear Expert,

Sorry, for the earlier question. I have edited my question as I want to make multiple elliptise(first ellipse and then second smaller ellipse inside the first one and so on) and i also want to know the sum of pixels between two ellipses. I am attaching an image showing how I want to draw the ellipses.

Thank you

[Image Analyst]

You can get a mask for each ellipse. Then get an annular mask like this:

ringMask = largerEllipseMask & ~smallerEllipseMask;

Then use the ring mask in the equations, like

sumInsideEllipse = sum(monochromeImage(ringMask))

[SHUBHAM AGARWAL]

Dear Expert,

I want to zoom into the image before making ellipse. I am trying the zoom option in imshow but then after zoom in i can not fraw the ellipse.How can it be done?

Thank you

[Image Analyst]

@SHUBHAM AGARWAL I don't know. Not all of the Image Processing functions work well if you have changed the zoom. It might not be possible. Call tech support for a definitive answer.