Crop an image using multiple coordinates

I used the "imfreehand" to crop an irregular shape and save its positions into a variable. This position variable is a 85*2 double matrix (85 points, X and Y coordinates). Now, I want to use the same position to crop another image (different layer of the image, but the location of the objects is the same). The functions I can find all requires rectangle positions (X1,X2,Y1,Y2). In my situation, I have 82 different (X,Y) coordinates, how can I use the position information to crop a new image?

Answer 1

[Matt J]

You should save the original imfreehand object, h.

   h=imfreehand(_____)

Then you can just do

   cropped = double(AnotherImage).*h.createMask

Answer 2

[Image Analyst]

See my freehand copy and paste demo. It will be easy for you to adapt it.

Answer 3

[Image Analyst]

"I want to crop another image (different layer of the image)." Perhaps you want to mask all the layers/slices of this or another image. So use bsxfun:

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

rgbImage can be a color image, or a volumetric (multi-slice) image.

[Matt J]

My answer should cover this as well, if you have R2016b or later.