storing a cropped image into a variable and saving the image using imwrite()

I have another question. I created a GUI that takes photo using a webcam and from there allows the user to crop the image to the size of their choosing. However I want to store that cropped image into a variable but when I set it equal to a variable, MATLAB says that the variable is empty. Here is the code I used:

handles.output = hObject;
clc
axes(handles.axes1);
vid = videoinput('winvideo',1,'YUY2_320x240');
start(vid);
vid.ReturnedColorspace = 'rgb';
im = getdata(vid,1);
tb = rgb2gray(im);
croppedImage = imcrop(tb);
figure, imshow(croppedImage);
imwrite(croppedImage, 'standardImage.tif');

axis off;

[Jan]

Which variable is empty afterwards? And where do you test this?

Answer 1

[Walter Roberson]

Are you doing, http://www.mathworks.com/help/images/ref/imcrop.html

create the cropped image by double-clicking the left mouse button or by choosing Crop Image from the context menu.

?

[Bob]

The user crops the image by choosing the range and by double clicking with the left mouse button.