How can I apply an algo of phase retrieval to an image in a specific axes created in my GUI?

Hi, I have to apply an algo of phase retrieval to an image in a specific axes created in my GUI. I can load the image and aplly a Roi, after this step I wrote the following code in order to read the image with selectode ROI in axes and after to apply the algo. But I am not able to do this.

if true
fullname = fullfile(filepath, filename);% image read in axes1
handles.tifImage = imread(fullname);
imagesc(tifImage); colormap(gray); 
end

[Geoff Hayes]

nick - where are you calling your algorithm? Why do you read the image and save to the handles structure as

 handles.tifImage = imread(fullname);

and then ignore handles on the following line (and so reference a variable that hasn't been defined)

 imagesc(tifImage);

[nick]

Hi Geoff, I call the algo in a section of my interface that is a popmenu in order to select the desired algo. I read the imahge as reported above because I defined handles in opening function

if true
 % Choose default command line output for interface
handles.output = hObject;
%add our own data fields
handles.File_Name = ['.TIFF'];
handles.Path_Name = ['C:\Users....];
handles.tifImage = ['*.tif'];
end