How to assign each axes to hold/keep its own image?

Hi

I have this set of lines

set(get(gca,'children'),'cdata',squeeze(Img(:,:,S,:))); %% For Axes 1
set(get(gca,'children'),'cdata',squeeze(Img2(:,:,S2,:))) %% For Axes 2
set(get(gca,'children'),'cdata',squeeze(Img3(:,:,S3,:))) %% For Axes 3

But because of the hierarchy sequence I only get the Img3 at all axes. When I click upon each one of the axes I get the last image I assigned on this set of lines. How do I make it to keep its image for every each axes seperately? So Axes 1 should have Img, Axes 2 Img2 and Axes 3 Img3

Answer 1

[Rik]

You should never use gcf or gca in code for a GUI. As your tags indicate you're using GUIDE: use the explicit handles to the axes object stored in the handles struct.

[Stelios Fanourakis]

So you say to try something like that

set(get(handles.axes1,'children'),'cdata',squeeze(Img(:,:,S,:))); %%For Axes 1
set(get(handles.axe2,'children'),'cdata',squeeze(Img2(:,:,S2,:))); %%For Axes 2
set(get(handles.axes3,'children'),'cdata',squeeze(Img4(:,:,S3,:))); %%For Axes 3

I am going to try and let you know the outcome.

[Rik]

Or even better: replace the get(handles.axes1,'children') by the direct handle to the image object (which is returned by the function that created it).

[Stelios Fanourakis]

I fixed the 2 axes but the first one remained faulty and now I get the error

Error using matlab.graphics.primitive.Data/set
There is no cdata property on the Line class.

Regarding this line

set(get(handles.axes1,'children'),'cdata',squeeze(Img(:,:,S,:))); %%For Axes 1

[Rik]

And that is why I suggested using the direct handle. Apparently the axes has a line object as a child (as well?). If you want to change the CData of the image object you should store the handle to that object in the guidata struct.

[Stelios Fanourakis]

And what is a direct handle of my image at the moment?

[Stelios Fanourakis]

Is this what you mean by direct handle to an image??

i3 = imshow(squeeze(im4(:,:,slice1,:)),'XData',[1 592], 'YData',[1 481]);

[Stelios Fanourakis]

I tried that solution and it works. However, when I drag the slider manually and then try again to move it by scrolling the wheel I get the error

Error using matlab.graphics.primitive.Image/set
Invalid or deleted object.

Error in experiment/mouseScroll (line 271)
set(i1,'cdata',squeeze(im2(:,:,S,:))); %%For Axes 1
 
Error using experiment/XSliderCallback (line 217)
Error while evaluating Figure WindowScrollWheelFcn.

Why this error?

[Rik]

That is indeed what I mean. I would try to find the cause of the image object being deleted. It is also a smart move to include the parent axes in your call to imshow (or image) so they don't have to implicitly call gca, which might overwrite things in your axes (especially in the case of imshow, which does a lot of housekeeping for you).

[Stelios Fanourakis]

Can you please give me an example? Something like that?

i3 = imshow(squeeze(im4(:,:,slice1,:)),'XData',[1 592], 'YData',[1 481], 'parent' handles.axes3);

[Stelios Fanourakis]

How can I find the cause of the image object being deleted? Is there a specific procedure since the error message is a bit vague.

[Stelios Fanourakis]

Now it's not working and I get the error

Index exceeds matrix dimensions.

Error in experiment/mouseScroll (line 273)
set(i1,'cdata',squeeze(im2(:,:,S,:))); %%For Axes 1
 
Error while evaluating Figure WindowScrollWheelFcn.

[Rik]

Almost: you're missing a comma here.

i3 = imshow(squeeze(im4(:,:,slice1,:)),'XData',[1 592], 'YData',[1 481], 'parent',handles.axes3);
%                                                          ----------------------^

And the best way to find where an object is being deleted is to step through the code. You can also try setting the DeleteFcn:

i3 = imshow(squeeze(im4(:,:,slice1,:)),'XData',[1 592], 'YData',[1 481], 'parent',handles.axes3);
set(i3,'DeleteFcn','error(''object is being deleted'')')

Now you can set the stop on error debugging option to find out when the object is being deleted.

[Stelios Fanourakis]

Now I get the error

Index exceeds matrix dimensions.
Error in experiment/mouseScroll (line 273)
set(i1,'cdata',MyMatrix(:,:,S,:)); %%For Axes 1 
Error while evaluating Figure WindowScrollWheelFcn.

Any idea why Index could exceed matrix dimensions?

[Rik]

How did you code the value of S? Are you making sure it is capped to the size of the dimension that changing?

[Stelios Fanourakis]

S stands for the slices that needs to be changed at every sliding

 S = round((get(handles.SliderFrame1,'Value')));
        S2 = round((get(handles.SliderFrame2,'Value')));
        S3 = round((get(handles.SliderFrame3,'Value')));
        
        
         UPDN = eventdata.VerticalScrollCount;
        S = S - UPDN;
        S2 = S2 - UPDN;
        S3 = S3 - UPDN;
        
        if (S < 1) | (S2 < 1) | (S3 < 1) 
            
            S = 1;
            S2 = 1;
            S3 = 1;
            
        elseif (S > sno) | (S2 > sno) | (S3 > sno)
            
            S = sno;
            S2 = sno;
            S3 = sno;
        
        
set(handles.SliderFrame1,'Value',S);
set(handles.SliderFrame2,'Value',S2);
set(handles.SliderFrame3,'Value',S3);

%% where sno = number of slices

After that script follows the one with the error

set(i1,'cdata',squeeze(Img(:,:,S,:))); %%For Axes 1
set(i2,'cdata',squeeze(Img2(:,:,S2,:))); %%For Axes 2
set(i3,'cdata',squeeze(Img4(:,:,S3,:))); %%For Axes 3

[Rik]

Where did you define sno? Because if that is higher than size(Img,3) it will cause this error.

[Stelios Fanourakis]

This Index Exceeds Matrix Dimensions is a new error. How can I trace its origin? I don't know but with the same commands it used to run.

[Stelios Fanourakis]

@Rik, sno = size(im2) It is defined at the begining of the script making it global value

Why it shouldn't be higher than the number of slices (Img,3)

[Stelios Fanourakis]

I append the whole mouse scroll function here. Hope you can help me.

function mouseScroll(~,eventdata,I)

handles = guidata(gcf);

S = round((get(handles.SliderFrame1,'Value')));
S2 = round((get(handles.SliderFrame2,'Value')));
S3 = round((get(handles.SliderFrame3,'Value')));


sno = size(MyMatrix);

UPDN = eventdata.VerticalScrollCount;
S = S - UPDN;
S2 = S2 - UPDN;
S3 = S3 - UPDN;

if (S < 1) | (S2 < 1) | (S3 < 1)
    
    S = 1;
    S2 = 1;
    S3 = 1;
    
elseif (S > sno) | (S2 > sno) | (S3 > sno)
    
    S = sno;
    S2 = sno;
    S3 = sno;
    
    global S S2 S3
    
    
    set(handles.SliderFrame1,'Value',S);
    set(handles.SliderFrame2,'Value',S2);
    set(handles.SliderFrame3,'Value',S3);
    set(handles.Edit1, 'String', sprintf('Slice# %d / %d',S, sno));
    
    
else
    set(handles.Edit1, 'String', '2D image');
end

set(i1,'cdata',squeeze(im2(:,:,S,:))); %%For Axes 1
set(i2,'cdata',squeeze(im3(:,:,S2,:))); %%For Axes 2
set(i3,'cdata',squeeze(im4(:,:,S3,:))); %%For Axes 3
end

Where MyMatrix = im2 and im3 and im4 are actually the same image under permutation. But the sizes are the same

[Rik]

Consider this example:

MyMatrix=rand(100,120,40);
S=40;
sno=size(MyMatrix)

%now your callback runs:
S=S+1;
cond=(S > sno) | (S2 > sno) | (S3 > sno);
clc,disp(cond)

What do you think if will do when you input your conditional? If you aren't 100% sure, it is probably not what you think.

You should always make sure to have a scalar input to if and while. In your case I would suggest something like this:

function mouseScroll(hObject,~,I)
%you aren't using I, and with GUIDE the third input is usually 'handles'
handles = guidata(hObject);
im2=handles.im2;i1=handles.i1;
im3=handles.im3;i2=handles.i2;
im4=handles.im4;i3=handles.i3;

S(1) = round((get(handles.SliderFrame1,'Value')));
S(2) = round((get(handles.SliderFrame2,'Value')));
S(3) = round((get(handles.SliderFrame3,'Value')));

UPDN = eventdata.VerticalScrollCount;
S=S-UPDN;

S=max([1 1 1],S);%ensure S is at least 1
S=min(size(im2),S);%ensure S is at most size(im2,___)

set(handles.SliderFrame1,'Value',S(1));
set(handles.SliderFrame2,'Value',S(2));
set(handles.SliderFrame3,'Value',S(3));
set(handles.Edit1, 'String', sprintf('Slice# %d / %d',S(3), sno(3)));

set(i1,'cdata',squeeze(im2(:,:,S(1),:))); %%For Axes 1
set(i2,'cdata',squeeze(im3(:,:,S(2),:))); %%For Axes 2
set(i3,'cdata',squeeze(im4(:,:,S(3),:))); %%For Axes 3
end

[Rik]

Also, don't use global variables, they will only cause trouble.

[Stelios Fanourakis]

I also get this error

Error in experiment/mouseScroll (line 243)
im2=handles.im2;i1=handles.i1;
 
Error while evaluating Figure WindowScrollWheelFcn.

Reference to non-existent field 'im2'.

[Rik]

You should be able to find the cause of this error on your own. The code is attempting to assign a value to the variable im2, and it tries to do that by extracting a field from the handles struct. Apparently that field doesn't exist.

When writing this code, I assumed you had it stored in the handles struct, because that makes the most sense. Replace this code with whatever name you have stored your image in the struct.

[Stelios Fanourakis]

After renaming everything using handles.im2,handles.im3 and so on so forth I get a new error

Undefined variable "eventdata" or class "eventdata.VerticalScrollCount".
Error in experiment/mouseScroll (line 251)
UPDN = eventdata.VerticalScrollCount; 
Error while evaluating Figure WindowScrollWheelFcn.

I didn't have that error previously

[Rik]

Ah, that one is on me, I edit the function header without checking if you were indeed not using eventdata (since I hardly ever use it).

function mouseScroll(hObject,~,I)
%change to
function mouseScroll(hObject,eventdata,I)

You should also confirm that you haven't changed the callback. Because if you haven't, the third input in a GUIDE-generated GUI is the handles struct.

[Stelios Fanourakis]

Dear RIk

Thank you so much for your valuable contribution. My Viewer seems to work at the moment.

However the mouse scrolling stops only at the left end whereas at the right end of the slider I get the error

Warning: 'slider' control cannot have a 'Value' outside of 'Min'-'Max' range
Control will not be rendered until all of its parameter values are valid 
Index exceeds matrix dimensions.
Error in experiment/mouseScroll (line 259)
set(i1,'cdata',squeeze(im2(:,:,S(1),:))); %%For Axes 1 
Error while evaluating Figure WindowScrollWheelFcn.

[Rik]

Use the debugger. Follow the flow of your program. Find out where the properties of your slider are set. Find out when the results are different from what you expect.

The warning you see tells you that some code is setting the value property to something bigger than max. And then you get error that tells you your index is too big. That means either my code doesn't work, or the size is not retrieved correctly. Check both options.