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From: Varun on 20 May 2010 09:13
Hi all,

I am making a GUI for dicom images, I have already read the images from a series and stored them into a 3D matrix. Now the next step is I have to display each image one at a time. I am new to GUI programming but I have read the theor behind it. I cant understand how to program the slider callback function in order to display images one at a time !
Can anyone please help me with this ?

Thank You.

Regards,
Varun
From: RG on 20 May 2010 11:36
"Varun " <var3161(a)yahoo.co.in> wrote in message <ht3ch0$ni0$1(a)fred.mathworks.com>...
> Hi all,
>
> I am making a GUI for dicom images, I have already read the images from a series and stored them into a 3D matrix. Now the next step is I have to display each image one at a time. I am new to GUI programming but I have read the theor behind it. I cant understand how to program the slider callback function in order to display images one at a time !
> Can anyone please help me with this ?
>
> Thank You.
>
> Regards,
> Varun

Hi Varun,

I have done something similar using DICOM images, and I'm also a newbie with GUI programming. In my experience, if you want to show the images using 2D cross sections (one at a time) with the z-axis selected via a slider, you'll need to get comfortable using handles to pass values back and forth between objects in the GUI (using set and get functions). Generally speaking, any time you want to retrieve a property from an object you use the *get* function (get(handles.thatObject, 'property') substituting the 'property' string with whatever property it is you're trying to receive). When you want to apply a property to an object, you use the *set* function (set(handles.thatObject, 'property', value)).

So, let's say you are trying to display your image (dicomImg) on an axes called showImgAxes and your slider (z-slice selection) is called sliderZ:

1) After loading your image, set the Min, Max, and SliderStep values based on your 3D image size (z-dimension). This can be done using set(handles.sliderZ, 'Min', 1), etc.

2) The slider callback function (sliderZ_callback) executes every time you change the value of the slider. Thus, here is where you would add your imshow command:

2a) First, get the value of the slider:
currentSlice = get(hObject,'value');
2b) Next, set your image display axes as the current axes:
axes(handles.showImgAxes);
2c) Finally, display the image:
imshow(dicomImg(:,:,currentSlice));

Note that you can do the same for coronal and saggital sections using a similar idea (basically you'd create an x slider to show a y-z slice and a y slider to show an x-z slice).

Hope that helps.
RG
From: Varun on 21 May 2010 06:03
Hi RG,

Thanks a lot for posting such a detailed message, it really helped. but i like programmed as you said but then i am getting an error ->
????? The class "handles" is undefined.
Perhaps Java is not running.

Error in ==> GUI_without_GUIDE at 35
set(handles.slider1, 'Min', 1);


I have designed the GUI without GUIDE since this is just a small part of a larger GUI that i am supposed to build and my code looks like this ->

function GUI_without_GUIDE
%% Beginning of outer function red_blue
% Create figure

f = figure('Visible','on','Name','My GUI',...
'Position',[360,500,600,600]);
% Create an axes object to show which color is selected
Img = axes('Parent',f,'units','pixels',...
'Position',[50 50 512 512]);
% Create a slider to display the images
slider1 = uicontrol('Style', 'slider', 'Parent', f, 'String', 'Image No.', 'Callback', @slider_callback, ...
'Units', 'pixels', 'Position', [231 5 100 20]);

%DICOM image reading from the folder and setting slider parameters

% saving the file names in dirOutput
dirOutput = dir('*.dcm');
row = size(dirOutput,1);

% reading the DICOM images into the 3D array 'dicom_images'
for i = 1:row
info = dicominfo(dirOutput(i).name);
dicom_images(:,:,i) = dicomread(info);
end
dicom_images = mat2gray(dicom_images); %converting the matrix into grayscale

movegui(Img,'onscreen')% To display application onscreen
movegui(Img,'center') % To display application in the center of screen

imshow(dicom_images(:,:,1));
set(findobj(gcf,'type','axes'),'hittest','off');

set(handles.slider1, 'Min', 1);
set(handles.slider1, 'Max', row);
set(handles.slider1, 'SliderStep', 1);

%% Beginning of slider callback function
function slider_callback(h, eventdata)
axes(handles.Img);
imshow(dicom_images(:,:,currentSlice));
end
end



Thanks a lot again,
Varun
From: Varun on 21 May 2010 07:39
Hey RG,

I have completed the image viewer part. Thanks a lot for ur help, it was really very helpful.

Regards,
Varun
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