using gui slider to display 3d image stack

[Alex]

I am new to GUI programming. I am trying to do the following:
1. Display an 3-D MRI image (represented as a stack of 2D images).
2. Use a slider to scroll through each image in the stack.
3. Get the axis coordinates on the image when the user clicks on the image.

I am having the following problems.
1. As soon as I scroll using the slider, I am no longer able to get the pixel info.
2. My slider will not scroll through every image. It gives non-integer values, so I use round(), but not every slice is represented.

I think my problems are that the figure is not refreshed after a callback and I don't know how to set the step size on the slider, but I don't know how to fix either of these. My code is below.

%%%%%%%%%%%%%%%%%%%%%%%

function displayIm3d(im)

sizeImg = size(im);
minSlice = 1;
maxSlice = sizeImg(3);
startSlice = round((maxSlice-minSlice)/2);

% Create a figure without toolbar and menubar.
hfig = figure('Toolbar','none',...
'Menubar', 'none',...
'Name','MRI Viewer',...
'NumberTitle','off',...
'IntegerHandle','off');

slider1 = uicontrol(hfig,'Style','slider','Callback',@slider1_Callback);

set(slider1,'value',startSlice); %
set(slider1,'max',maxSlice); %
set(slider1,'min',minSlice);

slice = get(slider1,'Value'); % returns position of slider

% Display the image in a figure with imshow.
himage = imshow(im(:,:,slice),'DisplayRange',[ ]);

hpixinfo = impixelinfo(himage);

set(himage,'ButtonDownFcn',@pixelInfo)

function slider1_Callback(slider1,eventdata,handles)
% update the displayed image when the slider is adjusted
slice = round(get(slider1,'Value'));
imshow(im(:,:,slice),'DisplayRange',[]);

end

function pixelInfo(cursor,eventdata,handles)
% get coordinates of clicked pixel
[ x, y ] = ginput(1)

end

end

[ImageAnalyst]

If you're using a slider going from 0-1, then set the small step size
to be 1/numberOfSlices, and the large step size to be about 10 times
that. Check the calculated slice number to make sure it's not less
than 1.

Otherwise, I think you can just set the max value of the slider to be
numberOfSlices, and the small step size to be 1.

[Alex]

ImageAnalyst <imagea...@mailinator.com> wrote in message <46d17bdd-9920-4f27...@v23g2000vbi.googlegroups.com>...

Great. Thank you. How should I go about fixing the other problem, that is, having the gui refresh/update after the slider is moved? The current callback function will change the image displayed, but the rest of the gui loses its functionality.

[ImageAnalyst]

The rest of the GUI should not lose its functionality. Chances are
you didn't have a try/catch and it encountered an error. Look in the
command window right after you move the slider and look for a bunch of
red error messages.

Long shot: Look for 'enable' in your code - you might be disabling
the controls, but I doubt it.

You might also try drawnow - that is used to force a screen update and
is most useful when you've changed something but then immediately
enter into an intensive loop - so intensive that the figure never gets
a chance to update itself.

[Mark Pether]

Hi Alex,

I was just wondering if you ever got a solution to this? I am having problems with exactly the same problem.

Thanks