How do I get or calculate actual pixel dimensions of an image in an axes in a fully normalized figure?

I can not for the life of me seem to get the (screen) pixel values for height and length of a currently displayed image in an axes. The reason for this is the normal methods do not work, this is because everything in the GUI environment is set to 'normalized' for units.

So, the figure, the root, the axes, ....everything is set to normalized and so for example if I try to get the get(0,'screensize'); for my x and y (width and height) to make calculations about the pixels ...I'm just going to get [0 0 1 1] as an answer which doesn't tell me anything useful.

I'm trying to play a movie that goes back and forth between 2 images over and over (bar and bar2) and then ends by displaying bar.png in the axes (handles.flex a flexibly sized axes) at the very end. The problem however is that it isn't the right size. I tried to use the XLim and YLim, among other ways to get the right pixel values for x and y and ...it always ends up with my movie not being correctly scaled and stretched/shrunk to the axes length and height.

Example:

   bar2 = imread('GUI\base\bar2.png');
   bar = imread('GUI\base\bar.png');

   bar2 = imresize(bar2,[handles.flex.XLim(2) handles.flex.YLim(2)]);
   bar = imresize(bar,[handles.flex.XLim(2) handles.flex.YLim(2)]);

      loops = 40;
      frame(loops) = struct('cdata',[],'colormap',[]);
      for j = 1:loops
          if mod(j,2) == 0
              frame(j) = im2frame(bar);
          else
              frame(j) = im2frame(bar2);
          end
      end

    movie(handles.flex,frame,1);
    imshow(imread('GUI\base\bar.png'),'InitialMagnification', 'fit', 'parent',handles.flex);

Answer 1

[Image Analyst]

Until you load something into the flex axes control, it will have an xlim and ylim of 0 to 1. After you load an image into it xlim and ylim will have units of image pixels, not screen pixels. In other words, your image could be 3000 by 4000 pixels and displayed in a region on your screen of 600 by 800. xlim would be 1 to 4000, not 1 to 800.

I'm not really sure what you want to do, but perhaps the attached demo (that the Mathworks sent me and I modified) will help.

[gametjd]

What I really need is the screen pixel values as you mentioned.

Perhaps it's best not to focus on the XLim YLim section of the code as these were just a place holder until I could find an appropriate X and Y distance that consist of the screen pixel values that I want.

At this point in my program there will already be an image loaded into the flex axes. However this isn't the issue. Also, the zoom of any of this doesn't matter to me. I simply want to be able to in some way calculate values for the imresize arguments that are correct.

There are many ways I could calculate this but I can't seem to get information I need about the display to figure this out. All the values I look for are all relative to a display resolution size that I can't seem to get to or access in some way.

Obviously I know my own personal screen's resolution, but this should be able to work no matter who's display it's on. I'm using normalization so that all my UI elements are scaled correctly.

The problem here is that the movie() function doesn't have something like imshow's 'InitialMagnification' 'fit' option.

[Image Analyst]

Perhaps this will help: http://www.mathworks.com/help/matlab/creating_guis/designing-for-cross-platform-compatibility.html

Try getting the api for the display container. See documentation for iptgetapi(). It has tons of methods.

See attached example for how to use it. I don't know what all of those things are but one of them might help you.

[gametjd]

This gentleman was able to somewhat help me get the pixel values I wanted in a slightly simpler way. <http://www.mathworks.com/matlabcentral/newsreader/view_thread/348233#953287>

However, it seems that the problem isn't going to ever be 100% fixed because of a problem with the DPI of a figure that has yet to be addressed by Matlab developers. http://undocumentedmatlab.com/blog/graphic-sizing-in-matlab-r2015b