How can I handle camera on GUI(axes) by using imaq.VideoDevice?

I want to show camera on axes(or uipanel) in GUI but I use 'imaq.VideoDevice' syntax.

I only found answer for 'videoinput'

like this -->>

vid = videoinput('winvideo',1);
hImage=image(zeros(699,1500,1),'Parent',handles.axes1);
preview(vid,hImage);

I want to show it like this but in imaq.VideoDevice way.

Can anybody give me an idea T^T

Thank you...

Answer 1

[Image Analyst]

For what it's worth, here's my code (a small snippet from a logitech web cam app). It's long because it's more robust and general purpose than yours and also spits out useful information to the command window:

%=====================================================================
function InitializeVideoCamera(handles)
  % Initialize the video camera.
  global vidobj;  % Video camera object.
  try
    % First see if any video mode is selected in advance.  If it is, we should use that if we can.
    % Now get the selection from the lstVideoModes listbox.
    lstVideoModes = get(handles.lstVideoModes, 'String');
    lstSelectedItem = 1; % Flag for indicating no video mode is selected.
    if ~isempty(lstVideoModes)
      lstSelectedItem = get(handles.lstVideoModes, 'Value');
      % Let's see what it is, just for fun.
      if ~isempty(lstSelectedItem)
        selectedVideoMode = lstVideoModes{lstSelectedItem};
      end
    end
    
    % Print info to command window:
    hardwareInfo = imaqhwinfo % Print what cameras are there.
    adaptorNames = hardwareInfo.InstalledAdaptors;
    % Might look something like:
    % InstalledAdaptors: {'dcam'  'gentl'  'gige'  'lumeneraimaqw64'  'matrox'  'winvideo'}
    matches = strfind(adaptorNames, 'winvideo');
    % Find out which index is the Lumenera Camera.
    winvideoIndex = find(~cellfun(@isempty, matches));
    thewinvideoAdaptor = adaptorNames{winvideoIndex}
    % Print out other useful information to the command window.
    hw2 = imaqhwinfo(thewinvideoAdaptor);
    devInfo = hw2.DeviceInfo
    numberOfImagingDevices = length(devInfo)
    logitechModes = '';
    for d = 1 : numberOfImagingDevices
      thisDevice = devInfo(d); % A structure.
      defaultFormat = thisDevice.DefaultFormat; % A character array.
      deviceFileSupported = thisDevice.DeviceFileSupported; % A logical.
      devName{d} = thisDevice.DeviceName; % A cell.
      devID = thisDevice.DeviceID; % A double
      videoInputConstructor = thisDevice.VideoInputConstructor; % A character array.
      videoDeviceConstructor = thisDevice.VideoDeviceConstructor; % A character array.
      SupportedFormats{d} = thisDevice.SupportedFormats; % A cell array
      numberOfSupportedFormats(d) = length(SupportedFormats);
      % Print out stuff to command window.
      fprintf('\nFor device #%d, named %s, the attributes are:\n    DefaultFormat = %s\n    DeviceFileSupported = %d\n    DeviceID = %d\n    VideoInputConstructor = %s\n    VideoDeviceConstructor = %s\n',...
        d, devName{d}, defaultFormat, deviceFileSupported, devID, videoInputConstructor, videoDeviceConstructor);
      % Let's start a counter for the video modes if it's the Logitech camera.
      if strfind(lower(devName{d}), 'logitech')
        modeCounter = 1;
      end
      % Print out all the supported formats for this device.
      fprintf('    For device named : %s, the supported formats are:\n', devName{d});
      for k = 1 : numberOfSupportedFormats(d)
        theseFormats = SupportedFormats{k}
        for k2 = 1 : length(theseFormats)
          thisFormat = theseFormats{k2};
          fprintf('        Format #%d = %s\n', k2, thisFormat);
          % If the device name contains Logitech, and the format contains RGB, let's add the mode to the listbox.
          if ~isempty(strfind(lower(devName{d}), 'logitech')) && ~isempty(strfind(thisFormat, 'RGB'))
            logitechModes{modeCounter} = thisFormat;
            modeCounter = modeCounter + 1;
          end
        end
      end
    end
    % Add the modes to the listbox:
    if ~isempty(logitechModes)
      set(handles.lstVideoModes, 'string', logitechModes);
    end
    % The device name, devName, might be something like : {'Hauppauge WinTV 885 Video Capture'  'Logitech QuickCam Ultra Vision'}
    % Find the one that is for our Logitch camera.
    matches = strfind(devName, 'Logitech');
    % Find out which index is the Logitech Camera.
    LogitechIndex = find(~cellfun(@isempty, matches));
    % Get the Logitech device:
    LogitechCamera = devInfo(LogitechIndex);
    % Get the device ID:
    LogitechDeviceID = LogitechCamera.DeviceID;
    % Now we know which device is the Logitech camera.  Now let's let the user pick some RGB modes;

    % Initialize winvideo webcam with the first mode on the list.
    % Or the selected mode if one was selected in advance of entering this function.
    vidobj = videoinput(thewinvideoAdaptor, LogitechDeviceID, logitechModes{lstSelectedItem});
    if ~isempty(vidobj)
      src = getselectedsource(vidobj);
      vidobj.FramesPerTrigger = 1;
      axes(handles.axesImage);
      hImage = findobj(handles.axesImage, 'Type', 'image');
      preview(vidobj, hImage);
%       src.ZoomMode = 'manual';
      % Turn on the live video preview.  Display the bounding box over it if there is one selected.
      TurnOnLiveVideo(handles);
    end
    % Turn on the live video preview.  Display the bounding box over it if there is one selected.
    TurnOnLiveVideo(handles);
  catch ME
    errorMessage = sprintf('Error in function logitech_webcam_OpeningFcn.\nNo Logitech webcam detected!\nMake sure you plug in your webcam BEFORE you start MATLAB, NOT AFTER!\n\nError Message:\n%s', ME.message);
    fprintf('%s\n', errorMessage);
    set(handles.txtInfo, 'string', errorMessage);
    uiwait(warndlg(errorMessage));
  end

[Ara]

I'm trying to understand your code. Thank you :)

Answer 2

[Geoff Hayes]

The code should be very similar to that for the videoinput object. See imaq.videodevice and preview for details.

An example could be

 vidobj = imaq.VideoDevice('winvideo', 1);
 hImage=image(zeros(699,1500,1),'Parent',handles.axes1); 
 preview(vidobj,hImage);

Try the above and see what happens!

[Ara]

It show that "Too many input arguments."

and if I open camera with "step" and looping it, not preview. Is it similar like preview?

Thank you for your answer :)

[Geoff Hayes]

Ara - which statement gives the error too many input arguments?

As for step, it appears to be similar to preview except that you are having to create the loop to get one frame at a time.

[Ara]

It show like this on command window

Error using imaq.VideoDevice/preview Too many input arguments.

Error in untitled>pushbutton1_Callback (line 83) preview(vidobj,hImage);

[Geoff Hayes]

Sorry about that, Ara. My suggestion is invalid as it looks like preview in only applicable to videoinput objects. I guess the problem with using just

 preview(vidobj)

is that a separate window, outside of your GUI, appears. Is that correct?

[Image Analyst]

Well preview certainly takes 2 input arguments so I'm not sure I understand that error message. One possibility might be that somehow vidobj or hImage is an array rather than a single thing. Check with "whos" before calling preview.

Or the problem might be that his code is in a pushbutton callback and vidobj is not in scope. He can solve this by putting the line

global vidobj;

in the function where he instantiated vidobj and in the function pushbutton1_Callback().

[Jia Zhen]

hi, so is there really no way to use imaq.VideoDevice for preview in axes without opening another window as George Hayes had say? I really dont want to use videoinput as it would cause my visioncascadeobject detector to malfunction. Thanks.

[Image Analyst]

I don't know. I've never used visioncascadeobject and I don't know why that would malfunction if you had a video input object. I suggest you call the tech support.

Answer 3

[Ankit Singh]

How to close hImage figure is always on

[Image Analyst]

Try

delete hImage;

Or

clear hImage;