MATLAB: How to preview live video in App Designer using videoinput and preview

appdesignerMATLABpreviewvideoinput

I am trying to capture live feed from a camera in App Designer. At the command window I can use "videoinput" and preview to do this, but it's not working in my app. How do I do this?

vid = videoinput('winvideo',1);
preview(vid)

Best Answer

In order to preview the video in your uiaxes, you can create an image and preview the video on that image:

% Image acquisition
vid = videoinput('winvideo',1);
% Create blank image
hImage = image(app.UIAxes,zeros(720,1280,3)); %If image resolution is 1280x720
pause(2)
% These lines set proper aspect ratio
app.UIAxes.XLim = [0,1280];
app.UIAxes.YLim = [0,720];
app.UIAxes.XTick = [];
app.UIAxes.YTick = [];
pbaspect(app.UIAxes,[1280,720,1])
% Preview the image
preview(vid,hImage)

Related Solutions

MATLAB: App Designer: How to use a camera in different Callbacks

Hi,

Folllowing is the code and app design

classdef app1 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure  matlab.ui.Figure
        UIAxes    matlab.ui.control.UIAxes
        UIAxes2   matlab.ui.control.UIAxes
        Button    matlab.ui.control.Button
    end
    
    properties (Access = public)
        cam;
    end
    
    % Callbacks that handle component events
    methods (Access = private)
        % Code that executes after component creation
        function startupFcn(app)
            app.UIAxes2.Visible = 'off';
            evalin("base", 'clear cam');
            app.cam = webcam;
            frame = snapshot(app.cam);
            im = image(app.UIAxes, zeros(size(frame), 'uint8'));
            axis(app.UIAxes, 'image');
            preview(app.cam, im);
        end
        % Button pushed function: Button
        function ButtonPushed(app, event)
            img = snapshot(app.cam);
            image(app.UIAxes2, img);
            app.UIAxes2.Visible = 'off';
        end
    end
    % Component initialization
    methods (Access = private)
        % Create UIFigure and components

        function createComponents(app)
            % Create UIFigure and hide until all components are created
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.Position = [100 100 640 480];
            app.UIFigure.Name = 'UI Figure';
            % Create UIAxes
            app.UIAxes = uiaxes(app.UIFigure);
            title(app.UIAxes, 'Title')
            xlabel(app.UIAxes, 'X')
            ylabel(app.UIAxes, 'Y')
            app.UIAxes.Position = [26 270 300 185];
            % Create UIAxes2
            app.UIAxes2 = uiaxes(app.UIFigure);
            title(app.UIAxes2, 'Title')
            xlabel(app.UIAxes2, 'X')
            ylabel(app.UIAxes2, 'Y')
            app.UIAxes2.Position = [25 43 300 185];
            % Create Button
            app.Button = uibutton(app.UIFigure, 'push');
            app.Button.ButtonPushedFcn = createCallbackFcn(app, @ButtonPushed, true);
            app.Button.Position = [447 249 100 22];
            % Show the figure after all components are created
            app.UIFigure.Visible = 'on';
        end
    end
    % App creation and deletion
    methods (Access = public)
        % Construct app
        function app = app1
            % Create UIFigure and components
            createComponents(app)
            % Register the app with App Designer
            registerApp(app, app.UIFigure)
            % Execute the startup function
            runStartupFcn(app, @startupFcn)
            if nargout == 0
                clear app
            end
        end
        % Code that executes before app deletion
        function delete(app)
            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end

Error you are facing instantiates that the code is not able to access the camera object at that instant.

Hope it helps!!

MATLAB: How to add a live image to UIAxes in App Designer for MATLAB R2016b

The Image Acquisition Toolbox PREVIEW function does not support UIAXES in R2016b yet, but the toolbox team is aware of the customer need.

Best Answer

Related Solutions

MATLAB: App Designer: How to use a camera in different Callbacks

MATLAB: How to add a live image to UIAxes in App Designer for MATLAB R2016b

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