How to use multiple user input variable?

Hello everyone,

I want you to help me how to solve this appeared error when i run this code.

First, i want to use video capture from web.

2. And then i want to ask: Do you want to save image from webcam?

3. I want to input dialog box for input variable (ImageName, Num_images, Start_num_Im).

4. And the i want to write this capture images to database with this input variables.

Please help me how to solve appeared error.

Thank you very much.

for my sample code:

clear all
close all
clc

% Create the webcam object.
cam = webcam(1, 'Resolution','640x480');
preview(cam);

count = 0;

promptMessage = sprintf('Do you want to capture frame from webcam?');
button = questdlg(promptMessage, ...
        'Save individual frames?',...
        'Yes', 'No', 'No');
        hold on;
        
%compare the string
if strcmp (button, 'Yes')
    
    x = inputdlg({'Name','Number_of_images','start_number'},...
              'Please enter the Imageinfo', [1 20; 1 20; 1 20]);
    videoFrame = snapshot(cam);
    figure, imshow (videoFrame);
    
    %this is where we will be save face image
    baseDir = 'C:\Program Files\MATLAB\R2018a\bin\testimages\' + Name;
            
    % Finally, create the folder if it doesn't exist already.
    if ~exist(baseDir, 'dir')
        mkdir(baseDir);
    end
    
    %baseName = image
    baseName = join(baseDir + num2str(start_number) + '.jpg');
    
    %check exit file or not!
    while Num_images < Number_of_images
        Num_images = count + 1;
        baseName = join(baseDir + num2str(start_number) + '.jpg');
    
        Iresize = imresize (videoFrame, [500 500]);
        imwrite (Iresize, baseName);
        
        %figure();
        imshow (Iresize);
        title ('Capture image');
    end
    
    elseif strcmp (button, 'No')
       disp ('Ok! close all');
       closePreview(cam);
       clear cam;
end

[Rik]

• Replace clear all with clear or clearvars. Or even better: use functions to keep your workspace clean. Don't ignore the warning mlint is giving you.
• Don't use close all. Maybe your user has useful GUIs or figures open. You aren't shutting down Matlab or the computer at the end of the code either. You should be using explicit handles to a figure so you can close that figure at the end of your code.
• You don't print anything to the command window, so why are you calling clc?

You didn't mention which line is triggering an error, and what the full error message is.

Answer 1

[Subhadeep Koley]

Alex, the below code might help! Have a look.

% Create the webcam object.
cam = webcam(1, 'Resolution', '640x480');
preview(cam);

promptMessage = sprintf('Do you want to capture frame from webcam?');
button = questdlg(promptMessage, 'Save individual frames?', 'Yes', 'No',...
    'No');

% Compare the string
if strcmp (button, 'Yes')
    x = inputdlg({'Name', 'Number_of_images', 'Start_number'},...
        'Please enter the image info', [1 20; 1 20; 1 20]);
    name = x{1};
    numberOfImages = str2double(x{2});
    startNumber = str2double(x{3});
    
    % Paste your dir path here
    baseDir = 'C:\testImages\';
    
    % Finally, create the folder if it doesn't exists already
    if ~exist(baseDir, 'dir')
        mkdir(baseDir);
    end
    
    figHan = figure;
    axHan = axes(figHan);
    
    for idx = 1:numberOfImages
        videoFrame = snapshot(cam);
        imshow(videoFrame, 'Parent', axHan)
        title(['Frame number: ', num2str(idx)])
        videoFrame = imresize(videoFrame, [500, 500]);
        baseName = [baseDir, name, num2str(startNumber), '.jpg'];
        imwrite (videoFrame, baseName);
        startNumber = startNumber + 1;
    end
    
    clc
    disp ('Done!')
    closePreview(cam)
    clear cam
    
elseif strcmp (button, 'No')
    disp ('Ok! Closed all');
    closePreview(cam)
    clear cam
end

[Rik]

This code is closing all other figures, even if the user chooses not to capture the frames. It also opens a large amount of figures (numberOfImages), instead of updating the CData property of the image object. This will result in slow code that you can't leave in the background because of the constant poping up of figures.

[Subhadeep Koley]

@Rik Thanks for the suggestions! The code is not by no means an optimized one. I provided that code snipped just as an example. I've edited the answer to incorporate the suggestions.

[Alex Zai]

Great! That's help to me. Thanks for your answers.

I have another question, pls. In this code, if input value for x isempty (user din't entered nothing ), can i use this?:

if isempty(x)
        disp ('You did not entered the input values');
        closePreview(cam)
        clear cam
    end

I added after input dialog bo and tried. But it still running loop and appered error. How can i fix this pls?

Have a great day!

[Rik]

If you have this as a function you could use return at the end of the if section. Unfortunately you are now forced to put the rest of your loop in the else section.

Another strategy would be to put the actual code in a try part, and put this in the catch block. Then you can trigger errors in places you need to exit the code. That way you don't need to copy and paste that code many times.