Use a USB camera to detect colors

Hello everyone! I have code that only recognizes the color white, and it works through the computer's camera. How can I change it to work with a USB camera?

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Program Name : white Object Detection and Tracking                      %
% Author       : Arindam Bose                                             %
% Version      : 1.05                                                     %
% Description  : How to detect and track white objects in Live Video      %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%% Initialization
thresh = 0.75; % Threshold for white detection
vidDevice = imaq.VideoDevice('winvideo', 1, 'YUY2_640x480', ... % Acquire input video stream
    'ROI', [1 1 640 480], ...
    'ReturnedColorSpace', 'rgb');
vidInfo = imaqhwinfo(vidDevice); % Acquire input video property
hblob = vision.BlobAnalysis('AreaOutputPort', false, ... % Set blob analysis handling
    'CentroidOutputPort', true, ... 
    'BoundingBoxOutputPort', true', ...
    'MinimumBlobArea', 400, ...
    'MaximumCount', 50);
hshapeinsWhiteBox = vision.ShapeInserter('BorderColor', 'Custom', ...
    'CustomBorderColor', [1 0 0]); % Set white box handling


hVideoIn = vision.VideoPlayer('Name', 'Final Video', ... % Output video player
    'Position', [100 100 vidInfo.MaxWidth+20 vidInfo.MaxHeight+30]);
nFrame = 0; % Frame number initialization

%% Processing Loop
while(nFrame < 300)
    rgbFrame = step(vidDevice); % Acquire single frame
    rgbFrame = flipdim(rgbFrame,2); % obtain the mirror image for displaying
    bwredFrame = im2bw(rgbFrame(:,:,1), thresh); % obtain the white component from red layer
    bwgreenFrame = im2bw(rgbFrame(:,:,2), thresh); % obtain the white component from green layer
    bwblueFrame = im2bw(rgbFrame(:,:,3), thresh); % obtain the white component from blue layer
    binFrame = bwredFrame & bwgreenFrame & bwblueFrame; % get the common region
    binFrame = medfilt2(binFrame, [3 3]); % Filter out the noise by using median filter
    [centroid, bbox] = step(hblob, binFrame); % Get the centroids and bounding boxes of the blobs
    rgbFrame(1:15,1:215,:) = 0; % put a black region on the output stream
    vidIn = step(hshapeinsWhiteBox, rgbFrame, bbox); % Instert the white box
    for object = 1:1:length(bbox(:,1)) % Write the corresponding centroids
        
    end
    step(hVideoIn, vidIn); % Output video stream
    nFrame = nFrame+1;
end

Answer 1

[Pravarthana P]

Hi Almog haviv, it can be understood that you are trying to detect white color through an USB web-camera.

Toolbox required : Image Acquisition toolbox

After connecting the USB web camera, you can find the following properties using the functions:

webcamlist– list of camera connected to the PC

imaqhwinfo – Information about the adapters

Once, after identifying the respective web camera use webcam([%corresponding web camera number]) to know about the web camera feature.

Replace “vidDevice = imaq.VideoDevice('winvideo', 1, 'YUY2_640x480')” with

vidDevice=videoinput(‘adapter name’,’device ID’,’format’);

By this you can use the created object vidDevice to detect any live streaming video input through USB webcamera.

Links you may find helpful:

• Webcam Image Acquisition - MATLAB & Simulink (mathworks.com)
• Using USB Webcams with MATLAB Online Video - MATLAB (mathworks.com)

Answer 2

[Image Analyst]

You need the Image Acquisition Toolbox, or you can probably get by with the simpler webcam utility. See the links @Pravarthana P gave.

To detect colors other than white, see my attached demo (that reads from a video file, not a live camera) that tracks a green Sharpie marker.