Two cameras real-time on parallel processor errors

I am trying to process two camera images on real-time and parallel. I wanted to start with camera image acquisition on parallel workers and just display the raw images real-time. The last "spmd" block gives the error

"Cell contents reference from a non-cell array object"

apparently I don't do the legal variable assignment in the parallel block. I tried "parfor" in order to make a loop to grab images, but this time I got the error saying:

"It is illegal to use a composite within the body of a parfor loop"

Could you please suggest a legal way of grabbing two camera images at the same time in a loop from two parallel workers?

% this version is dedicated for showing the video real-time

clear all
close all
clc

%% Create a parallel pool with two workers, one per camera

if isempty(gcp('nocreate'))
    parpool(2)
end

%% Disconnect from all cameras from main MATLAB process and workers
delete(imaqfind);
spmd(2)
    delete(imaqfind);
end

spmd(2)

    for idx = 1:2%numlabs
        if idx == labindex
            imaqreset
            
            % Detect cameras
            gigeinfo = imaqhwinfo('gentl');
            numCamerasFound = numel(gigeinfo.DeviceIDs);
            fprintf('Worker %d detected %d cameras.\n', ...
                labindex, numCamerasFound);
        end
        labBarrier
    end
    
    cameraID = labindex;
    v = videoinput('gentl', cameraID);
    s = v.Source;

end

figure,
spmd(2) %number of cameras
    
    for(j = 1:100) %number of frames

        img = getsnapshot(v);
        img1 = img{1};
        img2 = img{2};
        img2 = imresize(img2, size(img1));
        
        frames_12 = cat(2, img1, img2);
        imshow(frames_12);
    end
end