How do I get images from multiple cameras at the same time?

I'm trying to get images from 2 cameras at the same time. But this codes doesn't show and save capture images but only show video previews of two cameras.

Error message is below

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Error using imageDisplayValidateParams>validateCData (line 117) Unsupported dimension.

Error in imageDisplayValidateParams (line 31) common_args.CData = validateCData(common_args.CData,image_type);

Error in imageDisplayParseInputs (line 79) common_args = imageDisplayValidateParams(common_args);

Error in imshow (line 198) [common_args,specific_args] = ...

Error in time_capture_jh2 (line 30) imshow(img1)

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My code is below

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 function [ output_args ] = Untitled1( input_args )

%UNTITLED1 Summary of this function goes here
%   Detailed explanation goes here
%vid=videoinput('winvideo',2,'yuy2_640x480')

vid1 = videoinput('winvideo', 1, 'yuy2_640x480'); 
vid2 = videoinput('winvideo', 2, 'yuy2_640x480'); 

triggerconfig(vid1,'manual');
triggerconfig(vid2,'manual');

set(vid1,'returnedcolorspace','rgb');
set(vid2,'returnedcolorspace','rgb');

set(vid1,'framespertrigger',10);
set(vid2,'framespertrigger',10);

set(vid1,'triggerrepeat',inf);
set(vid2,'triggerrepeat',inf);

start(vid1)
start(vid2)

for ctr = 1:1000

trigger(vid1); trigger(vid2);
preview(vid1); preview(vid2);

img1 = getdata(vid1);
imshow(img1)
fname = ['1003_400' num2str(ctr) '.jpg']; % make a file name
imwrite(img1, fname, 'jpg'); 

img2 = getdata(vid2);
imshow(img2)
fname = ['1003_200' num2str(ctr) '.jpg']; % make a file name 
imwrite(img2, fname, 'jpg'); 

pause(1800)
%pause(1800);  

end 
stop(vid1)
stop(vid2)

Answer 1

[dk]

The error message has nothing to to with using 2 cameras. Your FramesPerTrigger setting is 10. so img1 and img2 will be 4-D matrices, where the fourth dimension is the frames. This is also covered here:

http://www.mathworks.com/matlabcentral/answers/45838

Try following in the FOR loop to see what I meant; obviously, this will only save the first of every block of frames you captured with getdata():

imshow(img1(:, :, :, 1));
imwrite(img1(:, :, :, 1), fname, 'jpg');

Also, for speed reasons, you probably don't want to call imshow() in the loop, but call it once outside the loop to pre-generate the image:

himg = imshow(zeros(480, 640, 3)); % returns the handle to the image

then in the FOR loop, just update the image data using the image handle

set(himg, 'Cdata', img1(:, :, :, 1)); % instead of imshow(img1(:, :, :, 1))