getsnapshot function is leaving blank (all black) photos

Using Image Acquisition Toolbox, "getsnapshot" function is ending up with blank (all black) photos.

Yet, when I use preview(TopCam), the camera initializes and shows video properly.

My understanding is that, getsnapshot will turn on the camera, wait for video stream to begin, take a frame from this stream, and save it to memory, then terminate stream.

I am unsure where the black or blank photo data is coming from.

Below is my code and output:

TopCam = videoinput('winvideo', 2, 'MJPG_4096x2160');
TopImg = getsnapshot(TopCam);
image(TopImg);

[Siddharth Bhutiya]

What camera are you using?

Could you try doing getsnapshot 5-6 times in a row and see if that gives you the image. Some cameras have a warm up period that it takes, before returning proper images.

[Anthony Zand]

Hello,

I am using three logitech Brio webcams.

I just wanted to follow up on my problem! I was able to get the code to function properly by performing a complete restart of the PC and camera configuration. The problem is reproducable and seems to lie when the PC is placed in a standby or sleep mode, all three webcams would not function properly when awoken with this script.

The restart had fixed it, I am unsure which settings may cause for this to occur but I believe this issue is outside of MatLab space, and in the PC configuration space.

Answer 1

[Cris LaPierre]

What error messages are you getting? I obviously don't have the same hardware as you, but on my computer, this code works. Note that the camera id is in single quotes, and i have to start the camera.

TopCam = videoinput('winvideo', '1');
start(TopCam);
TopImg = getsnapshot(TopCam);
stop(TopCam)
image(TopImg);

[Cris LaPierre]

Of course, now that I got it working once, it runs even if I strip the code back down to your original code. Still, the first time, I did get a black screen just like you.

[Anthony Zand]

Thanks for the follow up, in my other comment I replyed how I was able to resolve the issue. However, if I do run into my problem again, I will try this method. I see how the implimentation of start(TopCam) would wake the device out of the standby state it is in and resolve the problem. Thank you!