Rasberry PI camera error

I am connecting my raspberry pi2 to matlab in order to do some image processing. However, when I run the following commands all I get is a black screen. I know the issue is not the camera because I tested it on the pi os and it gives me pictures just fine. Please help.

The code is:

mypi=raspi();
myCam=cameraboard(mypi,'Resolution', '640x480');

mySnap=snapshot(myCam);
imshow(mySnap);
hold on

Here is a picture of the screen:

[Walter Roberson]

what is min(mySnap(:)) and max(mySnap(:))

[Dennis]

min(mySnap(:)) is 0 and max(mySnap(:)) is 217

Answer 1

[Krishna Moorthy]

Increase the brightness by the command cam.Brightness = 70. You shall get the image..