There is another application which can be used to capture the images from the webcam named as Fswebcam. you can install that with
sudo apt-get install fswebcam
you can have a sample shot with the following command.
fswebcam -r 640x480 --jpeg 85 -D 1 web-cam-shot.jpg
In the above code syntax ,
-r stands for Image resolution ,
--jpeg stand for format type of the image &
85 for its quality standard,
-D stands for delay set before capture.
Now your image finally saved with web-cam-shot.jpg name.