how to find images completely white?

I have checked that a lot of images in a website are completely blank, ie, 500x500 with all pixels white. All the images are in subdirectories of the images directory. How can I check which ones are white? I am thinking on getting the names of these images. **UPDATE**: - I would like to use some bash script or command. - Imagemagick is installed - Server is Ubuntu 14.04 - All images are .jpg extension