Exposure compensation is a button, or dial option on almost all camera bodies. Have you ever wondered what it's for?
When you point your camera at a scene, your camera meters all the light in the frame and formulates an exposure at a middle gray tone. Middle gray tones work great for most mainstream photographs, however your camera gets tripped up if the subject your photographing is black or white. Your camera always forces the exposure to record a middle gray tone, which is why your snowy photographs are light gray; not white and your black lab is sort of dark gray; not black.
Here are two examples and a tip on how to fix the problem even if you shoot in auto mode!
The second image above is how my camera metered this scene with no exposure compensation. My black top is gray and it completely blew out my white door. The camera's sensor had no idea what to do. I helped it out in the first example only by dialing my exposure compensation down to -2. Once I forced the camera to record a true black, even the white door become properly exposed.
Once again, my camera's sensor got confused by the white and wanted to bring that white down to "standard gray". With just one adjustment, you can assist your camera to record a true white. I increased the exposure compensation by +2 for the first image.
Hey! If you feel like giving it a try, attach your results. I'd love to see what you come up with. If you have questions, let me know!