There are two kinds of screen materials widely used for home theater: traditional white and light to medium gray. The concept of the gray screen was first introduced in 2001, and gray screens have become immensely popular ever since. Gray screens are sometimes called high contrast screens. The main purpose of a gray screen is to boost contrast on digital projectors in viewing rooms that are not entirely dark. The gray screen will absorb unwanted ambient light that strikes it much more efficiently than a white screen does.
By absorbing light pollution in less than ideal conditions, the black level on the screen is maintained. The end result is that the contrast range of the image on the screen is enhanced. If you have a home theater room dedicated to that purpose only and can achieve total darkness, a white screen is your best bet. If however you have your HT set up in a multipurpose room with windows and doors that create imperfect dark condition, which is what most people have , the gray screen will generally give you a much better picture quality with sharper contrast.