What can I do about ambient light?
While the brightness of today’s projectors overcome many adverse lighting conditions, picture quality does suffer as ambient light is flushed onto a projection screen. There are two ways in which to handle ambient light concerns:
- Reduce the amount of ambient light in the room.
Assuming you are utilizing a white or gray screen, the only way to deal with ambient light concerns it to actually remove the ambient light all together. Ideally, lights would be turned off, natural lights such as windows would be covered, and walls and ceilings painted a matte black color (see “Do I need an ALR screen in a dark room?”) to reduce light reflections from the screen surface to the walls, and back.
- Fight the ambient light with an ALR screen.
Our preferred solution, is to utilize an ALR screen technology such as Black Diamond or Slate which allow you to maintain some of the ambient light in the room, while also mitigating issues that arise with light reflections from the screen to the walls, and back. This also makes it possible to have a projection screen in places that had not been considered before such as a living room or other areas with ambient light.
SI has engineered the most advance screen solutions to address ambient light. Watch this video for more information about our different ALR technologies:
Do I need an ALR screen in a dark room?
In a completely dark room, your projector is its own worst enemy. What ever color is projected onto the screen at any given time is also reflected around the room, and then back into your image which can in turn negatively affect the screen image. Imagine projecting a red Ferrari onto a white screen. The reds created by the projector are reflected all over the walls, floor, and ceiling because the white material reflects the light in all directions. The red light is then reflected off of the walls, and back into the image creating a red color push. This issue persists with all colors emitted by the projector. Unless you have completely matte black walls, this is the case.
Black Diamond significantly reduces the light scatter created by the projector, therefore reducing the constantly changing color shift. It also rejects what color push may have returned from the walls thanks to its optical filtering technology. This results in much more accurate final image compared to a white or gray screen material.
Lastly the room color itself makes a color shift. If your walls are painted burgundy, you will notice a burgundy color push in your image. Black Diamond allows your walls to be painted with more colorful options and does not require a matte finish vs. a gloss or eggshell finish. This is extremely exciting because 99% of all theater rooms we encounter do “not” have color neutral walls. Watch this video to illustrate this concept:
A relatively recent attempt in improving the perceived image quality is the introduction of gray screens, which are more capable of darker tones than their white counterparts. A matte gray screen would have no advantage over a matte white screen in terms of contrast; contemporary gray screens are rather designed to have a gain factor similar to those of matte white screens, but a darker appearance. A darker (gray) screen reflects less light, of course – both light from the projector and ambient light. This decreases the luminance (brightness) of both the projected image and ambient light, so while the light areas of the projected image are dimmer, the dark areas are darker; white is less bright, but intended black is closer to actual black. Many screen manufacturers thus appropriately call their gray screens “high-contrast” models.
In an optimal viewing room, the projection screen is reflective, whereas the surroundings are not. The ambient light level is related to the overall reflectivity of the screen, as well as that of the surroundings. In cases where the area of the screen is large compared to that of the surroundings, the screen’s contribution to the ambient light may dominate and the effect of the non-screen surfaces of the room may even be negligible. Some examples of this are planetariums and virtual-reality cubes featuring front-projection technology. Some planetaiums with dome-shaped projection screens have thus opted to paint the dome interior in gray, in order to reduce the degrading effect of inter-reflections when images of the sun are displayed simultaneously with images of dimmer objects.
Gray screens are designed to rely on powerful image sources that are able to produce adequate levels of luminosity so that the white areas of the image still appear as white, taking advantage of the non-linear perception of brightness in the human eye. People may perceive a wide range of luminosities as “white”, as long as the visual clues present in the environment suggest such an interpretation. A gray screen may thus succeed almost as well in delivering a bright-looking image, or fail to do so in other circumstances.
Compared to a white screen, a gray screen reflects less light to the room and less light from the room, making it increasingly effective in dealing with the light originating from the projector. Ambient light originating from other sources may reach the eye immediately after having reflected from the screen surface, giving no advantage over a white high-gain screen in terms of contrast ratio. The potential improvement from a gray screen may thus be best realized in a darkened room, where the only light is that of the projector.