Screen gain is part of the projector's light budget.
Screen gain describes how much light a screen reflects toward the viewer compared with a reference diffuse white surface. A nominal 1.0 gain screen is the baseline. A 1.3-gain surface can deliver more on-axis luminance; a 0.7-gain surface intentionally returns less.
That number matters because the projector does not create nits in isolation. Final screen luminance depends on calibrated lumens, image area, screen gain, lens losses, throw, zoom position, optical transmission and the screen's real behaviour at the seating angles.
Matte white: the reference starting point.
A high-quality matte white screen around 1.0 gain is often the cleanest baseline for a fully light-controlled cinema. It generally offers a very wide viewing cone, neutral colour behaviour and excellent uniformity. Stewart's StudioTek 100, for example, is a unity-gain matte white material designed as a near-Lambertian diffuser.
The trade-off is that it reflects light broadly — including light that bounces off pale walls and returns to the screen. In a bright room, the screen cannot distinguish projector light from room reflections.
Higher-gain white surfaces: more luminance, with geometry consequences.
A surface such as a 1.3-gain material can materially increase on-axis brightness. Stewart describes StudioTek 130 G4 as roughly 30% brighter than a matte-white reference. That can be extremely valuable for HDR, large screens or lower-output projectors.
But gain is not free light. Higher gain usually narrows the viewing cone and can make hot-spotting, sparkle or angular colour/brightness shifts more apparent. Projector throw and seating geometry should therefore be checked against the material rather than selecting gain only from a calculator.
Grey screens: deliberately trading luminance for black-floor control.
Neutral grey materials reduce reflected light. A 0.7-gain grey surface returns roughly 70% of the reference on-axis light, which can help tame an over-bright projector or improve perceived black level where some ambient or reflected light remains. Stewart's GrayMatte 70 is a real example of this approach.
In a truly black dedicated cinema, a grey screen is not automatically better: you may simply be throwing away precious HDR luminance. It is a system choice.
Acoustically transparent screens change the calculation.
Putting the LCR speakers behind the image is often the right architectural and acoustic solution, but every acoustically transparent surface makes a compromise between light transmission/reflection, acoustic transparency, texture and moiré visibility.
Woven fabric
Sound passes through the physical weave rather than drilled holes. Good woven materials can provide very natural acoustic behaviour and avoid perforation moiré, but some projected light passes through the weave. Stewart's own Harmony G2 testing reports about 0.7 on-axis gain, illustrating how a woven AT screen can require significantly more projector light.
Perforated vinyl
A conventional coated screen surface is mechanically perforated so sound can pass through. It can retain the optical characteristics and higher gain of familiar screen coatings, but the perforation pattern, viewing distance and projector pixel structure must be considered.
Micro-perforated
Smaller and denser perforations can make the hole structure less visible from closer seats. The trade-offs include acoustic attenuation at higher frequencies, possible moiré interactions and some light loss through the open area.
Solid non-AT surface
Usually gives the designer the greatest freedom in optical coatings and gain because no light is intentionally passing through holes or weave. The compromise is that screen speakers cannot sit directly behind the image.
Why the black backing behind a woven screen matters.
Light that passes through an AT weave can illuminate speakers, timber, insulation or the wall behind the screen and then scatter back through the fabric. A black backing layer or blacked-out screen wall helps prevent this. It can also add some acoustic attenuation, so the audio system should be calibrated with the complete screen assembly in place.
Perforated vs woven is not a philosophical choice.
For a 5-metre screen with enormous projector headroom, a low-gain woven surface may be perfectly sensible. For a projector already working near its maximum light output, moving from a 1.0 or 1.3 material to a 0.7 woven fabric can materially reduce HDR headroom. Conversely, a high-gain perforated vinyl may create viewing-angle or texture issues in a short, wide room.
If a screen material changes effective gain from 1.0 to 0.7, the projector has effectively lost about 30% of its on-axis light at the screen. You may need more projector, a smaller image, a different operating target or a different material.
Screen colour, coating and ambient-light rejection.
White, grey and optical/ALR surfaces should not be grouped only by colour. Directional coatings can redirect light toward the audience and reject light arriving from other angles. That can be useful in media rooms, but in a fully dark cinema it may introduce compromises that a simpler diffuse material avoids.
For RGB laser, test the actual material.
Narrow-band laser light can expose screen characteristics differently from laser phosphor or lamp sources. Speckle, sparkle, colour uniformity and viewing angle should be assessed with the intended projector class whenever possible.
What should be in the screen/projector calculation?
- Actual image width and aspect ratio
- Calibrated projector output, not only brochure lumens
- Lens and zoom-position transmission losses
- Screen gain and seating viewing angles
- Acoustically transparent light loss / backing layer
- Target SDR and HDR luminance
- Room reflectivity and ambient light
- Laser ageing / operating headroom
Screen references: Stewart — What is gain? · StudioTek 100 · StudioTek 130 G4