A projector screen can look worse than a white wall if its material rejects the projector’s light or sends it away from your seat. For a Hong Kong flat, choose by projector geometry, room lighting and surface flatness before paying for an “ALR” or “CLR” label.
Start with the white wall you already have
A smooth, flat, neutral white wall is a reasonable temporary baseline. It lets you judge image size and seating before committing wall space. It is not a purpose-made optical surface: tinted paint can affect colour, while unevenness can distort the image.
Use a familiar film scene and a straight-line test image at your normal viewing time. Check:
- Whether straight edges bend or the surface has visible bumps.
- Whether whites look tinted and pale areas show paint texture.
- Whether closing curtains or switching off a nearby lamp improves contrast.
- Whether the picture looks different from each end of the sofa.
If the wall is acceptable for occasional evening viewing, there is no need to buy premium material immediately. Compare any wall preparation cost with a screen, its installation and its storage needs.
White wall, white screen, ALR or CLR?
| Option | Useful starting point | Check before choosing |
|---|---|---|
| Neutral white wall | Temporary setup or occasional viewing | Flatness, paint colour and texture; room light remains a limitation |
| Matte white screen | A dedicated surface with broad seating flexibility | Material compatibility and tension; it does not selectively reject room light |
| Standard-throw ALR | Controllable stray light with a compatible projector position | Minimum throw ratio, reflection angle and sofa positions |
| UST-compatible light-rejecting screen | An ultra-short-throw projector with compatible light geometry | Exact material, permitted projector position and top/bottom orientation |
ALR and CLR are not universal compatibility labels
ALR means ambient light rejecting. Directional materials favour particular light paths; they cannot simply distinguish “picture” from “unwanted light”. A standard-throw ALR screen is therefore not automatically compatible with a short-throw or ultra-short-throw (UST) projector.
Elite Screens’ CineGrey 3D/4D/5D installation guidance excludes short-throw and UST projectors and requires suitable projector-to-viewer angles. Its older ALR comparison table uses broader category wording, so check the exact material instructions rather than one summary row.
Elite Screens uses CLR branding for ceiling light rejection; it is not a universal screen standard. Its fixed-frame comparison includes both UST products and standard-throw products carrying CLR names. Several Aeon CLR variants require projection from below. Do not assume every CLR material supports the same projector.
The Aeon CLR 2 manual explicitly identifies directional material and TOP/BOTTOM labels. Follow your own screen’s manual; do not reverse a screen or change projector mounting position based on generic advice.
Light direction matters too. A ceiling-light-rejecting surface may help with overhead lighting but perform differently with a side window. Strong light arriving near the projector’s angle can still wash out ALR. Direct sunlight is a reason to improve shading, not a problem a screen can be assumed to solve.
Read gain together with viewing angle
Gain describes reflected brightness in a specified direction relative to a reference surface. It is not an overall quality score. Depending on the material and geometry, concentrating light can increase brightness at one seat while narrowing useful viewing angles or increasing the risk of hot spotting: an unusually bright patch.
Check the manufacturer’s viewing-angle definition and brightness distribution. A wide sofa makes off-centre performance relevant. There is no universal “higher gain is better” rule, nor a gain number that guarantees adequate brightness in every dark or bright room.
Flatness and size must fit the actual installation
Flatness is particularly important with UST projection. BenQ’s support guidance for curved images on models including the V7050i highlights sensitivity to surface flatness and projection angle. A loose hanging sheet or curled pull-down screen can create a problem that buying ALR material does not remove.
Compare a properly assembled fixed frame with a tab-tensioned retractable option. Tensioning supports flatness; it is not a guarantee that every screen or installation suits UST. Confirm both the material and complete screen model.
A 100-inch, 16:9 image occupies approximately 221 × 125 cm. This is the display area only, excluding the frame, housing and mounting clearance. Measure the full product dimensions, cabinet depth, deployed height, doors, curtains and available power sockets where relevant.
Throw ratio relates lens-to-screen distance to image width, not diagonal size. Use your projector’s specified ratio and placement chart. For UST, also check vertical offset and the manual’s measurement reference: a rear-casing gap is not the same as lens distance. No single cabinet-to-wall distance works for every model.
Diagnose the symptom before changing material
| What you see | What to check first | Decision it helps you make |
|---|---|---|
| Bowed lines or ripples | Surface flatness and physical alignment | A flatter surface may matter more than light rejection |
| Picture washes out by day | Window and lamp directions; effect of curtains | Assess shading before selecting directional material |
| One bright patch or dim side seats | Gain, viewing cone and projector angle | Seek more suitable light distribution |
| New UST screen looks unexpectedly dark | Exact compatibility and orientation labels | Have the supplier or installer verify the pairing |
| Image will not fit the intended area | Supported image size, throw distance and offset | Resolve placement before ordering a larger screen |
Two hypothetical Hong Kong flat layouts
Layout A: a projector sits behind the sofa, facing a wall, with a bright window behind it. Window light travels towards the screen in a similar direction to the projected image. Start with curtains; a compatible standard-throw ALR material cannot be assumed to reject that light.
Layout B: a UST projector sits on a cabinet below the screen, with ceiling lights above and seating spread across the sofa. Consider a confirmed UST-compatible material and verify orientation, viewing angles and flatness. A side window still needs separate assessment. These are planning examples, not Elechid test results.
If daylight viewing remains the priority, our TV or projector guide for small Hong Kong flats helps with the wider decision.
What to confirm before ordering
- Projector model, intended screen size and mounting position.
- Exact screen model and material, including compatibility documentation.
- Photos showing the wall, windows, lights, cabinet and seating.
- Total cost including frame or housing, fitting, shading and storage.
In a rented flat, obtain permission before drilling. A freestanding option still needs suitable dimensions, stability and projector compatibility. Ask the screen manufacturer about unclear specifications. You can send Elechid the model details and room photos via WhatsApp to help identify what needs checking. Leave room for audio too; see our Sound Bar placement guide for small flats.
Frequently asked questions
Is a white wall always worse than a screen?
No. A suitable wall can be useful temporarily. An incompatible directional screen or poorly tensioned surface can introduce new problems.
Can I use any ALR screen with a UST projector?
No. Confirm the exact material and permitted projector position. “ALR”, “CLR” and “short throw” alone do not establish compatibility.
Will CLR remove all daylight glare?
No. Performance depends on incoming light direction and intensity. Control direct sunlight and assess side windows separately from ceiling lights.
Does a motorised screen guarantee a flat UST image?
No. Motorisation describes operation. Check tensioning, material compatibility and the manufacturer’s flatness and installation requirements.
The cover is an AI-generated concept illustration, not a measured comparison of picture quality or brightness.
Official sources
Checked on 6 October 2026. Manufacturer specifications apply to the named materials and models.
- Elite Screens: fixed-frame comparison, ALR comparison, angular-reflective guidance and CLR 2 manual.
- Elite Screens: gain and viewing terminology and ALR washout limitations.
- BenQ: screen selection, surface flatness, throw ratio and image area and placement measurements.
