When you're thinking about safety projection systems, it’s tempting to focus on brightness. After all, more lumens must mean better visibility… right?
Not quite.
In this article, we’ll break down what Lux really means, how it affects visibility, and why getting it wrong can lead to wasted money—or signs that people can’t actually see.
Let’s get technical for a moment.
Lux (lx) is a unit of illuminance:1 Lux = 1 lumen per square metre.
Unlike lumens, which measure how much light a projector emits, Lux tells us how much light actually lands on a surface.
This matters because your sign is competing with the surrounding light in the environment. Think of it like trying to see your phone screen:
In a dark room? Super bright.
In direct sunlight? Practically invisible.
Your eye perceives contrast, not just brightness. That’s why a 20W LED projector that looks brilliant in a dark hallway might be completely washed out in a sunlit loading bay.
Every projected sign involves a few key ingredients:
Lumens = total light output
Beam angle = how wide or focused the light is
Throw distance = how far the light travels
Surface reflectance = how much light the surface reflects back
Ambient Lux = how much light is already in the space
Here’s where it gets tricky:
High Lux + long throw distance + light-colored surfaces = poor contrast.
We’ve seen it time and again: same projector, same power, wildly different results depending on the environment. That’s why we design against the worst-case scenario—not just hope it works.
Let’s walk you through what happens in real-world lighting conditions.
Scenario 1 – 0 Lux (Pitch Black)
In total darkness, your retina is wide open, hungry for light. The red wavelength from the projector pops—vivid, saturated, unmistakable. Maximum contrast.
Scenario 2 – 60 Lux (Moderately Lit)
Now there’s a bit of ambient light. Your eyes adjust, and the red still shows up clearly, but it’s already competing with its surroundings. Contrast starts to fade.
Scenario 3 – 180 Lux (What we would class as a "dark" Industrial Environment)
The same projector now appears dull and desaturated. Not because it’s emitting less light, but because your eyes are adapting to the brighter environment. It’s called luminance masking—and it makes even strong signs disappear into the background.
Scenario 4 - Anything over 200 Lux (A standard bright warehouse)
Here’s where it starts to get difficult.
We hear this all the time:
“Can’t you just recommend a projector for our warehouse?”
And we get it. You want fast answers. But here’s the reality:
Without knowing your Lux level, any quote is guesswork.
And guesswork leads to:
Overpowered systems (you spend too much)
Underpowered systems (people can’t see the sign)
That’s why we don’t just “sell projectors”—we design safety outcomes. Our process involves real photometric planning—matching Watts, Lumens, Lux, throw distance, and surface reflectance to get it right the first time.
Here’s how to get it right:
1. Use a reliable Lux meter
We recommend:
2. Measure at the right time and place:
When your space is busiest
With all lights, skylights, and shutters open
At the exact surface and height where the projection will go
We then calculate the relevant projector for your worst-case Lux level to guarantee you can always see the sign we offer you.
Here’s what we typically recommend based on ambient Lux:
| Ambient Lux | Recommended Projector | Common Use |
|---|---|---|
| 0–60 Lux | 20W LED | Dark corridors, enclosed areas |
| 60–150 Lux | 25W LED | Internal walkways, dim warehouses |
| 150–250 Lux | 50W+ LED | Bright loading bays, sky lit areas |
| 250+ Lux | 100W+ LED | Areas near doors, or directly under skylight |
Read this article to understand what to expect it to cost for your factory: How much do LED shop floor marking Projectors cost and what factors affect the price?
We also factor in:
Mounting height & angle – Poor angles reduce intensity and distort the image.
Surface color – White reflects light well; grey or green? Not so much.
Motion zones – Busy areas often need stronger contrast or animated projection.
Temperature range – Our projectors operate from -40°C to +60°C, rain or shine.
Too many suppliers will sell you a projector without asking the right questions. That’s not how we work.
At Clarity, we use data—Lux readings, optical science, and real-world conditions—to ensure your safety signs don’t just “look nice,” but actually get seen when it matters most.
Want to talk through your site’s lighting conditions, or actually test a projector at your site?