Color analysis quiz › Photo light check

Photo light check: is this selfie good enough for colour questions?

Warm indoor light, a window on one side, or an overexposed phone photo can change how a colour looks next to your face. This page reads the pixels you choose and reports four things — average brightness, clipped shadows and highlights, colour cast, and left-right evenness — before you use the photo for anything colour-related.

Runs entirely in your browser. Nothing is uploaded. The thresholds are heuristics, not standards.

Choose a photo

What the check reads

Measurement	What it means	A common cause
Average luminance	How bright the photo is overall (0 = black, 1 = white).	Evening indoor light; a dark room; underexposure.
Near-black / near-white share	The percentage of sampled pixels that are almost black or almost white.	Deep shadows behind you; a window or lamp blowing out the highlights.
Colour cast (R − B)	Positive means the photo reads warm (yellow/orange), negative means cool (blue).	Tungsten bulbs, a warm wall, shade with a blue sky.
Left vs right	The brightness difference between the two halves of the frame.	A window on one side; a lamp close to one cheek.

What it cannot tell you

It cannot see a beauty filter, a coloured wall behind you, or makeup.
It does not measure your skin, your undertone or your season.
A "usable" verdict does not make a photo colour-accurate; it only means the light is not obviously hostile.

If the photo fails

Move to indirect daylight, facing a window rather than sitting in direct sun.
Turn off the room light that is mixing with the daylight, or move away from it.
Take the photo straight on, with the whole face in frame, and no filter.
Run the check again. If it passes, use the colour quiz, and read what the evidence supports before treating the result as a rule.

FAQ

Is my photo uploaded?

No. The image is drawn to an in-page canvas and read pixel by pixel in your browser. It is not sent to the server and is not stored.

Does the light check tell me my season?

No. It only reports brightness, clipping, colour cast and left-right evenness. The season quiz asks about your colouring, and the result page explains what the evidence supports.

What are the thresholds based on?

They are heuristics chosen for this check, not published standards. The warm/cool threshold (0.12 on our R−B scale) is simply the level above which this page starts warning; it is not a measured point where every photo looks yellow. Treat the result as a prompt to retake the photo, not as a verdict about you.

What should a good photo look like?

Even daylight, no direct sun on the face, no strong coloured wall or lamp nearby, the whole face in frame, and no beauty filter. The check flags the most common problems; it cannot see a filter or a coloured wall by itself.