Inside the booth
Measure dark corners before correcting booth-image vignetting
Corner darkening can come from the lens, lighting or an obstruction.
If faces near the edges look darker than the center, avoid applying a global brightness increase straight away. First find whether the unevenness follows the lens, the light or the room.
Photograph a uniform target
Capture a plain matte wall evenly lit at the booth position. If the corners darken in the same pattern after the light is moved, lens vignetting or a lens accessory may be responsible. If the pattern follows the lighting, adjust source placement or diffusion instead.
Evidence: Optics engineering guide
Check for mechanical obstruction
Inspect the lens hood, case, filter and mount for anything intruding into the field of view. On a phone, confirm that fingers or a protective cover do not shade one corner. Repeat the test after removing only a safe, user-removable obstruction. Edmund Optics distinguishes blocked rays within the optical system from other illumination variation; an accessory or lens format mismatch can darken the outer field.
Evidence: Optics manufacturer application note
Correct and verify
Apply a lens profile only when it matches the camera and lens state. Corner lifting can raise noise and change colour, so check the final strip at its print size. Keep one original capture and record whether the correction came from lens software or a lighting change.
Evidence: Optics engineering guide
Sources & further reading
Sources for the specific facts and product descriptions above. Our worked examples, interpretations and practical suggestions are original editorial guidance.
- Edmund Optics, Sensor Performance and LimitationsOptics engineering guide
- Edmund Optics, Optics Application ExamplesOptics manufacturer application note
- Edmund Optics, Imaging Optics Resource GuideOptics engineering guide