Digital booths
Why an image blend can look dark in ordinary sRGB math
Recognise when compositing or averaging needs linear-light values.
RGB numbers in a typical sRGB file are encoded for display; equal numeric steps do not correspond to equal increments of emitted light. If software averages, blurs or composites those encoded values directly, the result can differ from calculations performed in linear light. That can change edge blends, translucent overlays and gradients in a composite booth strip.
Choose the operation before the colour space
W3C’s colour specification separates gamma-encoded sRGB from linear-light sRGB and notes that linear spaces are appropriate when an operation should correspond to mixing light. Perceptually even transitions may call for a perceptual space instead. There is no one interpolation space that is best for every image operation, so identify whether the task is physical compositing or visual spacing.
Evidence: Web colour specification
Inspect a transparent edge
Place the same semi-transparent portrait edge or soft shadow over a dark and a light background using the production compositor. Compare the edge with a reference rendered in the intended colour space. A dark fringe or unexpectedly heavy blend can arise when alpha compositing is performed in an unsuitable encoding or with inconsistent premultiplication; confirm both settings before changing the portrait colours.
Evidence: Web colour specification
Keep export behavior consistent
Document the compositor’s working space and blending behavior alongside the booth template. Test gradients, translucent overlays and cutout edges after the final export and after reopening the file in the target viewer, because another application may interpret a profile differently. Do not simply label the output “linear”: deliver the correctly encoded file with a profile the receiving workflow supports.
Evidence: Web colour specification · Standards body technical guide
Sources & further reading
Sources for the specific facts and product descriptions above. Our worked examples, interpretations and practical suggestions are original editorial guidance.
- W3C CSS Color Module Level 4, colour interpolationWeb colour specification
- International Color Consortium, About ICC ProfilesStandards body technical guide