A screen that looks clear in a design review can become a mirror beside a window, stage light, or glossy cover. The useful approval question is simple: can a first-time visitor read the instruction, identify the next control, and understand the result from the positions the installation actually permits? Check this after the screen is mounted, because the reflection depends on the display, cover, light sources, and viewing angle together.
The Smithsonian Guidelines for Accessible Exhibition Design specifically call for eliminating glare on interactive instruction surfaces and considering reflections from seated, shorter, and standing visitors' viewpoints. That is an exhibition-design reference, not a universal brightness specification for an outdoor commercial display.
Use design contrast as the starting point
For a browser-based interface, apply the relevant WCAG 2.2 text contrast criterion to the actual foreground and background colors. The criterion establishes a digital content baseline; it cannot see a reflected spotlight on the installed screen. W3C's explanation notes the role of ambient light in perceived display contrast. Passing a color-pair checker therefore does not remove the need for a physical viewing test.
The installed viewing test is therefore its own approval step. The Smithsonian's exhibition guidance also calls for checking reflections from both seated and standing positions; a single screenshot cannot capture those angles. Neither reference establishes one display brightness that works across all venues.
Make a viewing map, then read the task
Mark where a visitor is likely to stand or sit while noticing the screen, starting the interaction, and reading the result. Include the edge of any queue and the approach direction. At each position, test the smallest necessary text, the primary button, a selected state, an error message, and the final answer. Test with the actual protective glass or film and the intended mounting angle. A screenshot taken straight on is useful evidence of content, but it can miss glare visible only from the side.
For an outdoor or window-facing setup, repeat at the expected time of day or under a credible lighting simulation. For an indoor show, repeat with stage lighting, booth lighting, and any dimmed show state. The organizer and venue team should agree who can move a fixture, adjust a shade, change the display angle, or revise the content before opening. Each proposed fix should be tested again from the same viewing positions.
Some fixes are physical: rotate the station, shield an overhead reflection, move a light, or change the cover. Some are editorial: shorten a dense instruction, enlarge the key label, and avoid placing essential text over moving imagery. Increasing the screen's brightness alone may not cure a sharp reflection or a viewing-angle problem. Treat these as testable options, not universal display rules.
Record a pass condition
Ask a first-time tester to complete the task without coaching while an observer notes every missed instruction or control. Repeat with someone seated and from the queue side. Record the light setup, screen angle, and content version so a later venue adjustment does not silently invalidate approval. If the screen will tour, rerun this test at each location; the touring installation guide explains why the same core build needs venue-specific checks.
The general accessible touchscreen brief includes reach, timing, input, and physical access. This lighting test has one narrower outcome: the installed display communicates the essential task from every intended viewing position in the light visitors will encounter.