PS-REP-148 · r2 REPRESENTATION OBSERVED ENGAGED

DARK-ADAPTED CONTRAST LIMIT

The contrast that makes a signal readable is the same contrast that wears the eye down.

01 DEFINITION

Condition in which the contrast needed to read a display and the contrast an eye can sustain across a long continuous shift move in opposite directions, in an environment kept dark so that adaptation holds.

02 CONDITIONS

UNCERTAINTY MISSING The margin between readable and fatiguing is not given by any specification; it has to be found.

TIME PRESSURE SUSTAINED The cost accumulates across a whole shift rather than arriving with any one reading.

ERROR ASYMMETRY DEFERRED Getting it wrong shows up hours later as degraded acuity, not as a single item missed.

OPERATOR STATE DEDICATED The operator reads the same surface for the length of the shift and has no second task to break the exposure.

03 WHERE IT APPEARS

MARITIMEA judgement made by ear has to survive being redrawn as a trace on glass.

MEDICALA waveform is shown to someone who was trained to listen for it.

ENERGYA slow drift is plotted at a scale on which slow drift looks flat.

AVIATIONThe instrument is exact, and what it is exact about is not what is being asked.

04 WHAT AEON WORKED THROUGH HERE

The requirement was a display that stays readable through a long unlit shift. Lowering everything uniformly met it and was wrong — it flattened the distinctions that mattered along with the glare. The work went into which elements are allowed to keep their contrast, and into what decides that rather than who negotiates it.

The question it keeps returning to is where the contrast floor sits once the eye has been adapted for hours — not at the start of a shift, when every choice still looks acceptable.

05 LINKED TERMS

PS-DET-016 ATTENTION NARROWING PS-LOD-102 FATIGUE ACROSS LONG SHIFT PS-REP-149 RENDER-LIMITED DETAIL LOSS PS-REP-150 SINGLE-CHANNEL DISTINCTION