Colour Science & Perception
what the eye settles, and what it cannot
Generator

Three bounds on the same family, and three different worst cases

Four bars. The bottom one is the worst change of light on the census this collection has published for several rounds — 3.37 ΔE00, a list of fourteen. Above it, the worst found by searching the family that list was drawn from, under three nested bounds: the arithmetic box at 28.38, a reflectance a molecule could produce at 21.91, and a paint somebody sells at 21.91. The last two are the same number, because the purity ceiling never bites — the worst wall is dark rather than saturated. Beside each bar are the constraints its answer is sitting on, and none of the three bars sits in the interior of its own bound.
Three bounds on the same family, and three different worst cases. Four bars. The bottom one is the worst change of light on the census this collection has published for several rounds — 3.37 ΔE00, a list of fourteen. Above it, the worst found by searching the family that list was drawn from, under three nested bounds: the arithmetic box at 28.38, a reflectance a molecule could produce at 21.91, and a paint somebody sells at 21.91. The last two are the same number, because the purity ceiling never bites — the worst wall is dark rather than saturated. Beside each bar are the constraints its answer is sitting on, and none of the three bars sits in the interior of its own bound.

Drawn at its defaults, in a worst case, and the bound it is a statement about. It reads 1 option and no others: show.

Called by 6 essays

the blast radius of changing it

What light is

A notch a pigment cannot cut

The worst change of light a painted room can produce has no maximum inside the box the search was given, which the previous round reported as a family with no worst case. Bounded by what a molecule can actually do, it has one — at a band six nanometres wide, narrower than any pigment and narrower than the box.

 What a scene does

A room bounds its own bounces

The adaptation census has one bounce and two bounces as separate rows, and a search over the family treats the count as a free integer it always takes to the largest value offered. A room offers no integer at all — it applies a geometric mixture of every number of bounces, and that mixture is bounded by the walls reflecting less than everything.

 What a scene does

The darkest wall anybody sells

Asked which property of a paint decides the worst change of light a room can produce, anybody would answer how saturated it is allowed to be. A ceiling on saturation never comes near binding, because the worst wall is dark rather than colourful — and the constraint that does bind is one nobody would nominate.

 Where the model breaks

A mean is not a worst case

Every adaptation number this collection publishes is an average over objects, and the reader asking whether adaptation will fail them is asking about the object it fails on. That object costs between 1.9 and 4.0 times the published figure, and how uneven a change of light is across objects turns out to be a property of the change rather than a constant.

 Matching and measuring

An extremum is still not a sample

Two rounds ago three measurements turned up that took a maximum over a sample of a set and were short by up to a factor of two. The same error was live in a fourth place the whole time, on the set of surfaces every adaptation number is averaged over, and it is short by up to a third.

 What a scene does

Every worst surface sits on a declaration

Bounding the wall in a painted room produced a real worst case — the residual turns over at a band six nanometres wide because a narrower band returns too little light. Bounding the surfaces the residual is averaged over produces nothing of the kind, because all fourteen answers sit exactly on two numbers somebody typed and the one constraint that comes from the world never binds at all.

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