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

Two reflectances the camera records as identical

Constructed by projecting onto the null space of the sensor's own sensitivities, so the two raw triples agree to 0.0000 per cent. To the eye they are ΔE00 15.33 apart, which the swatches show.
Two reflectances the camera records as identicalConstructed by projecting onto the null space of the sensor's own sensitivities, so the two raw triples agree to 0.0000 per cent. To the eye they are ΔE00 15.33 apart, which the swatches show.400450500550600650700wavelength / nmtwo reflectancesas the eye sees themRGBas the camera records themraw gap 0.0000%, ΔE00 15.33null space of the sensor

Drawn at its defaults, in cameras, sensors and reproduction. It takes no options at all, so every essay calling it gets this exact drawing.

Called by 3 essays

the blast radius of changing it

What a camera does

Luther said when it would work

There is an exact condition under which a fixed three-by-three matrix converts camera raw to XYZ correctly for every spectrum in existence. It was stated in 1927, it is a theorem rather than a guideline, and no camera ever built satisfies it.

 What a camera does

The camera has its own metamers

Two surfaces a camera records as identical can be plainly different to a person, and two a person cannot tell apart can be recorded as different. Both pairs are constructed rather than found, from one projection, used for both.

 What a camera does

No matrix is right everywhere

The best three-by-three this sensor admits, fitted and tested on the same twenty-four surfaces, leaves a worst case of ΔE00 2.85. A control sensor built to satisfy Luther's condition reaches ten to the minus seven under the identical computation, which is what makes the first number a measurement.

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