Building the Ideal Audiovisual System: Sensitivity, Dynamic Range and Color

It is the mark of an educated mind to be able to entertain a thought without accepting it — Aristotle

In the last chapter, we looked at camera and display sizes, resolution and frame rates. In this part we’ll look at Sensitivity, Dynamic Range and Color.

Ideal2

Sensitivity

The Camera must be equally sensitive from ISO 1 to 800. As a matter of practical utility, there is no barrier for a sensor to go beyond ISO 800 as long as 100% perceptible signal to noise ratio is maintained.

Dynamic Range

The Ideal Camera

The dynamic range of the human eye is 20 stops (1,000,000:1), and a camera must be capable of this, as a minimum. The ideal sensitivity would be 30 stops.

The camera sensor must be capable of a perfectly linear gamma ‘curve’. Log Gamma is acceptable as an addition, as are other ‘profiles’ for aesthetic reasons. Such a camera will have a middle grey value of 50% (linear) and 3.3% (log).

The Ideal Display

In the real world, the contrast range is in the order of 30 stops, and the ideal display must be capable of 30 stops to account for light pollution.

Such a display will be able to recalibrate itself by reading ambient lighting conditions to produce imagery within the 20 stop region conducive to the human eye. This display can be used both in fully dark environments as well as cloudless noon outdoor conditions at the equator.

In order to fulfill this, the display must be able to show imagery from 1 nit (cd/m2) to 40,000 nits (cd/m2).

The display must be capable of matching the gamma characteristics of the human eye, and must be capable of both linear and log RGB gammas. The gamma curve will be automatically determined by the display based on ambient conditions. The display will be capable of making changes on a single pixel basis.

Furthermore, the display must be able to account for contrast sensitivity, and increase contrast accordingly when frequency of detail increases.

Color

The ideal sensor should not be a Bayer sensor, but must offer full RGB per individual pixel, in a gamut corresponding to CIE XYZ (Practically tested regularly based on the latest advancements). In this respect, it is an unnecessary complication for it to imitate the eye.

A display must map this gamut precisely.

The color bit depth of the display or camera need only be 8-bits to take in all the 10 million colors the human eye can possibly see.

The standard white point will be D65, corresponding to 6500K. The sensor will be capable of a color temperature from 1000K to 30,000K.

The color information will be fully sampled, with zero sub-sampling in any channel. Neither sensor nor display must be unequally sensitive to any wavelength of light, and must be able to cleanly filter out any wavelengths outside the visible spectrum.

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