HD Waveform 10 - Dynamic Iris and Gamma

[Richard]

Over the last 3 years manufacturers have been busy improving their marketing specs to the mass market for contrast ratios by using an iris and gamma technique since better numbers creates the illusion of purchasing better performance. The purpose of this article is to put that into perspective so that the performance enthusiast will understand why this feature degrades overall image performance, why it sells product and why, for some technologies, it may be needed to be competitive.

<B>Iris</B>
One way to improve dynamic range and measured contrast ratio is to employ an iris. An iris typically decreases...

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[Richard]

Original

With the Dynamic Iris OFF at 96 lamp hours I obtained 367fl at 100IRE multiplied by .522fl for 0IRE yielding contrast ratio of 192.

With Dynamic Iris ON I obtained 715fl at 100IRE multiplied by .503fl for 0IRE yielding a contrast ratio of 360.

Edited

With the Dynamic Iris OFF at 96 lamp hours I obtained 367fl at 100IRE and .522fl for 0IRE yielding a contrast ratio of 703:1.

With Dynamic Iris ON I obtained 715fl at 100IRE and .503fl for 0IRE yielding a contrast ratio of 1421:1.

Original

The human eye is capable of about 800 based on being outdoors on a bright sunny day versus pitch black darkness. Does a real contrast ratio of 11000:1 have any value? If this could actually be delivered you would lose your eye sight very fast indeed! The point is this is nothing but specification marketing shenanigans that tell the consumer or imaging professional little about actual performance.

Edited

The human eye is capable of about 800:1 for any given scene whether on screen or in real life. Does a real contrast ratio of 11000:1 have any value? The point is this is nothing but specification marketing shenanigans that tell the consumer or imaging professional little about actual performance.