[Bf-compositor] Clamping (Mix, Math, RGB Curves)

[Troy Sobotka]

On May 23, 2014 9:12 AM, "Sean Kennedy" <mack_dadd2 at hotmail.com> wrote:

>  It made sure that no matter what a compositor did, the blacks wouldn't
go too dark and the brights would never get superbright.

When _working_ in the scene referred HDR domain, there is no notion of
superbright. It is precisely why lift, gamma, and gain doesn't work on
scene referred data.

When transferring to the display referred system at the tail end, it is
necessary to assign a scene referred value to display referred RGB = 1 as
diffuse white, and scale the scene referred data to it.

My only concern is assuming that 1.0 has any meaning while doing the bulk
of the work in the scene referred model. It doesn't. It would _always_
limit one's working model to ~2.5 stops of latitude, which is rather silly.

A flexible clamp node however would be excellent assuming it is versatile
and can be used on a full range of scene referred / HDR values. Even a
clamp / scale node that allows an artist to scale values arbitrarily to
slide blacks and whites to their correct printing densities.

With respect,
TJS
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