subpixel mapping & / or clamp

[mayanic]

Hello,
for sure this one is a wide discussed topic - so sorry for bringing it up again ^^

I read this (vlado 2009): "If "sub-pixel mapping" is on, first the sub-pixel values will be clamped, and then they will be averaged together. So your final result will be (0.5+1.0)/2=0.75 (light grey)."

and later: "Yes, you still have all the [32bit color informaion stored in the hdr-image] range available (unless you specifically also enabled the "Clamp output" option)."


But this makes me think. Does sub-pixel mapping clamp the values first?

hope to hear from you soon
br mayanic

[tashko.zashev]

Hi,

Does sub-pixel mapping clamp the values first?

The Subpixel color mapping option simply force V-Ray to apply any clamping (in case that Clamp is enabled) and color mapping on a sub-pixel level meaning on the samples inside the pixel, instead of the final pixel color. In some occasions this lead to a slightly different results in the bright areas even if the clamping is not enabled.
So yes, there some color clamping with this option ON, since the final pixel color is decreased.