"Kenneth" <kdw### [at] earthlinknet> wrote:

> So...if I had chosen 2.2 as my overall system gamma (rather than 2.0), then
> I would have had to alter each of  my "linear" grey-band values by raising
> them to the power of 2.2, rather than just squaring them...to get the same
> pleasing visual result.  Correct?

Yep.  When you start messing with gamma, particularly investigating the GAMA
chunks in PNGs, the number 0.45455 comes up a lot because it is 1/2.2.  POV
essentially raises every pixel value to the power of 0.45455 before writing
it to disk and placing it it in the preview.

To test all this I produced a scene of four coloured boxes and rendered it
into a 2x2 PPM.  That is human-readable, so I didn't need to load it into
an editor to run a colour picker over it, risking another application
applying gamma to the values.

You can go around raising things to the power of other things but when it
comes down to it, I think accepted POV practice is to munge numbers until
it looks right.

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