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clipka <ano### [at] anonymous org> wrote:
> Warp schrieb:
> > clipka <ano### [at] anonymousorg> wrote:
> >> In 3.6, however, the rgb 0.5 object (B) will look way darker: POV-Ray
> >> will have output "127"
> >
> > You mean that POV-Ray 3.6 didn't gamma-correct the output at all, while
> > POV-Ray 3.7 now does?
> I mean that 3.6 didn't do it /by default/ (which is what you've been
> asking about all the time).
> > Does that mean there's now a new option to set the gamma correction of
> > the created image (the actual pixels, not just some header data in the
> > image file format)? Is there a way to turn this off, if one so desires
> > (eg. if you really *want* the pixels to be exactly (127,127,127) and
> > nothing else)?
> Yup. "File_Gamma" is the magic ini file option. Set it to 1.0 and you'll
> get linear pixel values, plus (for PNG and HDR) a header saying that the
> data is linear. Set it to 2.2 and you'll get gamma pre-corrected pixel
> values, plus a header saying that the data is pre-corrected for a gamma
> of 2.2. (The latter is highly recommended though, as not all viewers -
> browsers included - support linear image data.)
> Note that this makes it impossible to deliberately mess with gamma for
> artistic effect in POV-Ray when you use PNG output and all your image
> processing software handles gAMA chunks properly: You can only affect
> the encoding of pixels - and thereby the dynamic ranges of highlights
> vs. shadows - but not their interpretation.
> At least that's the theory as known to me. I never tested in detail
> whether it indeed works exactly as intended.
Well, this clears things up a bit. I'm still not 100% happy that old
scenes will render differently by default, but I suppose it's an acceptable
change.
I highly recommend writing a concise and clear explanation of this in the
"what's new in POV-Ray 3.7" section when the final version is published.
Else it's only going to cause a lot of confusion.
--
- Warp
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