 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Rune wrote:
>
> Could you refresh my memory in what exact order things are handled now?
> First antialiasing, then gamma-correction, then color clipping? Where does
> the non-linear tone mapping fit in? Is it the same as gamma correction?
The term 'tone mapping' is used for the combination of all operations
used to map the light intensities returned by the raytracer to the color
values of the images. In the simplest case this is no operation at all
but in most cases you will use at least clipping and gamma correction.
More sophisticated techniques exist which usually make the clipping
completely unnecessary because the mapping function maps the infinite
range of possible intensities to a finite interval.
POV-Ray 3.6.1 does antialiasing with the unmodified intensity values,
clips them, gamma corrects them and then writes them to the file. In
MegaPOV (1.0 and later) the film exposure is (when enabled) applied
before the clipping and in fact makes it unnecessary (it is still there
but has no effect).
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 06 Jul. 2004 _____./\/^>_*_<^\/\.______
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Slime wrote:
>[...]
>
> I think, however, that there is one thing everyone can agree on: the primary
> purpose of antialiasing has always been to remove jagged edges. POV-Ray
> 3.6's antialiasing does not always do that anymore.
The effect you get with antialiasing in POV-Ray 3.6.1 is like rendering
in high resolution to a HDR image and scaling it down.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 06 Jul. 2004 _____./\/^>_*_<^\/\.______
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Christoph Hormann wrote:
> POV-Ray 3.6.1 does antialiasing with the unmodified intensity values,
> clips them, gamma corrects them and then writes them to the file.
And what exactly was wrong about clipping before antialiasing, as long as
gamma correction is applied after antialiasing?
Better yet, reply to Slime's post, since it deals with details I haven't
written down here.
Rune
--
3D images and anims, include files, tutorials and more:
rune|vision: http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
I think I agree with Thorsten and Christoph that 3.6 behaviour is
mathematically correct and that 3.5 had a bug/feature.
I think I was a feature as it allowed us to create scenes that
looked like we wanted, eventhough it was based on faulty code.
I don't agree with Thorsten that everbody now has to change
their scenes and that from now on it is de facto forbidden to
use bright objects. Or that at least we are not allowed to
complain if that results in jagged edges.
I do agree with Christoph that some solution has to be found to
counter this unwanted phenomenon. I find his response more
constructive than Thorston's.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Christoph Hormann wrote:
> The effect you get with antialiasing in POV-Ray 3.6.1 is like
> rendering in high resolution to a HDR image and scaling it down.
So do that when the user has selected HDR image as output, but not when the
user has selected one of the common "old" formats limited to the 0-1 range.
I'd like to hear your thoughts on Slime's other posts
(the one posted Fri, 27 Aug 2004 16:19:34 -0400).
Rune
--
3D images and anims, include files, tutorials and more:
rune|vision: http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Slime wrote:
> [...]
>
> Gamma correction should always be done as the last thing in a renderer's
> output. In fact, if the user plans to do anything more with the output
> image, then they should turn off gamma correction, do whatever
> postprocessing they want, and *then* apply gamma correction. Then, when the
> image is displayed on a monitor, the gamma effects will cancel out the gamma
> correction and present the viewer with the correct image.
That's right if you use gamma correction purely for the purpose it is
intended for (i.e. for compensating the monitor gamma). A lot of people
however use it for artistic purposes just like the clipping. It is
still fairly common for example to design scenes to show up correctly on
a certain monitor without gamma correction.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 06 Jul. 2004 _____./\/^>_*_<^\/\.______
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
andrel wrote:
> I do agree with Christoph that some solution has to be found to
> counter this unwanted phenomenon. I find his response more
> constructive than Thorston's.
Hehe, agreed, but that's hardly news...
Rune
--
3D images and anims, include files, tutorials and more:
rune|vision: http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Christoph Hormann wrote:
> That's right if you use gamma correction purely for the purpose it is
> intended for (i.e. for compensating the monitor gamma). A lot of
> people however use it for artistic purposes just like the clipping.
But that's not what it is intended for! This is not the sole reason we are
facing the jagged edge problem now, is it? If *anything* is an "artistic
trick" then using gamma correction for the purpose you describe would surely
be it!
Slime made a good and well-worded suggestion on how the process could work,
and your only reply is to point out that it would break scenes where gamma
correction is used incorrectly (or as an artistic trick at least)?
This goes completely against your own argument in other posts... I don't get
it.
Rune
--
3D images and anims, include files, tutorials and more:
rune|vision: http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Rune wrote:
>
>>POV-Ray 3.6.1 does antialiasing with the unmodified intensity values,
>>clips them, gamma corrects them and then writes them to the file.
>
> And what exactly was wrong about clipping before antialiasing, as long as
> gamma correction is applied after antialiasing?
I explained the quite in depth in my previous replies. If anything is
unclear about what i wrote please ask. If not you will find the
explanations there.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 06 Jul. 2004 _____./\/^>_*_<^\/\.______
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> The effect you get with antialiasing in POV-Ray 3.6.1 is like rendering
> in high resolution to a HDR image and scaling it down.
Which is great when you're rendering an HDR image, and really ugly/useless
when you're rendering in a format with a range from 0 to 1. The range that
values are clipped to should be the same as the range that the output format
actually supports.
- Slime
[ http://www.slimeland.com/ ]
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
