On Tuesday 08 February 2005 21:00, Roine Gustafsson wrote:
> On Tuesday, Feb 8, 2005, at 17:27 Europe/Stockholm, John Gay wrote:
> > Well, I finally figured out how to get POV-Ray to output non-3:4 ratio
> > frames,
> > so I'm playing around with using Wide screen setting.
> >
> > For extra resolution, I'm generating 16:9 frames at 2048 X 1152 for
> > scaling
> > down. The default output setting is:
> > PNG image data, 2048 x 1152, 8-bit/color RGB, non-interlaced.
> >
> > Which got me thinking about colour depth again.
> >
> > POV-Ray says that png and ppm formats can handle upto 16 bit/color
> > RGB. And
> > the Hollywood standard for movie editing is 32 bit/color RGB.
>
> Where did you get that info?
> The "standard" for a long time has been 10 bit log (Cineon/DPX), which
> is what they scan raw film in for special effects and post processing.
> That will give you 10+ stops, which is better than well exposed negs.
>
> 32 bit per primary would be an enormous overkill.
>
From here: http://cinepaint.sourceforge.net/
<QUOTE>
CinePaint is painting and retouching software primarily used for motion
picture frame-by-frame retouching and dust-busting. It has been used on many
feature films, including THE LAST SAMURAI where it was used to add flying
arrows. CinePaint is different from other painting tools because it supports
deep color depth image formats up to 32-bit per channel deep. For comparison,
GIMP is limited to 8-bit, and Photoshop to 16-bit.
CinePaint Development
The film industry started development in 1998. Motion picture technology
company Silicon Grail (later acquired by Apple) and motion picture studio
Rhythm & Hues led the development, with a goal of creating a deep paint
alternative to the recently discontinued SGI IRIX version of Adobe Photoshop
that would support the emerging Linux platform.
</QUOTE>
> > But I don't see
> > anything in the how-to or man pages/help pages regarding colour depth?
> >
> > Can I use 16bit/color RGB png or ppm images?
>
> No. There has been some talk of extending the Y4M format to >8 bits,
> but today it it 8 bit only.
> If you are just compressing the final result, it shouldn't matter,
> since the output will always be 8 bit because of the DVD standard. More
> bits is only needed if you have a long and complicated workflow.
>
So I need to stay at 8 bits.
> > I'm also thinking about trying 4196 X 2304 frames to scale down to
> > 1024 X 576.
>
> That is actually not the best way. Render in the final resolution and
> let the renderer do the subsampling is always best. It can also be
> very much faster, since the renderer can optimize the subsampling.
>
But the renderer still produces whole pixels, which I can see in the frames
and the mpeg output. even using AA without jitter. I was hoping the scaler
could fix this.
> > Time not being a factor, I prefer max quality, would yuvscaler or
> > y4mscaler be
> > best for this job? I'd like to keep the maximum image quality right
> > upto the
> > mpeg encoding stage.
>
> Don't poopoo the rendering time; you might be looking at days per frame
> at very high resolutions, esp with a raytracer.
>
I know, but I'm creating small sequences for testing. I can always throw more
CPU's at the rendering when the time comes.
> > I still need to work on my modelling, but there are plenty of POV-Ray
> > models
> > on the Internet if you know where to look.
> > Any other comments/suggestions about rendering images for wide screen
> > DVD
> > resolution would be good on this thread.
>
> Remember to think about non 1:1 pixel aspect ratios, and plan for
> interlacing. Also remember some RGB colors are invalid Y'CbCr so
> preview your test renderings in Y'CbCr before the final render.
>
I know. POV-Ray creates 1:1 pixels. the scaler should convert these to the
proper aspect for wide screen. POV-Ray can also generate interlaced frames.
As for invalid RGB values, I don't know how to stop POV-Ray from generating
such values, so I just need to let the mjpeg-tools take care of that.
Thanks for the comments.
John Gay
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