[CinePaint] Really basic script for batch converting.

Guys

Thank you all for your replies to my query.

Bob, I had looked at Tiff 32bit unfortunatly the compositing/NLE app I
intend using does not support 32bit, which is a shame as Tiff
I believe via Cinepaint for sure can have an ICC profile embedded.

Frank, thank you for the link to Netpbm I shall give it a try and in
response to clarifying my need, it is basically this:

The goal is to composite live action video and 3D sources together in a
32bit float linear environment. The compositing is not a problem it's the
process of maintaining maximum quality of the source material, ie:minimum
degradation getting that 8 bit mpeg2 (YV12) HDV sources into the 32bit
float RGB environment.

The compositing and NLE software I intend using the video footage in (as
image sequences rather than video inside various codecs) at some point
converts from the YV12 to RGB and I have a few concerns as to the way it
handles that from a quality and tonal range point of view.

I would prefer to control the conversion seperately and present best
quality I can muster into the app.

Currently I am using AVISynth to convert YV12 4:2:0 mpeg2 video to RGB
image sequences, full range 0-255 no remapping, no clipping super
whites/sub blacks. I want whatever my camera catches transferred to the
NLE and deal with it there.

I take care to expose as best i can using the Ansel Adams zoning theory in
my evaluation of a scene + zebra patten, no sharpening in camera, no
contrast boosting or any of those other things employed to make video look
pretty straight out of the camera. What I'm doing is to capture as much
tonal range as I can. Well as much as you can in a compromised gamma 2.2 8
bit heavily compressed format, but I simply can't afford more expensive
cameras like a RED. :-)

I'm exporting as 8 bit .png's, thousands of them. :-) I could drop them
into a .mov or .avi container to improve managability.

So my aim is to get the best transfer from YV12 to RGB as I can first of
all. The AVISynth route is giving me the most amount of unique colours
within the resultant .pngs. No gaps in the histogram in 8bit.

As soon as any contrast/brightness/levels is done in 8bit more data get
thrown away, gaps appear in the histogram no smooth undulations.

I've read that when these 8bit images are taken into Adobe After Effects,
no doubt Photoshop as well and a 16bit or better project workspace is
adopted it is said that, "something miraculous happens, the gaps (to the
histogram) have disappeared, what's happened is the old colour values have
been freed from the 8bit restriction and moved freely into the new range
(16bit) evenly distributing themselves"

Is Adobe After Effects interpolating values to fill the gaps, I'm under no
illusion that this means true native 16bit, it doesn't there were only 256
levels to start with but does this 'interpolation' mean that further image
manipulation does not have such a aggressive effect on the tonal values
within the image, if now interpolated values exist to smooth the whole
thing, depends on heavy handedness I guess.

So that's where I'm at, trying to massage my 8 bit video files into a
32bit precison environment for compositing and colour correction.

But having to do this on thousands of images really requires a command
line approach I think. :-)

Sorry for a very long post. :-)





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