Mailing List AE-List@media-motion.tv ? Message #43785
From: Py Fave <pyfave@gmail.com>
Subject: Re: thx for responding to gradient question
Date: Tue, 22 May 2012 10:47:37 +0200
To: Sixtus Beckmesser <sbeckmesser@gmail.com>, After Effects Mail List <AE-List@media-motion.tv>
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lets keep this on the list. i am curious of other people's responses

as i see it ,the problem is in the media.
if you can't display more than 8 bit colors  ,
you're stuck.

professional systems use SDI connexions on expensive monitors mostly to get these things  solved.
i don't know exactly in video , but in (digital) cinema , you can keep your image 16 bits on screen .
(dpx or tiff support this, f. i.)


anyway , if it is for color calibration, don't consider that the probe will be aligned on a pixel .
it will give a median value from surrounding pixels , this will smooth out your values .

and if you use the "noise" trick (in fact it is called stochastic distribution or something like this :-)
it will give pretty good values.

if you HAVE to output bluray , it will be 8 bits.

16 bits is not affordable  for consumer market  now .
tell me if i'm wrong please .

"I'd be eternally grateful." hehe
have a nice day


Thanks for responding to my query about gradients. You're the first one to do so.

The MPEG-4 encoders for all Blu-ray require 8-bit video in YUV form, which is one of the primary faults of the system. Using ten bit RGB as input to an 8-bit YUV format won't help matters if the results are still rounded off to 8 bits with the same round-off errors as with 8-bit originals.

I realize adding noise will smooth gradients, but these are test patterns where I need the Blu-ray players to produce the PRECISE values I intend so as to test the gradient response of the SCREENS! 

Attached is the file I've been trying to encode without success. Note on the horizontal axis every pixel value between 16 and 235 appears for precisely the same amount of time (except for some stuff going on near the left edge). With every encoding procedure I've tried, either some pixel values are repeated or are repeated, with consequent increased banding on playback.

Thx again for your attention and if you can figure out how to do this I'd be eternally grateful.

David

 
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