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@tida, it is almost what you said. But precision here is the percent change in Brightness per digital step.

In my first message here I was talking about : 1/L(profile, Point). I dint take any gamma function saying Luminance was given in a linear mode,hmmm :-)

For instance take the profile :Gamma2.2 in 8 bits : choose brightness of 2%. Lets calculate x on a scale of 256 that gives that brightness of 2%:

(x/256)^2.2 =0.02 => x=256*(0.02)^(1/2.2)=43

What is the difference (delta) of Luminance between 43/256 and 44/256 (1 digital step)?

delta=(44/256)^2.2 -(43/256)^2.2

and percent change is: delta/(43/256)^2.2= (44/43)^2.2 – 1=0.052=5%

You can read it in the graph given by VK : 2% brightness gives 5% in the red 8 bit curve.

Isn't the discussion about simple mathematical problem of loosing information either if you round up/round off or using absolute values and you are allowed to do that in a certain digit region.

For example you want to multiply and come back to same value by division. It's only allowed to calculate with one digit precision.

round (value,digits)

round(0.4 * 0.4, 1) = 0.2

round(0.2/0.4, 1) = 0.5 (not 0.4 any more)

Abs(value,digits)

Abs (1.5*1.5, 1) = 2.2

Abs(2.2/1.5, 1) = 1.4 (not 1.5 any more)

If you do not want to loose information you have to calculate with 2 digits precision but only display one digit.

About 8-bit

http://www.displaymate.com/ShootOut_Part_3.htm

@ shian

forgot to add: do you ever use adobe link for moving between AE and premier pro? or do you always use xml/aaf/edl?

I haven't ever used Media Encoder. It appears to be Adobe's answer to Compressor which I love for encoding M2v's. Compressor is the only option I know of right now that has given me consistent results in the arean of flawless playback on any player.

never export twice - use XML/AAF/EDL to transfer your edit into another program. It's lossless. You are simply moving your EDL (Edit Decision List) with the same raw footage you were editing in your NLE into your grading program. All your raw footage comes in and is "magically" edited the way you did in FCP (Premiere, Vegas, or whatever you are using.) If that doesn't explain it, I don't know what will.

If you export 4:2:2 8bit you will get banding. Use a 444 codec - ProRes or DNxHD

For vimeo I use Mp4, 2 pass, 18,000 kb/s

For compressor going to Bluray use a CBR somewhere between 14,000 - 18,000. you'll have to do some tests to see which gives less errors during playback. I have settled on 14,000 myself. but I wish I had @driftwood's knowledge of I B and P frames so I could tweak that aspect as well.

For those working in AE or on pc in general (and unable to encode prores), there's an excellent codec for uncompressed file. It's called "lagarith lossless codec" and it's the most efficient codec I used (but you'll end up with HUGE files). This codec is for .avi format. First time I used it was for a job for a famous luxury swiss watch maker, and none of the codec or uncompressed format could do the work any justice in its fine details while displayed on bluray. Then I used Lagarith and now I use it for every important project.

My 2 cents here :-)

Actuallty what is a color profile for our loved GHx? It is here a signal mapping from 16 bits (direct from sensor) to a signal of 8 bits (recorded).

Imagine first setting named: F (flat) and a different one: NSF (not so flat).

Imagine same image recorded in F and NSF. In this image you will get one physical point named E here (of the source signal) having same value in F and NSF. Lets say for instance value of E= 43. The value of E (here 43) reffers to same source luminance in the actual image.

0 means full black 256 means full white.

Profile F is flatter than NSF that means that you give in profile F more bits of information for any points whose value < E compared to same points in profile NSF.

Considering a point P(x,y) of the initial image, lets say : L(F,P(x,y)) the luminance of P(x,y) in profile F, L(NSF,P(x,y)) the luminance of P(x,y) in profile NSF.

So we have : L(F,E)=L(NSF,E)=43.

We have 2 cases:

cases 1: For every P / L(F,P)< L(F,E) we have : L(F,P)>L(NSF,P) so that 1/L(F,P) < 1/L(NSF,P) That means for shadows, profile F is better in term of precision : 1/L(F,P) is the relative precision of signal (while mapping or for any work in PP) in profile F for the point P.

cases 2: For every P / L(F,P)>L(F,E) we have : L(F,P)<L(NSF,P) so that 1/L(F,P) > 1/L(NSF,P). Here we are in highlights and profile F is worse (less precise) than profile NSF. If we were in a 10 bits signal, precision should be 4 times better (smaller) and it will be ok in term of quality. I think this is the point stressed by @FilmingArt.

But, yes there is a but, here in case2 L(F,P)>L(F,E) that means we have in highlights a lot of bits of information and precision 1/L(F,P) is quite small (that means quite good) even if greater than 1/L(NSF,P) so that argumentation of @FilmingArt is not so relevant as far as my analysis is ok.

Again my 2 cents here :-)

@shian I'm just getting in to the grading and post universe and reading your posts and threads makes my head explode on a daily basis but I love it! I feel like every time I read a long discussion about an area I want to stop you and say,"Ok, I heard you tell me to turn the computer on, then you lost me. Can you start from there." LMAO! Thanks for all you dedication and hard work sir.

@Peter123456 you want the cleanest image possible before going to bluray. I've done encodes from both 444 and 422 masters exported from AE with the same settings just to see, and the 444 held up better every time. But I encode in compressor. I've tried letting AE do the compression - no good. I've tried letting toast do it - no good. I spent a week tweaking my settings, and I get the best results from 444 ProRes to Bluray. Even when letting a pro house do the encoding. They love me for walking in with a hard rive and all my assets lined up, and a ProRes444 master.

Sam's point is valid too. Just make sure if you are going to broadcast that you conform everything back to broadcast standards at the end, or it'll get rejected. But this is broadcast video 101, you guys already know this stuff, right? Cuz you've been dubbing digibeta masters from day one.

@shian, If my only distribution method is bluray (and I will not make any further changes to the footage in the future), do you still recommend rendering to a 444 high bitrate codec before burning to bluray (as indicated in steps 10/11 of your workflow)? The Bluray max bitrate is 54Mbps, so can't I just render to MPEG 2 around 54Mbps? Thanks for your time.

benefit? control and flexibility in post