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View Full Version : Color Correction, LUMA : Pro expertise ?


Gpin
10-28-2002, 06:43 PM
PS : there is a similar post inside the AE forum, I post it here as well, because my question are not related to a specific package. Thx for you understanding


Hi,
I'm looking for some expertise in color correction in any compositing package. I personally use after effects and I'm well aware of it's limitation (though I use some plugins for the CC).
My question applies to any system.

My question is somewhat simple.
We just finished editing an HD (1920x1080 24p) commercial, and I did some major color correction (vfx) to the footage

the example : shot in North Amercia with a very bad weather, I had to turn the scene into a Jamaican beach. So, I applied a major color correction to the water, faked the transluscence of the sea bed, change sky, add caustic and so on......

But now, it's time for the output. And I have a lack of experience regarding final outputs, specially regarding the luma value.

When the footage was shot, everything ran through a HD vectorscope to make sure the levels were all good. But the raw footage I've been working on is very uncontrasted, I don't think it's a bad thing, it's to my understanding meant to keep as much data in the frame. (I was on set talking to the DOP about it)

But the final look I'm looking for needs to be more contrasted, and I want make some final color adjustments to the whole thing.

I'm very hestitant about applying those changes, because as soon as I adjust levels, contrast, brightness, gamma,.... I'm somehwat losing visual data.

FOR EXAMPLE : Imagine having a guy with a black shirt, and in the raw footage you can clearly see all the wrinkles, but when increasing the contrast, I lose the wrinkles details into a black area. Bare in mind, that I'm not pushing to the extreme were I lose everything ! I have a clear understanding of photography.

My question is more about "WHAT IS ACCEPTABLE ?".
Because when I run the footage through a vectorscope, or an RGB histogram, I can clearly see that I'm pushing the blacks and whites quiet far......

Or should I just ignore the level infos, and follow my visual eye and act more as an artist.

I'M REALLY LOOKING FOR SOME PROFESSIONAL EXPERTISE AND ADVICES ON HOW TO ADJUST THE PICTURE RESPECTING TECHNICAL RULES AND MEETING THE ARTISTIC REQUIEREMENTS.

So all the Shake, DaVinci, Inferno artists......please help.

Thanks in advance


__________________
Gpin.

fred
10-29-2002, 04:00 PM
i guess the most important thing is whatīs going to be the final product? are you going to transfer it to film or are you going to do a downsize and output on video (ntsc or pal?)? and what equipment are you working on, do you have a proofed display and a waveform monitor?
i guess those two points are very essential if you want any sort of advice. please let us know!

Gpin
10-29-2002, 06:49 PM
Yes we do have an editing suite with vectorscope and proper NTSC monitors.
And the finla output will be NTSC, though we have to deliver a MASTER HD (we will do that through another post facilty).


My question isn't too much about the technical apsect.
It's more to understand the approach (process) when doing color correction.

Look at commercial > some are blue tinted, some saturated, some very dark, some very "dreamy"......

So how to get those effects in an artistic way while keeping a balance between the look and the technical rules.

Thx in advance.

fred
10-30-2002, 03:10 PM
well, i guess itīs a bit hard to give artistic advice as i donīt know the film youīre working one AND iīm not the one responsible for grading it.
but the process you normally do is to create a "look" using several exemplaric shots until youīre happy with it and then try to apply it to all other shots in the sequence. if youīre absolutely free in choice there are a thousand ways of doing this so i guess you just have to follow your eye.
on the technical side it would be helpful that you try to match the contrast and luminance values for each shot (use the waveform for this in the first pass, the results you get are pretty good most of the time and only need a little tweaking). With colors itīs a bit harder as you canīt really define them over the vectorscope. Just do what your eye tells you and try to match the overall tone of shadows, mids and highlights. Be aware of the surrounding where the film is going to be shown (is it a dark cinema or ist it tv? - the shadows will appear completely different). Be very careful with selective color correction, 8 bits will ruin everything very fast. The only tool i know that can do a proper selective color correction on video is flameīs/infernoīs color warper.
and - this may sound dumb but iīve seen lots of people doing this - never ever color correct a clip twice (you lose lots of information, especially working in 8bit colorspace) and never ever throw away your source material (you will do about 5 passes until the grading is final).
i hope this was of a little help for you, if youīve got more questions just ask!

Gpin
10-30-2002, 04:26 PM
So, applying color correctin on an already color correction footage isn't a good idea. Good to know !
Didn't know than selective color correction only wokr properly on advanced compositing package. But I did realize than AE is doing a very bad job on selective color correction and I never was able to get the way I want. I usually end-up using mask and mattes to select the area I want to affect.

But what are usually the tools used for color correction.
I believe color balance on low-mid-high are usually a very common tools. I've see some people using using Pedestal, gamma and gain, is that an appropriate tools ?

Unfortunatly AE isn't a real-time playback when using HD footage (though I'm running 2ghz dual Xeon) ....and I don't have a HD editing card, so that's another reason too !!
So, when it comes to compare color corrected shots....it's very difficult to get a sense of the overall. It's very frustrating.

I tried running the same footage on Shake (just testing), and the results are much better regarding CC and playback. But I really have to stick with AE.

So, any other comments, would be appreciate.

fred
10-30-2002, 10:24 PM
itīs still beta for shake, ae and combustion but you should definitely check out colorstar from colorfront (www.colorfront.com - the guys behing 5dīs colossus). i used it as as a smoke* spark and this plugin definitely satisfies all grading needs you could ever have (at least on a desktop system). hope it will be out soon.

for playback problems i think itīs no problem to stick to ntsc resolution, it will be good enough to judge the grading!
if itīs possible in any way you should really switch to combustion for color correction. aeīs tools are really very very weak whereas combustion has one simple & really good module (almost the same as in inferno). check out the CC tutorials thread in this forum for more info on its capabilities!

Gpin
10-31-2002, 05:26 PM
Unfortunatly, I can't seems to find a AE of Combustion beta version on their site.
Do you know if there is available beta versions somewhere ?

Thanks again.

fred
10-31-2002, 10:20 PM
i guess the only way to get one would be emailing them and telling them about your project, maybe theyīll send you a copy?

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