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-   -   Color Correction (http://www.dvinfo.net/forum/techniques-independent-production/33049-color-correction.html)

Jim Exton October 6th, 2004 09:30 AM

Color Correction
I don't know how to phrase this question and make sense and not look stupid at the same time.

I understand bigger format = better picture quality.

I understand faster computer = less rendering time.

What I don't understand is color correction programs. Is there a difference between what a professional post house would use and After Effects? If so, why?

If I spit DV into a computer, I am thinking that it doesn't make a difference at that point what program is used because DV is still DV. I am wrong?

I am new to color correction, this is why I am asking. I want to know if someone shoots a feature on DV and uses their home computer to color correct/audio mix, etc and then blow up to film, are they not going to get the same results as upconverting it/or using a Symphony, etc. And if so why? What makes one program "better" or more powerful than another?

This question is just for color correction only, not 3d effects or animation.

Andre De Clercq October 6th, 2004 10:18 AM

There are a couple of elements involved...DV is indeed DV, but when it comes to "manipulate" the low res chroma part in the DV (4:1:1) signal there are some more elements involved too. As you know, before processing DV data in a computer, the first thing to do is to decompress the data into its components where the DV codec allready plays a role. Furtheron most low-end NLE's just process in RGB (simple algorithms) which is not the best solution for color issues...YUV level processing used by more advanced systems is better. Finally the chroma components (UV) can be uptransformed (spatially and grayscale wise) before manipulation (4:2:2....10bit,..) and downconverted before recompression (codec quality again) into the DV format. This up/down conversion reduces rounding errors in digital calculations.

Charles Papert October 6th, 2004 10:32 AM

Post houses use dedicated "boxes" such as the DaVinci to perform color correction, rather than software-based solutions. As such, the range of capabilities and sophistication is greater and the results are immediate, no rendering involved. For instance, to isolate a section of a frame with software, one has to build a matte point-by-point; the DaVinci uses "power windows" which can be sized and manipulated via trackball.

Joshua Starnes October 6th, 2004 10:46 AM

And, of course, the professional post house is going to have professional, full-time employees who do this sort of thing day-in, day-out, all day long, know the technical tricks and problems of color correction (or sound, or whatever) and can get a lot out of their boxes very quickly. So your paying for their expertise as well, and I've found that is worth more than all the software in the world.

Rob Lohman October 6th, 2004 03:38 PM

It boils down to the following (as others have touched)

1. computing power

2. efficiency / quality of the algorithms

3. tools available

This is all drive by money and time (which is money).

It's like why is one car more expensive or "better" than the other.
Can you drive with all of them? Yes.

However one car is much faster than the other. Another car might
steer much more precise or have a folding roof for example.

So yes, we can do color correction as well, but we don't have the
sophisticated tools they do. Their tools are more, usually better,
faster and definitely much more expensive.

A lot of features will trickle down into consumer grade programs
as hardware speeds increases, prices drop and the professional
stuff moves on to new things (3D look-up-tables are the big thing
now it seems).

Also keep in mind that they usually work a lot more with the tools,
so more gets added (also by customisers) and more is needed.

The motion picture business needs to keep improving these things
to get the better effects and faster turnaround times. There is a
lot of money involved versus the con-/prosumer business.

Jim Exton October 6th, 2004 07:32 PM

Charles -The people at the post houses are expert color correctors, but you have to start somewhere. I figured by doing it myself, I would at least be able to communicate with them better should I reach that level. I by no means expect to achieve their level at all, I just figured if one went straight to DVD, cable, foreign video, etc; would After Effects be could enough if the person doing the color correcting knew what they were doing?

I guess I was just unsure how a major distributor would want a film to be delivered. I didn't know if the master DV tape looked good, having been color corrected, that they would take it or if they would insist on having the DV tapes "blown up" and re-done at a higher format.

Rob Lohman October 7th, 2004 02:29 AM

If you seriously want to get into color correction work for feature
films it probably best to save for some of the higher end packages
like Digital Fusion or Combustion to start out with. Those packages
have a lot of the same tools that even higher end package use
like smoke/inferno and davinci.

But in the end you can do almost anything they do, only with a
lot more work. Power windows can be emulated with masks or
cookie cutters or paint programs like photoshop. If you can make
an alpha channel matte with feathered edges and such you
basically have a static power window to apply color correction
effects to. We have a lot of power full tools these days, it only
requires (a lot) more work to bring it all together like the big boys.

Don't forget that even they sometimes have layer upon layer of
effects and can work for weeks on a shot. We tend to rush over
things like that which doesn't help either.

Another thing we don't have yet are powerfull trackers. The
cheapest one is SynthEyes and if you don't have such things
you will need to do it manually taking a lot more time for example.

Jim Exton October 7th, 2004 08:45 AM

I have a better understanding now of how the big boys do it, I didn't realize you had to be able to track and make mattes for color correction, it is just more sophisticated than I thought.

Thanks to all of you for replying.

Rob Lohman October 7th, 2004 10:08 AM

That's done a lot. For example to change the exposure of someone's
face (perhaps to better match it to some other changes in the
scene). Or to brighten snow but nothing else for example.
Or to change the contrast just in the dark areas. Or to change
just the sky in color or whatever. You get the idea!

I've seen them do lots and lots of sometimes small detailed stuff.

Dragi Vujacic October 14th, 2004 02:52 AM

Start with something
Try this - Colour correction for digital video by Hullfish and Fowler or something similar. At first you have to start with understanding a process of correction- why is something put on this way or that, and than you'll need a lot of practise and practise. Try After Effects or Combustion. They have amazing tools and Light-Colour meters. If you know how to do, with them you can do everything like Da Vinci. Da Vinci is great and used a lot in film postprocesing. Donít be afraid. For example Combustion has the very same colour correction engine like Smoke or Discreet - High-end solutions used in corecting for bunch of movies. After Effects are also used all the time in Hollywood for movies like Star Wars and in a lot of worlds high budget adverts. Donít be fooled. If you fill like - you will love it - then just try.

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