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Re: Custom Curves

> the range is so limited on DV custom curves

Help me out here, I don't understand what you mean by limited range.  You
can take the custom curves controls and turn things upside-down and
backwards if you want.  Can you give me an example?

> the funny thing is that when you make a print of a print . . .the curve
stays in the same
> shape

Right, because for a given step change in exposure the response of the
second print is exactly the same.  The fact that you are exposing it with
something that is "pre-curved" would give you the increase or distortion in
No problem, we can fix it in Post!   :-)

> the limit is when it gets so contrast  that you just have black and white,
no more mid
> tones, then your curve looks like a step of a staircase.

Well, OK, the response curve never changes.  It is what it is for a given
type of stock.  I think what you are saying is that the compounding of
nonlinearlities or contrast distortions ends up looking like step changes as
opposed to smooth transitions.

> Why ... manufacturers have not implemented years ago such a gamma
> control ...?  It is so much better than black and white level

Are you talking about a gamma control that increases contrast nonlinearly in
blacks and whites while leaving everything else alone?
If that's what you want custom curves will do it.  In fact you can apply
this kind of a response selectively and in different proportion to any one
of the four channels controllable by this function:  Y, R, G, B.  So, for
example, you could increase black and white level contrast (to the point of
solarization if you wish) to just the Red channel and leave everything else
alone.  I'm not sure why you'd do this...but you can.

>you get rid of noise in whites and grain in blacks, really cool,

Yeah, with the right material this can work amazingly well.

>However very often you need to see more details mostly in blacks
>that's why a black stretch is useful, the regular gamma does it perfectly

That's where I see the power of the 2K color corrector coming in.  You could
apply a "conventional" gamma control before or after your customized control
just because the box has layers that can be "prioritized".  (Keep in mind
that I might not be using the correct "daVinci approved" terminology here)

> Martin are you a colorist or an engineer or a mixture of both ?

This is now an interesting question.  I'm a Telecine engineer currently
working at Hollywood Digital in Los Angeles.  I am also working towards
transitioning into Coloring.  One of the main driving forces behind this is
my interest in all of the new technologies around the corner:  ATV/DTV/HiDef
and Film resolution work.  I think amazing things are going to start
happening in the Telecine environment in the next few years.  I see a whole
range of work that we've never done electronically migrating towards TK.  I
also see a time when Colorists are going to have to sharpen technical
skills, acquire new ones and have a deeper understanding of an even wider
range of technologies than what they now have to deal with.  I decided it's
about time I get my hands dirty and start enjoying that creative outlet you
guys have so much fun with!

I am also trying to imagine what Bob Festa's postings are going to be like
when he can start charging the equivalent of $2000 to $3000 an hour because
of doing absolutely insanely complex --but very much fun and creative-- work
in a film-to-film environment.


Thanks to Casablanca Finish (Sao Paulo) for support in 1998..
No product marketing allowed on the main TIG.  Contact rob at alegria.com
950 subscribers in 36 countries on Fri Mar 13 08:05:48 PST 1998 
complete information on the TIG website http://www.alegria.com/tig3/