[opendtv] Re: RGB mania
- From: Doug McDonald <mcdonald@xxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sun, 16 Jan 2005 09:17:18 -0600
Craig Birkmaier wrote:
> At 8:46 AM -0600 1/15/05, Doug McDonald wrote:
>>
>>I have never ever seen a movie with detail in the blacks.
>
>
> How sad...
>
> There are many classics that take full advantage f the ability to
> push blacks when there are details there that the cinematographer and
> director want you to see. Horror and murder flicks are a good
> example; the director MAY want you to see the perp creeping through
> the shadows to get the full dramatic impact. Then again, they may
> want you to be completely surprised, in which case they will tend to
> suppress the details in the blacks.
>
> What is important to this discussion is that they have the ability to
> do this in post.
>
What you call blacks I call "Zones 3 and 4" :-) :-)
By "blacks" I mean "Zone I".
> Likewise, you need lot's of headroom in the whites and specular
> highlights in order to deal with scenes with very high contrast. One
> of the biggest weaknesses of HDTV cameras is that they cannot handle
> scenes with extreme contrast.
They could if designed right. The solid state sensors used
are vastly and absolutely in every way superior to film,
except raw pixel count. They have enormous dynamic range,
usually in the 16 bit range, 60000:1, if there is
enough light (outdoors, for example). You are not going to
get full use of that of course without getting all the bits
out of the camera and into storage somewhere, or at least
close (e.g. store the 0.8 or 0.9 power of the data.)
>
> Everyone should have a copy of Joe Kane's Video Essentials, so that
> they can learn how to properly calibrate their displays to maximize
> the perception of the full dynamic range.
That disk is the single worst cause of lost detail in home
video. It sets the black level too low, resulting in
mush lost detail in the blacks.
>
>>Do you in fact, if you use a gray card or incident light
>>meter for setting film exposure, correctly rate the film speed
>>to get details in the blacks? That is, set the ASA rating
>>an absolute minimum of 2/3 stop slower than the manufacturers
>>ratings and more typically 1 or 1 1/3 stop slower? IF using
>>a spot meter, do you set the exposure so that the absolute
>>darkest part of the scene is well up on the toe?
>
>
> That is the decision of the DOP/Cinematographer, based on the look
> that the director is trying to achieve. I cannot imagine why you
> would set the blackest black well up on the toe - this would waste
> much of the dynamic range that the negative is capable of capturing.
You set the blackest black well up on the toe if
you want details in the blacks. If you don't, by definition
you lose detail in the blacks! I'm not saying you have to set
it up above the toe into the linear gamma region, of course.
But if you want detail in the blacks (Zone 1) you MUST get them
well up onto the toe. As I said, I have never seen a movie with
detail in Zone 1. Stills, in photo art galleries, yes, they are
a "dime a dozen". Movies, no.
Doug McDonald
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