[Tig] instinctive contrast

[S. T. Nottingham III]

I believe the description (by others below) is exactly what I have been
saying:

Chromatic values consist of three components: Saturation, Hue, and
Luminance. All three interact to make up a color stock's contrast, with
colors like Red and Yellow normally having high luminance values, and others
such as Blue and Cyan normally having much lower luminance contents. This
can be seen when RGB outputs from Telecine are viewed separately on a black
and white monitor. The Blue record normally has the lowest contrast, and the
Red record has the highest. Green is considered "normal" which is why the
original Rank Encoders derived luminance from the Green channel. This
phenomena can be see in the Lab as well as in various TV systems - it is the
nature of color as it occurs in the environment. Of course, there are always
exceptions. Blue can have a high luminance content in night-club scenes with
strong color lighting, but the in the normal scene, the Blue record has
fairly low gamma.

Tom Nottingham

 -----Original Message-----
From: 	tig-bounces at tig.colorist.org [mailto:tig-bounces at tig.colorist.org]
On Behalf Of Michael Bittle
Sent:	Monday, March 19, 2007 9:59 AM
To:	Telecine Internet Group
Subject:	Re: [Tig] instinctive contrast

Thanks to Cintel International for support in 2007.
http://www.colorist.org/wiki3
====



Perhaps, then, the technical description of contrast is not one of
absolute values (luma ~ x IRE, chroma ~ y IRE) but rather some sort
of relativistic calculation;

contrast = {red with respect to green} transformed by {green with
respect to blue} transformed by {blue with respect to red}

  (I'll leave the real equations to real mathematicians)

Mike


On Mar 19, 2007, at 11:39 AM, Rob Lingelbach wrote:

>
> On Mar 19, 2007, at 11:55 AM, Michael Bittle wrote:
>
>>
>> Could it be that what we perceive as contrast is not purely
>> function of black and white?
>
> yes, I think you're beginning to describe what I was at a loss to
> explain, that color adds
> something that makes up for a lack of contrast, like your example
> that a 200Hz emphasis will
> improve the perception of bass.  Description of this by example may
> be our only recourse,
> as the technical/scientific explanation is elusive.
>
> Joe Owens wrote:
>
> > It is disturbing how casually most black-and-white from colour is
> achieved by simply
> > turning down the saturation dial.
>
> and this depends on what you mean by disturbing, but I agree.
> There are some other
> factors of which Richard Kirk's post hinted, for example the
> interesting halation produced
> by vidicon cameras, which is very difficult to replicate with
> modern equipment; the
> interesting grayscale (with low contrast!) of kinescope images.
> As a child I too was
> prevented from watching TV with the room lights down; the patriarch
> said "it will ruin
> your eyes!"  of course he also thought reading in bed would ruin my
> eyes, when actually
> it just ruined my sleep.
>
> Instead of removing color from an image and leaving a low-contrast
> black and white image,
> I think for a moment of adding color to a medium-or-high-contrast
> black and white image,
> which is done with toning and tinting.  Toning and tinting, done to
> photographs, (forgetting
> colorization of moving picture film) can be pleasing to the eye,
> when it is done with
> low or very low saturation.  There is a connection between color
> and contrast that seems to
> be in some kind of inverse ratio, depending somewhat on the
> artistic taste of the viewer.
>
> --Rob
>
> --
> Rob Lingelbach
> http://www.colorist.org/robhome.html
> rob at colorist.org  rob at lingelbach.us
>
>

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