On Tuesday, April 29, 2003, at 04:22 PM, Rocky Entriken wrote:
>> On Saturday, April 26, 2003, at 12:09 PM, Pat Kelly wrote:
>>> An interesting discussion, esp about red & black. If one is
>>> changing
>>> photos from color to black and white, often red turns into black,
>>> unless it
>>> is a lighter shaded red. I think shades/contrast of colors has a lot
>>> to do
>>> with their readability, light & dark.
>> That should depend on how you do it; if you shoot with a red/orange
>> filter then the red should show up very light; if you shoot with a
>> blue
>> or green filter it will turn out darker, if not completely black.
>> Then
>> there are the electronic versions of the same conversion (if your
>> graphics program allows it, take a look at the individual channels;
>> the
>> difference between the red/blue/green channels can be striking,
>> depending on the subject and the colors involved.
> Unless you are wearing glasses with those filters, the filter
> suggestion is
> irrelevant when discussing color contrast as seen by a timer or course
> worker. Pat's photo example is an example of how colors work, not on
> how to
> shoot pictures.
> --Rocky
Gee, I thought he wrote "If one is changing photos..."
Pat tried to illustrate your point with an example, drawn in this case
from photography. The problem with the example he chose is that it
depends on a number of assumptions, the biggest one that photography
(and the conversion he is referring to) works the same as human vision.
Which it can, sorta, kinda, if you work hard to make it do so. Which
isn't the case in the examples I've seen of the process he described.
So his attempt to illustrate the point doesn't really work.
Colors don't just 'work'. The color of the light source, the color
properties of the media the light travels through from the source to
the object, the color of the object, the color *around* the object, the
color properties of media the light travels through from the object to
the viewer and finally, and often most importantly, the perceptions of
the viewer all go into the pot. Add a couple more iterations of the
whole mess when you are talking about color photography that someone
prints (slides fare a little better, but can still be affected by a
ham-handed developer) and then the person looking at the print.
As an example, a couple of times you have said about red "...but
chromatically it is at the dark end of the spectrum". Which is a
nonsensical statement; the 'dark end of the spectrum' is a lack of
luminance (darkness), not color. You can say you meant that after red
you get infrared, which, since we can't see it, is black, but the same
is true of ultraviolet at the other 'dark end' of the spectrum.
'Chromatically' just means 'having to do with color' (technically,
color when there is enough luminance to perceive it.)
Your example, in an earlier posting, of printers using a red gel to
black out an area in a shot for print is a good example of the problem.
It shot 'blacker than black' because they were shooting using a light
source with little/no red in it and a lot of blue and film that reacted
strongly to blue rather than red. If they had used a light with lots
of red in it and a film like Technical Pan then they would have used a
blue or green gel to get the same effect. And it would have worked
just as well. Not because blue is inherently closer to black than any
other color, but because that is how it works in that environment.
You wrote "In black-and-white photography, red IS black." No, it
isn't. Put a red filter on your camera and then red IS white (and blue
shoots as black). What color you want to shoot as black or white is
entirely up to your film and your filter. You can take two consecutive
shots on a single roll of film and make a red object look black or
white simply by changing your filter. It isn't any special property of
red that makes it so.
Of course, the real corker of this whole tempest (OK, that's
grandiose, how about a short sprinkle?) is that, if you read what I
wrote on color rules in heraldry you'll see that we are actually in
violent agreement on the basic question ("Don't use black on red or red
on black.")
Of course, the real solution is simply to start telling everyone that
the folks going really fast at Topeka all have this secret thing they
do to make their cars faster... they use good contrast numbers on their
cars. Easily makes their cars .050 seconds faster, just look at the
results...
David
Silver car, black numbers.
(For a readable and informative work on the history of color and color
perception, I recommend "Blue: the history of a color" by Michel
Pastoureau (English translation 2001, Princeton University Press.) For
use of filters and film to play with color perception, there is just
too much out there that covers the basic stuff...)
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