On 6/3/2013 1:07 PM, Arfa Daily wrote:


"William Sommerwerck" wrote in message
...
I would also dispute that a black and white transmission
would not look ok if it was a purity problem.

I've been trying to reason this through. The best I can come up with
is this...

Whether purity is good or bad, the electron beams have to land
/somewhere/. In a B&W image, it might not matter much if red winds up
on blue, blue on green, and green on red. The result will be
/something/ approximating a shade of gray.


Correct, as I explain elsewhere in the thread

Arfa

Arfa,

As a newcomer to this group, I hesitate to be a contrarian or appear to
be in any way argumentative or disagreeable. I must admit however that
the notion that random or even partial mis-registration of color is
somehow magically unimportant because the beam has to land someplace
anyway is just totally counter-intuitive and frankly, I believe, wrong.

To make the screen appear white or any non-tinted shade of gray, the
ratio of red, green, and blue is explicitly defined. As soon as some of
the energy intended to light the red phosphor mistakenly lands on the
blue, or any other permutation you may want to consider, the ratio is no
longer producing a shade of gray.

It is certainly obvious when you consider the two extreme limits, one a
single RGB triad, the other the entire faceplate of all triads (stripes)
that if you mis-direct the energy by, let's say, stray magnetism, that
the net effect will be to change the color outcome.Consider these 2
examples:

If, for example, in the single triad case, the red beam was landing on
green rather than red, causing the green phosphor dot to be
disproportionately excited, the color shift would be intuitively to more
green.

At the opposite limit, for the full faceplate, were the red gun's energy
to, somehow, mis-register all of its energy on the green stripes or
neighboring triad dots, the same would be true. The resultant color
would be lacking in red and oversaturated in green.

I use these limit examples as a mental exercise to illustrate my point,
and claim / deduce logically that any example you want to choose in
between will act in the same manner.

If we were talking about power density per square centimeter of energy
being delivered to the faceplate, I would share the conclusion of you
and William, but we are not talking about average power density. The
mis-registration has a consequence when it comes to color purity.

My original and continuing opinion remains that black and white does NOT
mask the purity imperfections as you and William content, but perhaps
this effect is less noticeable because of other considerations (such as
human non-linear ability to perceive chromaticity errors around white
versus our much better ability to discern shades of flesh tones.) This
falls into the murky area of perceptual confusion which allows the brain
and our sensors to easily see some things yet somehow ignore others,
just as is the case for sound and our other senses as well.

I remain fully open to the possibility that black and white does not
reveal purity errors to the same degree for this reason alone, but I do
not in any way buy the argument that mis-aligned / mis-registered
electronics landing on the wrong phosphors is somehow physically
unimportant or invisible due to some odd averaging effect acting to
compensate or some physical phenomena allowing such arbitrary changes in
color proportions to somehow become invisible.