DJQ is absolutely correct.. a rapidly varying color pattern
will be more susceptible to soft focus desaturation. In
image processing parlance, it would be considered a high
frequency signal, changing from one color to another or
from one brightness to another very rapidly. For example,
a checkerboard pattern with a thousand squares, half yellow
and half blue, would appear gray if observed from a
sufficient distance or with blurry vision.
This is the reason when we make completely accurate digital
fine art reproductions, the large prints appear more
saturated than the small prints despite their being
measurably identical.
Seurat was a notable pioneer of pointillism, which used
saturated colored dots at such high frequency that they
merged into more muted tones when you stand back:
http://en.wikipedia.org/wiki/Pointillism
Mondrian did something of the opposite by using large
rectangular areas of primary color to saturate:
http://en.wikipedia.org/wiki/Piet_Mondrian
Large swatches of color used by artists can really blow you
off your ass, like when a pure cobalt blue pigment is used
to paint a large area of blue sky, or a straight out-of-
the-tube orange pigment dominates a landscape of poppies.
The CIE (Commission Internationale de l'Eclairage)
in France developed standards in 1931 for color definition
in an attempt to correlate human visible colors to a
numeric three dimensional coordinate system, and realized
they had to include the viewer's field of view in the
definition. They performed many experiments on I believe
mostly white males (sorry Joy) to determine an average set
of what are known as the CIE Color Matching Functions,
which are essential in designing optical filters for color
measuring equipment (colorimeters). For more on this
esoterica see:
http://en.wikipedia.org/wiki/CIE_1931_color_space
So modern robust color measurement instruments actually
specify either a 2 degree standard observer or 10 degree
standard observer because fovial color perception differs
slightly from average retinal color perception.
Of course, DJQ has explained all this quite well using
English.
dc
herownsourgelatine wrote:
> Here's the deal. If you are looking at a uniform field of a single
> color, it won't matter if
> you have your glasses on or off-- your perception of that color will be
> the same. However,
> if you are looking at a natural scene in which color varies a lot across
> the visual field, then
> having corrected versus blurry vision will have a big impact.
> Essentially, when your vision
> is defocused, then a single cone or small group of cones (the color
> sensing cell type in
> your retina) will be receiving light from multiple adjacent points in
> your visual field. If
> these points have different colors, then those colors will be blended as
> the image blurs.
> You can see this effect another way by taking a slide or video projector
> and twiddling the
> focus knob...
>
> hosg
Received on 2007-06-06 00:23:22