When we speak of perceived contrast, this is more important than some might fathom. Perceived contrast is how our eyes (and therefore our brain) interprets the image. Perceived contrast isn't just all perceived or an "imagined" increase, it is actually in many cases partly an increase in RECEIVED contrast by the the eye in the sense of how it processes it (rather than just a perceptive increase). Now there is also imagined or illusionary contrast (shown below in the image) which can add/subtract to perceived contrast, but illusionary contrast (for lack of a better word), isn't received by the eye at all, it's instead a fooling of the brain. Illusionary contrast is essentially a disconnect between the brain and the eyes. Many of you have seen the checkerboard image to where some squares look darker than the others, even though they are not all dark.
Perceived Contrast = Illusionary + Received
Received Contrast = Measurable (or Actual Contrast) and then altered by the average in our Field of Vision Omni-Directionally as our eyes pick it up through our eyes' IRIS
Measured Contrast = Only the difference in area of light measured to how the meter received it in its given sensitivity, somewhat uni-directional or at least in a small area as compared to our eyes
Received contrast is everything that perceived contrast is, minus the illusionary factor.
Received contrast and measured contrast are of course related, but they are not perfectly equatable.
Received contrast could be somewhat lower than measured contrast because at times we are receiving less of a difference on average across our entire field of vision as compared to a spot measurement from a meter.Illusionary ContrastThe checkerboard illusion, illustrating illusionary contrast. The squares marked A and B are the same shade of gray.
1) Measured Contrast is not the same as the brain and eyes processing contrast
2) The brain processing contrast is not always the same as the eye processing contrast (in the case of illusionary or imagined). See the light could be evenly hitting your eye, but the brain is unevenly processing it. The reason is because how dark the area is around it, our brain then tells you that the checkerboard is darker than the eye received it. The brain was fooled, not the eye.
Illusionary or Imagined Contrast increases perceived contrast, but not measured contrast. Measured contrast increases perceived contrast usually, but not necessarily illusionary contrast.
A light meter and colorimeter takes a small area reading, meaning it is only measuring the contrast of one spot somewhat uni-directionally. Our eyes work omni-directionally within our current maximum field of vision. Thus, the readings would be different if it read the entire room in the same way our eyes do (meaning omni-directional), or if it averaged out the difference of reflective light coming from the walls, in comparsion to the images off the screen itself, and factored in the internal IRIS in our eyes (hence it was able to simulate our own IRIS in our eyes and how we perceive contrast in our full FIELD of vision).
For example, if you wear a visor hat during a very bright sun, that visor blocks the light immediately above your vision, which increases your contrast. The area immediately under the visor get darker increasing the ability of our eyes to receive contrast, but the "measured contrast" remained the same. Only if you measured the light immediately under the visor, would it measure darker than the black level outside the visor.
However, in projectors, light has to be reflected evenly ENOUGH off the screen so that at least to your viewing angle the image looks relatively balanced, otherwise it would distort the image.
My thoughts are simply, it does NOT exist at the moment, not in the commercial public world anyways. However, there have been theoretical light control mechanisms created that can even bend light around objects and create an invisibility field, theoretically. Not that this is related, but it brings a point up to that just BECAUSE something is possible or theoretically do-able, does not mean we actually have that technology in use.
A room with dark gray carpet isn't a bat cave, my feeling is that your screen is preserving and amplifying various amounts of RECEIVED contrast and ANSI, as well as illusionary contrast.Edited by coderguy - 9/11/13 at 11:53am