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Measuring ANSI CR & Checkerboard Patterns
During the recent discussions regarding the Full On/Off CR performance of the Sony VPL-HS51 a tangent discussions regarding ANSI CR came about. In that tangent discussion there was consideration for moving from a 4x4 B&W checkerboard pattern to a 16x16 pattern in order to measure the four center blcoks as it would afford a black block to be surrounded by white blocks.
Now, I use the term block instead of square because I think something needs to be addressed here. The Sony VPL-HS51 does not have a 1:1 aspect ratio panel, but rather a 16:9. In fact, I do not personally know of any digital projector that has a native panel with a 1:1 aspect ratio.
As such, my concern depends on what the checkboard pattern actually looks like, dimensionally. I mean, are we measuring from perfect squares, rectangles, squares with borders outside of a 1:1 section containing a 2nX2n pattern, or what?
Also, I mentioned in one of the Sony threads about what happens measurement readings when the 2nX2n patterns changes from n=1 to 2, 3, etc. since the size of the squares get smaller but the aperture of the measuring device remains constant. Also, as n approaches infinity the result is effectively no longer a black AND white pattern, but a gray pattern.
Now, some would think they would not see a benefit from going with a pattern where n is large, but then I wonder about the fringing effects on the center of a black block compared to a measurement within said black block but close to an edge.
For instance, let's say we had a simple 4x4 square black and white checkerboard pattern. If the detector is placed such that its measuring at the dead-center of a black square and then compares it, say, 10% away from the leading edge of the black square should the measurements differ? I should think so, but I have no means to test this assumption.
If there is a difference then I wonder if this fringing effect increases (assumed it would) as n increases. Ok, enough of my rambling. Its a Saturday morning and I really should go do other things.
Now, I use the term block instead of square because I think something needs to be addressed here. The Sony VPL-HS51 does not have a 1:1 aspect ratio panel, but rather a 16:9. In fact, I do not personally know of any digital projector that has a native panel with a 1:1 aspect ratio.
As such, my concern depends on what the checkboard pattern actually looks like, dimensionally. I mean, are we measuring from perfect squares, rectangles, squares with borders outside of a 1:1 section containing a 2nX2n pattern, or what?
Also, I mentioned in one of the Sony threads about what happens measurement readings when the 2nX2n patterns changes from n=1 to 2, 3, etc. since the size of the squares get smaller but the aperture of the measuring device remains constant. Also, as n approaches infinity the result is effectively no longer a black AND white pattern, but a gray pattern.
Now, some would think they would not see a benefit from going with a pattern where n is large, but then I wonder about the fringing effects on the center of a black block compared to a measurement within said black block but close to an edge.
For instance, let's say we had a simple 4x4 square black and white checkerboard pattern. If the detector is placed such that its measuring at the dead-center of a black square and then compares it, say, 10% away from the leading edge of the black square should the measurements differ? I should think so, but I have no means to test this assumption.
If there is a difference then I wonder if this fringing effect increases (assumed it would) as n increases. Ok, enough of my rambling. Its a Saturday morning and I really should go do other things.
