Originally Posted by georule
What puzzles me is the idea of "disabling keystone correction" that joikd references. Darin seems to be suggesting geometry correction is disabled at default delivery of a new set, and any use of the Manual Geometry Alignment option (aka "Keystone Correction") to move any of the 16 alignment points would be "turning keystone correction on", with some good (better geometry on a set with a significantly visible geometry issue) and some bad (loss of 1-1 pixel mapping) in doing so
Sorry, that is not what I intended to convey. I have an '08, so my comments should be taken with that in mind, but at least with the '08 models, they appear to perform geometry correction at the factory, as it has been turned on as default according to most of the posts I've read. I had to specifically go into the service menu and turn it off. Sorry if I confused anyone.
From Darin's explantion, it almost sounds like bkwells should consider restoring his Geometry backup to get his original issue back ...
I've never restored geometry, but I would assume
that it would depend on what the settings were the last time they were saved. It might do nothing, if the service tech saved it after he tweaked it. But I don't know.
Originally Posted by happy nightmares
When he says "lower resolution"... what exactly does he mean? Not getting full 1080p resolution 'sounds' scary, but maybe not. What are we really
talking about here?
I tried to explain it in an earlier post, but it's had to put into words. Essentially, electronic geometry correction "distorts" the image electronically, and the goal is to introduce an exact opposite distortion to any optical distortions that physically exist. The problem is, once you do that, pixels in the image no longer perfectly map up with their corresponding pixels in the imager (DLP). So interpolation has to be done, which robs resolution, or fine detail. The best way to see it would be to put up a black/white checkerboard image, with each square being 1 pixel in size. Once you distort the image, a white pixel may not fall exactly
on a physical pixel in the display, so interpolation has to be done to figure out what to produce on that specific mirror to best duplicate the original image. Essentially, a single pixel is trying to reproduce parts of multiple pixels. The resulting image would look like a checkerboard where the image pixels fall exactly on the imager pixels, but some areas of the screen would look gray. In a moving image, moire is a common effect that is visible when you don't have 1:1 pixel mapping.
Is it only the difference of having overscan, or not? (For that matter, where does overscan play into all this?)
Overscan is optically (physically) inherent in these displays. The fact that there are displays out there with geometry issues is proof that they can't build these sets with PERFECT geometry. You just can't build something this big, made out of plastic, mirrors, and lenses, projecting an image at extreme angles, with ZERO tolerance for error. They couldn't even do that with the Hubble, and it was much more expensive.
So the projection path is designed such that there is overscan, because on the vast majority of content, geometry issues aren't very noticeable as long as the resulting image has flat edges. If there are wavy edges, it becomes much more noticeable. Overscan is a way of "hiding" geometry imperfections. I don't know if the geometry menu has enough adjustment range to bring overscan down to almost zero, but obviously, if you could, that would destroy 1:1 pixel mapping. You would essentially be reproducing a 1920x1080 image on something roughly similar to an 1824x1026 display.
... compared to the very best Plasma or LCD panels, the DLP's image is a little softer, and the blacks a little lighter, but I should stress "little" because it's still very good.
Agreed. If looking strictly at image quality, a good plasma is a little better than DLP. No geometry issues, almost 180° viewing angle, and maintains contrast in brighter rooms better. But the "softness" of DLP is a double-edged sword. That's mostly due to the wobulation, which also tends to smooth jaggy lines (diagonal lines appear
straighter as opposed to jagged). Because if this, DLP doesn't have screendoor effect. There are pros and cons to all display technologies. We have a 42" plasma in one room, and the 73" mits in another, and the mits is by far the preferred display to watch. It's MUCH more immersive. The best way I can describe it is: the plasma looks better if you're looking at the screen, and the DLP is more enjoyable if you're looking at the content.
Originally Posted by georule
Now, re 120hz and "judder", or "avoiding 3-2 pulldown". The consensus I've seen is that Mits 120hz DLPs do NOT do this, unlike 120hz LCDs, because of an arcane term known as "wobbulation" in creating the 1080p image on a Mits DLP.
Every time I say this, people get all up in arms and don't believe me. But no RP-DLP is a true 120hz display. They are
displaying a set of pixels from the image 120 times a second, but due to wobulation, each set is only half of the pixels. RP-DLP displays can refresh the entire image every 60th of a second. That's why they can't do 5:5 pulldown to eliminate judder. Their "smooth 120" feature does some interpolation to modify motion effects, and might even do it on the sub-frame level (so the fact that half of the pixels are displayed 120 times a second may still be a benefit). But it's not the same as having a true 120hz refresh rate.
Ok, throw rocks at me. Everyone else does when I say this.