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Discussion Starter · #1 ·
I apologize for yet another AE thread, I am looking for any thoughts/comments from AE or any other LCD projector users regarding individual color stripe elements in LCD pixels.


Here is a link that explains what this means in case you are not familiar with this technology:
http://www.microsoft.com/typography/...ame=%20&fsize=


I have been playing with changing the Effects in my Xp machine from regular to Cleartype (control panel->Display->Appearance->Effects, use the following method to smooth edges of screen fonts ClearType) and walking up to the screen I can clearly see what this article is explaining (take a look at the change in a capital "A"). It seems clear to me that the AE is able to vertically use individual RGB pixel elements, but I was wondering if anybody knew how to approach this more scientifically.


While I was closelly examining the pixels I noticed that the ability of the AE to use individual elements vertically inside a pixel paled compare to its ability to create vertical lines that are _less_ than the height of a pixel, and this completelly baffles me. Try looking at a horizontal black line that keeps getting smaller untill it fades, it's width clearly becomes lesser than the height of the pixel and it can keep on getting thinner untill it disapears. Does anybody know how an lcd pixel can do this? in the vertical effect we can clearly see green and blue pixel elements, but this does not seem to be the case for horizontal lines.


I was also hoping that somebody with a DLP projector can take a look at cleartype fonts and confirm that DLPs are also able to separate rgb pixel elements.

Thank you.
 

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Maybe I'm confused, but I thought the LCD projector, at least the three panel variety, produced each pixel by overlaying the RGB pixels in the same place.


The technology reference in the link is for laptops the have separate, adjacent RGB pixels. The ability to light up just the sub-pixels is very easy, just send an R, G or B signal to the pixel! The technology to calculate which sub-pixels to light up, is the fun stuff built in to ClearType.


Now as for a projector being able produce lines that are less than the height of a pixel, I am not sure that is possible (I do not own an AE-100, but I do own a LT-154 and a KLW-9000, both are three panels LCD projectors - one front and one rear).


Perhaps the screen door (which everyone seems to say is surprisingly good on the AE-100), does not match the pixel layout. For example, they may have been able to squeeze two pixels beside each other vertically, before having leave a gap, this would make the screen door only half as bad vertically. I know my KLW has an offset pixel arrangment that significantly reduces screen door.
 

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Discussion Starter · #3 ·
Cgblack,


I did not think that lcd projectors allowed for RGB differentiation per pixel which is why I was very surprised at how much better cleartype text looks. When I went up to the screen I could see the black letter that was there before with green and blue "highlights" on the sides that do not seem to take up a whole pixel. Of course "does not seem to" is hardly scientific, I am sure there must be a way to confirm wether this is happening, any ideas?


As to the line smaller than the pixel, like you I believe this is not possible and I like the 2pixel per screen door pixel theory (would also explain the other phenomenon. As far as I know the reason screendoor happens is that they need to place controlling hardware between pixels, this creates separation between pixels. Does anybody know how they are stacked?


Can some other owner of AE with htpc take a look at a lowercase "t" with cleartype turned on and confirm wether the horizontal line of the t is smaller than pixel height? On any other projector?


thank you.
 

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I own the AE100 and tried turning Cleartype on/off. I can confirm that mine does *not* in any way compress the horizontal pixels. I looked specifically at the lower-case "t" as you suggested, toggled ClearType on/off and saw no change to any pixel sizes.


Turning on ClearType produced some shading around the black text, but did not change the size of any pixels, shaded or otherwise.


Ken
 

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Discussion Starter · #5 ·
cgblack must be correct then, this must not apply to lcd projectors, just lcd displays.


Just one thing to make sure we are clear, It is not the size of the pixel that would change, but the content of the pixel. It is presumed that each pixel can have only one solid color, are you saying that in your display the horizontal bar on the lowercase t, specifically the part to the left, takes a complete black pixel? Try lowering the font size to see when/if it disapears. I tried looking at it again and to me it still seems to be half a pixel black half white, which does not make sense.


thank you for your help
 

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Discussion Starter · #7 ·
tahustvedt,


anti aliasing is one thing, ClearType is another. The interesting thing about cleartype is that it effectivelly triples the resolution of your lcd display by being able to use the R,G and B components of a pixel individually.


It would be very exciting if we could determine that an LCD projector is also able to handle the individual components of a pixel and everything I have tried with the naked eye does make me believe this is happening on my AE. What I need is a more scientific way to approach this issue and I was hoping somebody in here had some ideas.


The second issue, the one about horizontal lines being thinner than pixel width, is a completelly different issue and one that already one AE owner has disabowed. I am walking up to the screen after making the pixels as big as my room size permits. When I look at the line that crosses the lower case t or, a better example, when I look at the line that fades below Hard Disk Drives in the My Computer folder (xp) I can clearly see the line becoming less than 1 pixel wide as it fades away. As far as I know this is not possible, does anybody else see this or have an explanation for it if you do?
 

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Discussion Starter · #9 ·
It is a pity that nobody else is interested in this. I have now verified to my satisfaction that the effects I described in my first post are real.


The ae is able to vertically use individual RGB components, this effectively triples the vertical resolution. The Ae is also able to use screendoor to display vertical lines that are much thinner than pixel heigth this allows for amazing detail. What it cannot do is combine the two effects effectivelly, so lines that are neither horizontal nor vertical don't benefit as much from these effects.
 

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Hi EdgyLyric,


I don't know how to put it in a scientific way. Wait til you see the AE100 showing high quality 1080i HDTV picture via the VGA port. Now that's a picture really better than 480p...


regards,


Li On
 

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Discussion Starter · #11 ·
Li on, thanks for your post. One of the reasons I started on this was because I saw the difference between DVDs and OTA HD with HiPix. You could theorize that the DVD image is due to practically one to one mapping of dvd resolution to AE, but I could not understand how the OTA HD image was so much better.


I have spent a lot of time with my nose glued to the screen after making the pixels as big as I could (yeah you can laugh, but tinkering is the second most important part of this hobby, just behind saying "mine is better than yours and barelly in front of watching movies). I could clearly see green and hot pink "halos" arround some images, so when I found the above links I thought I had found paydirt. Then I noticed the vertical lines that are so much thinner than pixels and was again confused.


I have no idea how it is done, but this thinner than pixel height lines are created using screendoor! The lines clearly follow the black "Between" the pixels and enhances it so that it becomes a line. This is amazing stuff people, wildly unlikely and I hope somebody with a digital camera can confirm this.


A good place to look at these effects is the PowerDVD player remote, without a DVD in open PowerDVD and take a look at the "greyed out" Menu and Subtitle buttons. Both of them have very faint vertical lines, the Subtitle greyed out button has a line in the center that is perfect to verify this.


To observe the RGB pixel usage take a look towards the Right of the plus and minus volume sound buttons. There are highlights that are obviously created by hot pink dots much smaller than the pixels.
 

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I'm totally out of my area of knowledge here so please excuse me if I mess this up :)


I thought the ClearType thing worked because the RGB elements in a LCD screen were side by side. But in an LCD projector layers the elements on top of eachother using prisms and other neat optical gear. While you could use an B from the pixel to the left of you on an LCD screen to create a "BRG" pixel you would not get the same effect on an LCD pj. Lets say uppercase (RGB) are active elements and lowercase (rgb) are unactive:


An LCD Screen 1x3 line with one active white pixel:

rgbRGBrgb


By subpixeling you can move this a subpixel or two left or right by:

(1) rgBRGbrgb or (2) rGBRgbrgb


However, the LCD pj stacks all RGB elements of a pixel together and you would get two pixels side by side, in case of (1) a blue pixel next to a yellow one. And (2) would produce a turqoise pixel next to a red pixel.


For a projector a white pixel would be: oWo

(1) would become BYo and (2) would be TRo

Where o is black, W is white (RGB stacked), Y=yellow (RG) and T=turqoise(GR)


Would the mind mix those two together or will the bigger size of a projected image and the empty area between the pixels make you see two separate pixels?


>Wait til you see the AE100 showing high quality 1080i HDTV picture via the VGA port. Now that's a picture really better than 480p...


Could it be that the AE100 is really good at downscaling the picture?


Take two rendered scenes - render it at 1280*960 (1) and 640*480 (2). Then scale the 1280 picture down to 640*480 (3) and compare (2) & (3). In most cases the scaled down picture (3) will look better than (2), if the scaling algorithm is good that is, because multisampling from the bigger picture allows you to create a more precise rendering of the image than the native resolution rendered image.


Did any of this make sense?


Just some thoughts as I find this very interesting because I'm aiming to buy a pj (P75) within the next month and hope to be able to get a nice HD picture even if it can't resolve the full HD resolution.


-

Chris

>1 year without a pj. it's sad. really, really sad...
 

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Discussion Starter · #13 ·
Floppo, thank you for your reply! I was begining to think nobody was interested.


I have been trying to find information on how the panny lcd panels are stacked but I have had no luck yet. Since you are the second person to mention that they are stacked it seems more than likely you are correct.


Thanks for the great description of subpixeling, very clear explanation. What I really need to do is get some pictures of this, it is very hard to explain.


Would the mind mix those two together or will the bigger size of a projected image and the empty area between the pixels make you see two separate pixels?


The problem is that neither of those explanations fit. There is no doubt in my mind that the Ae is displaying both vertical and horizontal elements that are smaller than a pixel. In some cases much smaller. I am blowing up the image so that each pixel is big enough to be individually identified. There are green and hot pink (Turquoise?) halos arround images that led me to the ClearType explanation and there are very small horizontal lines that I just can't explain.


I hope an AE user with a digital camera can take a few pictures of the powerdvd remote parts I posted before.

Thank you
 

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Also, if you read that linked page, he states that any sub-pixel rendering algorithm also will have anti-aliasing. Perhaps that is what you are experiencing for the improvement
 

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Will NOT work on three-panel type projectors. Period.

Simple reason - each RGB pixel is overlapped, there are NOT three colour stripes. Take a close look at your screen.


However, if you have a single panel projector, yes, it will work.


Cheers

Heath Young
 

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Yeah, thats what I figured too. 3 panel LCD and CRT projectors will not be able to benefit much from subpixeling other than the aliasing it also provides. DLPs will "suffer" the same fate too as they also have overlayed pixels. It looked good on my IBM laptop at 1600by1200 but looking close I could see red and green "halos" around the text but at working distance - great.


Btw. One way of seeing subpixeling in action is to set the resolution lower than the LCD panels native resolution and let the computer/hardware scale up the picture. At 800by600 stretched to fill the display (1600by1200) it was fairly obvious and ugly :)


It's still an extremely interesting technology.


The panel layout will also have some effect on the results:
http://www.clairvoyante.com/Pentile_Basics4.html


As for the half sized pixels, I don't really know. I hope someone can post a picture at some time. Could the LCD panels have a triangle layout and that cause it too look like it produces halfsized pixels?


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Chris
 

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Edgy -


I think this is very interesting. Why dont you do what floppo suggests, and look at two photoshop images, rendered at 640 x 480 and compare that to a downscaled 1290 x 960. The latter would probably engage the sub-pixeling.


CG
 
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