[photoflow]

I have what I think is a simple question: What is the primary difference between a plasma with square vs. rectangular pixels? I am asking this question because of another post that I saw on this forum. Basically, one of the plasmas that has peaked my interest is the Panasonic 42PHD7UY. This plasma has a resolution of 1024 X 768, which I think is the perfect resolution for displaying a PC signal. However, I saw on another post that this display isn't good for computer signals because it has "rectangular" pixels! I'd appreciate any feedback as to "why" it may be true that rectangular pixels are bad?!?...........I don't get it?!? Which plasmas have square pixels and are square pixles better?!?

 

[vman41]

Multiply the lines of vertical resolution (e.g. 768) by the screen format expressed as a ratio (e.g. 16x9 -> 16/9) and divide by the horizontal resolution. If the result is 1, then the pixels are square. The panasonic would appear to have recatngular pixels (768*16/9/1024=1.185) 18.5% wider than they are tall.


For computer displays, square pixels might make some geometry transformations easier and 1-pixel wide lines are a uniform size regardless of whether they are vertical or horizontal.

 

[photoflow]

Vman, thanks for the info. However............does this mean that I definitely shouldn't use a rectangular pixel plasma as a computer display? Will my eye "really" notice a huge difference between square and rectangular displays that clearly shows that rectangular is "bad", or is it mainly better from a technical perspective to have square pixels? Any feedback is greatly appreciated!!

 

[vman41]

I don't know the right answer, though given a choice I'd go with square pixels over non-square pixels (techincally squares are rectangles). I think the display drivers on Macintoshes can be adjusted to account for the pixel aspect ratio, but I don't know about Windows.

 

[SoSo]

The easiest way to understand it is looking at a diagonal line. Imagine a line draw diagonally from the lower left hand corner to the upper right hand corner. If the line is a perfect 45 degree angle line, the square pixel display will in fact show a perfect 45 degree angle. However, a rectangular pixel display will show a line that is less than 45 degree. (In this case, a lot less.) Thus you will see everything being "short and fat". It is because for each unit (inch, cm, ... etc.) that goes across, only 0.844~ unit goes up (1/1.185).


Therefore, they are not very good computer display because no matter how you adjust your pixel setting, you still have that inherent problem.

 

[bart745]

At 1024x768 input resolution, you will probably notice the stretch. Other than the geometric distortion, the only other ill efect is that the apparent mouse speed differs along the X and Y axes.


OTOH, if you run your PC at 1280x768 (assuming that the Panny will accept it), there will be only negligible stretch. Depending on how the downscaler works, you may lose pixels (looks fine on my Pio 4340HD).

 

[photoflow]

This is great information! Has anybody else out there tried using the Panny PHD7UY as a computer display outputing 1280 X 768?

 

[bart745]

Quote:

Originally posted by photoflow This is great information! Has anybody else out there tried using the Panny PHD7UY as a computer display outputing 1280 X 768?

According to the manual, it doesn't support 1280x768 (oops) but it does support 720p over RGB. Many PC video cards with latest drivers can output 720p (often listed as [email protected]) = no geometric distortion. Edit: One could also try [email protected]

 

[SoSo]

Quote:

Originally posted by photoflow This plasma has a resolution of 1024 X 768, which I think is the perfect resolution for displaying a PC signal.

I think he means bypassing the internal scaler by going 1:1 pixel count.

 

[edaly]

There was a post in another thread from a guy who had a 42PHD6UY he used with a PC and he said the aspect ratio distortion on the Windows desktop was quite visible.


I think you could feed the 42PHD7UY panel a resolution like 1280x720 and get the proper aspect ratio, but the signal would be scaled quite a bit and might not give the clearest output. You could do some searches and find PC users with the 42PHD7UY to see if they can give you some first-hand accounts.


The real advantage in using a PC with a plasma is in feeding the panel the signal in its native resolution so there is no scaling going on. As noted earlier though, this only works properly with square pixels.



edaly

 

[SoSo]

That's why I am considering the 50 instead

 

[photoflow]

ok ok, I'm slowly coming up to speed here. Sounds like I will need to go with the 50" Panny, 43" Pioneer, or the 50" Pioneer to get good picture quality from a plasma display. This is definitely something to think about! The 43" Pioneer is more pricey than I wanted to go, but that may be the best choice for me?!?

 

[bart745]

Quote:

Originally posted by photoflow ok ok, I'm slowly coming up to speed here. Sounds like I will need to go with the 50" Panny, 43" Pioneer, or the 50" Pioneer to get good picture quality from a plasma display. This is definitely something to think about! The 43" Pioneer is more pricey than I wanted to go, but that may be the best choice for me?!?

For 1:1 pixel matching mentioned above, the 43" Pio is out. That said, the downsampling of 1280 to 1024 is quite good - I noticed no lost pixels.

 

[photoflow]

Quote:

Originally posted by bart745 For 1:1 pixel matching mentioned above, the 43" Pio is out. That said, the downsampling of 1280 to 1024 is quite good - I noticed no lost pixels.

Bart, do you have the Pio 43" plasma display? If so, then this is good confirmation that this plasma looks great with a PC signal!!

 

[bart745]

Quote:

Originally posted by photoflow Bart, do you have the Pio 43" plasma display? If so, then this is good confirmation that this plasma looks great with a PC signal!!

Why yes, I do.

 

[karlw2000]

I've got a probable unique situation. I have a Philips 42" plasma with a resolution of 1024x1024. This plasma supports both VGA and DVI, but with a max resolution of 1024x768. For a year, I was using my HTPC at that resolution which is strange because that isn't even the native resolution. I had to play around with aspect ratios whenever I used PowerDVD or BSPlayer.


Then just for fun, I tried 1280x768 through the VGA port and somehow the monitor scales the picture correctly. The monitor will report the resolution as 1024x768, but as far as the computer is concerned, it is outputting 1280x768 and now I get the aspect ratio I wanted. Well, actually I would prefer 1280x720, but it's close enough. It absolutely will not work through DVI at that resolution as it just pushes 276 lines off the screen.


DVD's look absolutely awesome now. Don't ask me how it works...and I surely don't know if it will work on other rectangular pixel monitors.

 

[PanamaMike]

Does anyone have HTPC screenshots of a 42inch HD display being fed a 720p signal as well as a native res signal?


Mike

 

[jaybrubin]

i think feeding a 1024x768 signal into a pioneer elite at 72hz will result in a great image for DVD full screen where zoomplayer is managing the aspect ratio...


when you go back to windows desktop set the resolution back to 1280x720 for a standard desktop...

 

[Hawkwing]

Whichever company develops the technology to build and manufacture a 720P native resolution 42" widescreen plasma TV at a reasonable price will probably make a killing.

 

[will792]

Quote:

Originally posted by edaly There was a post in another thread from a guy who had a 42PHD6UY he used with a PC and he said the aspect ratio distortion on the Windows desktop was quite visible. I think you could feed the 42PHD7UY panel a resolution like 1280x720 and get the proper aspect ratio, but the signal would be scaled quite a bit and might not give the clearest output. You could do some searches and find PC users with the 42PHD7UY to see if they can give you some first-hand accounts. The real advantage in using a PC with a plasma is in feeding the panel the signal in its native resolution so there is no scaling going on. As noted earlier though, this only works properly with square pixels. edaly

I used my Panasonic 42PHD6UY with 1024x768, 1280x768 and 1360x768 signal on VGA input. The geometric distortion in 1024x768 is visible but does not affect user interface and web browsing. The 1360x768 resolution has accurate geometric proportions but text becomes a little blurry (I guess scaler introduced distortion).


I even displayed 1280x1024 (by accident) which is not in the Panasonic's list of accepted resolutions. It synced without any problems. I read that DVI input is not as flexible in accepting various resolutions as VGA but never tried myself.


Will