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Discussion Starter · #1 ·
What can a single pixel do at a particular instant? It can only be one color can't it? and only one brightness level? What else is there? Isn't all "detail" created by the differences between two adjacent pixels?


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JHouse, a pixel can only be on or off, it can not even be a color. In your PJ, there is one panel for green, one for blue and one for red. The panels or pixels themselves don't produce the color, the color light is shined upon them. If I am totally wrong, I apologize but I believe that is how it works. Just open or closed.
 

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Discussion Starter · #3 ·
I thought the chip was a color. And that it allowed or blocked a certain amount of light to mix with the other two chips to combine for a single composite color and brightness (for that pixel as shown on the screen).


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Joe,


If we're talking about a displayed pixel, which in the case of a 3-panel projector is the summed effect of the 3 corresponding pixels from each panel, yes, one color at one brightness level.


And you're right, it's only changes that define detail. More pixels lets you see more and smaller changes.


If you want to get philosophical, it's been said that perception is not possible without differences/changes. Imagine if everywhere, and all the time, there was only one color, one brightness, one temperature, one taste, one smell. All would be imperceptible.


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"LCD (liquid crystal display) projectors usually contain three separate LCD glass panels, one each for red, green, and blue components of the image signal being fed into the projector. As light passes through the LCD panels, individual pixels ("picture elements") can be opened to allow light to pass or closed to block the light. This activity modulates the light and produces the image that is projected onto the screen"


-Projector Central
 

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Discussion Starter · #6 ·
Okay,...thats good. Now, if all that is true, what is all this talk about the detail being contained in the high frequencies? And that the "sharpness" control boosts or decreases high frequencies. My real question is "how do these high frequencies (which can apparently be adjusted) translate into something I can see?" What are they doing to the pixels or the differences between pixels or the speed at which the pixels change? I don't get it, but I certainly see it.


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Joe

My current idea of the best value:

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Da-Lite 100" 4:3 1.3gain

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and some other stuff.
 

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If you were to look at a low frequency image like a big (4 x 4) checkerboard image, you would not see much detail.


Essentailly, the more transitions in a horizontal line you have, the higher the frequency. The highest possible frequency you could have is an alternating pixel pattern (on off). the ability of a "system" to resolve this pattern cleanly is what we call bandwidth. The top of Stone Cold Steve Austins head has very little detail, this is because the frequency of the information that defines his head is very low. On the other hand, the top of Julia roberts head has alot of detail due to all the fine strands of hair. So, if we were to look at that portion of the video signal we would find that it is a very low frequency.


Remember, the horizontal and vertical frequencies of video signals are fixed at either NTSC or whatever our scaler or HTPC is putting out. The Video (or signal) frequency (SF)however varies depending on what we are looking at. Black screen, low SF, Very "busy screen" high SF
 

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Discussion Starter · #9 ·
First, I can't read slow enough to understand what you're saying Dizz. I could really use a little easier or more concrete explanation. Second, has something funky happened to this thread? Mine is all wonky.


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Joe

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Joe,


Let's suppose we had one horizontal line that had 100 pixels

on it. Now, let the first 50 be "off" and the next 50 be

"on". In our 100 pixels, there was only 1 "change" from

"off" to "on".


Now let the first 25 be "off", the second 25 be "on", the

third 25 be "off" and the last 25 be "on". There would be

3 transitions in 100 pixels then.


Now let's go to the extreme - the first pixel is "off", the

second is "on", the third is "off" - every pixel has a

different state from its neighbor.


There would be 99 transitions in 100 pixels in that case.


So the frequency is how fast the pixels are changing -

1, 3, ...99 per 100 pixels in the example above.


Greg

 

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Discussion Starter · #11 ·
Okay, so higher frequencies(added sharpness) make the adjacent pixels more different from each other? and reducing sharpness "homogenizes" them? So you get the same pictures (at the same rate I presume,in that they renew at a fixed scan rate or refresh rate or whatever), but with greater discrepancies between the pixels? Well are those discrepancies limited to color and brightness?


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Joe

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Boxlight 38t

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Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 

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Exactly. The more difference between adjacent pixels, the higher a frequency those pixels are representing.


Andy K.



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Exactly. The more difference between adjacent pixels, the higher a frequency those pixels are representing.


This is why Frank is claiming detail superiority for Digital projectors over CRT. In theory, adjacent pixels on a digital projector can be completely opposite, everywhere on the image (Of course, light spill works against us here). A CRT, on the other hand, because it generates continuous horizonal raster lines, takes a finite, measurable amount of time to change levels between adjacent 'pixels'.


Andy K.



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Discussion Starter · #14 ·
Thanks everyone. But now you've got me thinking (which is dangerous). Less detail can look smoother and more uniform. I first noticed this when I got DSS at it's introduction (on an RPTV). It seemed as if it averaged and smoothed the picture, making it more attractive. Kind of like some folks liked the sounds of cassettes over LP's because of that "smoothing" of the extemes. Is that why turning the sharpness down improves the homogeneity of the picture. I don't notice is loss in true detail, I can still see the pores in the skin and individual strands of hair, etc.


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Joe

My current idea of the best value:

Boxlight 38t

Quadscan Elite

Panasonic RP91

RCA DTC-100

Da-Lite 100" 4:3 1.3gain

Studio Experience SE616's

and some other stuff.
 
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