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Discussion Starter · #1 ·
Banding shows up on all digital sets to some degree,

DLP, LCD, and direct view LCD and plasma,

but very little, if any, on analog tube sets.


If you have wondered what it looks like, here's some samples from a DLP.

The display should show a smooth gradient but instead you get...

http://www.pbase.com/jackcnd/image/47564471
http://www.pbase.com/jackcnd/image/47564485


Adusting the picture mode and setting can help.

It shows itself in peoples faces, the sky, etc.


Anyone have any suggestions to decrease it?


Heres some test images to try if you have a PC hooked to your display.

http://www.pbase.com/jackcnd/display_tests
 

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What DLP set are you using?
 

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I've found out that banding really varies a ton depending upon what you are watching. HD channels that tend to be bad with breakup (like my abc local station) tend to show more banding than hdnet or the inhd channels. The banding is always just in the darker areas though. On dvd's the only place I've seen it has been on the Finding Nemo dvd. Really really visible there.
 

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Discussion Starter · #4 ·
The sample shots are from a Panasonic DLP, its actually not that bad. Its one of the few rear projection sets that offer 1:1 pixel mapping over HDMI.


If the color wheel speed is off, it becomes a real mess.


If others could post pics using a gradient it would be great to compare.
 

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That set needs some serious help with its grayscale. The first greadient (I assume WARM setting) has a blue upper end, red mids and green low end. The second gradient (COLD ?) goes from blue to probably immeasurable. I'm surprised at how clearly delineated you can see those color temperature changes in the first gradient.
 

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That set needs some serious help with its grayscale. The first greadient (I assume WARM setting) has a blue upper end, red mids and green low end. The second gradient (COLD ?) goes from blue to probably immeasurable. I'm surprised at how clearly delineated you can see those color temperature changes in the first gradient.
 

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JackLT; very interesting utility. Where did that come from?


Is banding always vertical?
 

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Discussion Starter · #8 ·
Quote:
Originally Posted by LMDA1
That set needs some serious help with its grayscale. The first greadient (I assume WARM setting) has a blue upper end, red mids and green low end. The second gradient (COLD ?) goes from blue to probably immeasurable. I'm surprised at how clearly delineated you can see those color temperature changes in the first gradient.


Its hard to get a "true" color picture of the image

as seen due to white balance settings on the camera.


I guess I could work on that, but just wanted to show the banding issue.


I was changing the picture mode from cinema to vivid,

as banding is much more prevelant using high contrast settings.


If I get the camera WB to match the colors seen on the set, I'll post some more.
 

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Quote:
Originally Posted by videobruce
JackLT; very interesting utility. Where did that come from?


Is banding always vertical?
The banding is typically directional depending on the gradient. If the color fades from top to bottom or vice versa (blue sky fades to white) the banding shows as horizontal. If the color fades left to right or vice versa (as the test images show) the banding shows as vertical. On images such as a candle in a dimly lit room the banding can show as rings around the flame progressing outward.
 

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Quote:
Originally Posted by JackLT
If the color wheel speed is off, it becomes a real mess.
This is interesting. I go through long periods where the banding is non evident and then out of the blue I'll start seeing it again for brief periods. It makes me wonder if the color wheel speed is being affected by voltage. I live in an old apartment with only two 15 amp circuits. With two air conditioners, a refrigerator, a computer etc I wonder if I'm starving to TV of voltage on occassion and affecting it's performance in that way.
 

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Quote:
If the color fades left to right or vice versa (as the test images show) the banding shows as vertical.
Isn't this grey scale tracking??
 

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JackLT - I know my Panasonic DLP would look similar to your pics. Any other brand DLP owners with HTPC care to post a few pics?


I'm not sure if this is grayscale tracking or not. I know that if I'm in the Panny's service menu, you can adjust color wheel sync with backdrops of red, green, blue, or green gradients. This type of false contour or banding is quite visible in the green and gray gradients on my set, and not hardly visible in the red or blue - does that say anything about whether its grayscale or not?? One of my uneducated theories (i.e. pure guess) is that it might be somehow related to how shades of green or gray might be displayed using the dark green segment on the color wheel as opposed to components of RGB. It seems to me like the transition between the two might result in banding if not done correctly.


A nagging question on my mind (and others I believe) is to what extent can this artifact be calibrated out.


Ben
 

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Quote:
Originally Posted by dingJam
JackLT - I know my Panasonic DLP would look similar to your pics. Any other brand DLP owners with HTPC care to post a few pics?


I'm not sure if this is grayscale tracking or not. I know that if I'm in the Panny's service menu, you can adjust color wheel sync with backdrops of red, green, blue, or green gradients. This type of false contour or banding is quite visible in the green and gray gradients on my set, and not hardly visible in the red or blue - does that say anything about whether its grayscale or not?? One of my uneducated theories (i.e. pure guess) is that it might be somehow related to how shades of green or gray might be displayed using the dark green segment on the color wheel as opposed to components of RGB. It seems to me like the transition between the two might result in banding if not done correctly.


A nagging question on my mind (and others I believe) is to what extent can this artifact be calibrated out.


Ben


Have you tried any adjustments to the color wheel sync to see if it has affected the amount of visible banding?
 

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I don't know if I would really want to try that. :(
 

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Quote:
Originally Posted by toenail
Have you tried any adjustments to the color wheel sync to see if it has affected the amount of visible banding?
Yes - a number of us have and had some success at least reducing the effect to some extent - not eliminated though.
 

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Quote:
Originally Posted by dingJam
Yes - a number of us have and had some success at least reducing the effect to some extent - not eliminated though.
Now I'm curious about whether or not this feature is offered within the service menu on my TV. The fact that mine seems to come and go suggests that an adjustment to the sync won't help under all circumstances, so it may not even be a viable solution to the periodic banding that I experience.
 
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