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>>> Overscan, make it stop! :( <<<

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Cheezmo is offline Old Post 05-22-2004 10:59 AM
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Cheezmo
Senior Member

Registered: Apr 2004
Location: Plano, TX
Posts: 229

Everyone should be aware of a few things with regard to overscan.

On RPTV's especially, it is typical to have more horizontal overscan than vertical. Almost everyone I calibrate, involves decreasing the width to correct this.

Every TV screen is not exactly 16:9! Measure yours and see.

Now, my overscan was calibrated with an Accupel HDG-3000 test pattern generator and an overlay grid. I am convinced that my geometry and linearity are very accurate.

So, what does the HDNet pattern show me?

The circle in the middle is exactly 47cm high and 47cm wide. Good.

Anywhere I measure 3 of the squares on the grid pattern, they are 20cm high (or across). Good.

Overscan is just over 4% on the top, 6.5% on the bottom. OK, slightly offset but my grid may have been slightly offset that way, and vertical positioning often varies a bit for different DVD players/STBs.

Overscan on the left is 10%, overscan on the right is just barely under 10%. That can't be right, can it?

This confuses me. The circles is round. All the squares are square. Why is the geometry off. I measured my screen and it is 16/9.04. That shoudn't make it different by more than 1%.

So, where is the problem? Counting the grid they use, it is 27 squares by 15 squares. Huh? That is 16.2x9. This is getting interesting.

They appear to be marking the "numbers" as 1/8 of a square. Um, but look at the bottom ones? They go 14, 12, 10, then a line, then 8, 6 , 4... Whoops, they skipped one! Sure enough, the last one before the edge is 4, not 2. So, subtract 2 from all your bottom overscan numbers, please. OK, now I'm just over 4% top and 4.5% bottom. That's better.

Well, we normally consider overscan in terms of percentage of 100% of the picture. 1% cuts off 1%. This pattern does not represent that!

Horizontally, there are 27 squares. So their numbers actually represent 1/216th's not percentages. So, multiply the left and right numbers by 100/216 to get an actuall percentage. My 10% is now 4.6%.

Vertically there are 15 squares. So their numbers actually represent 1/120ths, not percentages. My 4% and 4.5% are now 3.3 and 3.75%.

OK folks, here is the way to get actuall overscan numbers from the numbers on the HDNet grid (probably worth a seperate post!).

Top: HDNet# * .83
Bottom: (HDNet# - 2) * .83
Left and Right: HDNet# * .46

Wow, I really never would have thought that they would have botched that pattern so badly. How many people are using it to make the top/bottom and left/right numbers the same. Doing so is a bad thing!

__________________
Steve Martin
ISF Calibrator
Smart Calibration, LLC

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MNTivoGuy is offline Old Post 05-22-2004 07:26 PM
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MNTivoGuy
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Registered: Oct 2002
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Steve:

From the factory, my Sony 34 XBR 910 was showing 14s on the left and right and 6 top and bottom. I set to 4 all around. Where should I be reading top and bottom/left and right?? thanks!

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Cheezmo is offline Old Post 05-22-2004 07:46 PM
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Cheezmo
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Registered: Apr 2004
Location: Plano, TX
Posts: 229

If you have 4 top and bottom, that is really 4 top and 2 bottom. So, you should shift it down a little to get 3 and 5. Then you should set the sides to about 6.

If you are set on leaving the sides at 4, you would go for 2 at the top and 4 at the bottom, but I bet you would start getting pretty distorted geometry if you tried to go for overscan that low on that display.

I guess a general rule for using the pattern would be, to use the top number as a rough overscan estimate.

Set the bottom to top + 2. (Of course that only works when setting it to 8 or lower).
Set the sides to top * 2.

So, for 3% overscan, that gives 3 on the top, 5 on the bottom, 6 on the sides.

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ISF Calibrator
Smart Calibration, LLC

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MNTivoGuy is offline Old Post 05-22-2004 08:08 PM
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MNTivoGuy
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quote:
Originally posted by Cheezmo
If you have 4 top and bottom, that is really 4 top and 2 bottom. So, you should shift it down a little to get 3 and 5. Then you should set the sides to about 6.

If you are set on leaving the sides at 4, you would go for 2 at the top and 4 at the bottom, but I bet you would start getting pretty distorted geometry if you tried to go for overscan that low on that display.

I guess a general rule for using the pattern would be, to use the top number as a rough overscan estimate.

Set the bottom to top + 2. (Of course that only works when setting it to 8 or lower).
Set the sides to top * 2.

So, for 3% overscan, that gives 3 on the top, 5 on the bottom, 6 on the sides.



Thanks! I am new to this, and trying to learn. Is 3% acceptable? Too much? I never noticed a problem with the factory settings until i started here! What percentage of overscan was my set at from the factory? Would it be best to set top to 4, botton to 6 and sides to 8 to ensure proper geometry? Thanks so much!

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Cheezmo is offline Old Post 05-22-2004 08:13 PM
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Cheezmo
Senior Member

Registered: Apr 2004
Location: Plano, TX
Posts: 229

Yes, 4 is a pretty safe way to go, but if you can get less with the grid lines staying straight, go for it. The things to look at when you go too low are bending of the lines near the corners, dynamic convergence errors in the corners (white lines having red/blue fringes), etc.

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Steve Martin
ISF Calibrator
Smart Calibration, LLC

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buckeye1010 is offline Old Post 05-22-2004 11:24 PM
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buckeye1010
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Registered: Dec 2002
Location: Dayton, OH
Posts: 423

Steve - thanks so much for figuring this out! My ISFer (Chad Billheimer) used the same generator as you did. I've been waiting to here a good answer on this before I sent him back out.
When I do your math, Steve, my HDNet numbers come out to 4% +/- 1% - just as Chad had quoted me! I can sleep well at night.....

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Buckeye1010 - Dayton, OH

Monitor: 65" Mitsubishi 65611 - ISF'd | Receiver: Yamaha 5590 | Speakers: Polk RM7300 | DVD: Panasonic CP-72 | Sony SAT-T60 (280GB & Cachecard) | "Hughes" HR10-250 (550GB) | VHS: JVC SVHS | Plus a bunch of old stuff dating back to 1918

Last edited by buckeye1010 on 05-22-2004 at 11:33 PM

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Cheezmo is offline Old Post 05-22-2004 11:36 PM
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Cheezmo
Senior Member

Registered: Apr 2004
Location: Plano, TX
Posts: 229

Hopefully I've saved quite a few calibrators calls from their customers who look at the HDNet pattern after a calibration and wonder why their overscan is so bad! I feel really bad for all the people who have set their overscan with this pattern, too! I did email Mark Cuban, hopefully they can get an improved pattern up there before too long.

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Steve Martin
ISF Calibrator
Smart Calibration, LLC

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jrock is offline Old Post 05-22-2004 11:41 PM
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jrock
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Registered: Aug 2002
Location: Connecticut
Posts: 424

I still don't know what I should do. It seems I can get rid of Over Scan or get rid of the scrolling white line but not both. How long is the warranty on the Sony's? Also does it void warranty if you go into the Service menu and play with the settings?

-Joe

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Cheezmo is offline Old Post 05-23-2004 12:51 AM
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Cheezmo
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Registered: Apr 2004
Location: Plano, TX
Posts: 229

I've revised things a bit in reference to to this image.

The pattern extends a bit below the bottom of the last row of squares so the "numbers" on the bottom are reasonably OK (at least from 8 down). You don't need to subract 2 from the bottom number. I also have to adjust the vertical scaling a bit which yields...

Top and bottom: HDNet# * .82 = overscan %
Left and Right: HDNet# * .46 = overscan %

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Steve Martin
ISF Calibrator
Smart Calibration, LLC

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MNTivoGuy is offline Old Post 05-23-2004 01:06 AM
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MNTivoGuy
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Registered: Oct 2002
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quote:
Originally posted by Cheezmo
I've revised things a bit in reference to to this image.

The pattern extends a bit below the bottom of the last row of squares so the "numbers" on the bottom are reasonably OK (at least from 8 down). You don't need to subract 2 from the bottom number. I also have to adjust the vertical scaling a bit which yields...

Top and bottom: HDNet# * .82 = overscan %
Left and Right: HDNet# * .46 = overscan %



You are way over my head! For us dummies, does that mean i should set the top and bottom the same, and the sides at double the top and bottom using this pattern, i.e. 4 on the top and bottom, 8 on the sides, or 2 top and bottom, 4 on the sides, etc etc...Thanks!

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Cheezmo is offline Old Post 05-23-2004 01:35 AM
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Cheezmo
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Registered: Apr 2004
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Yes. The actual ratio is 1.8 but how accurate can you really be looking at those lines.

Divide the horizontal number by 2 and you'll be very close.

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ISF Calibrator
Smart Calibration, LLC

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MNTivoGuy is offline Old Post 05-23-2004 02:25 AM
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MNTivoGuy
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quote:
Originally posted by Cheezmo
Yes. The actual ratio is 1.8 but how accurate can you really be looking at those lines.

Divide the horizontal number by 2 and you'll be very close.



Thanks so much for your help. I am always amazed by how patient and nice people are on helping others on this forum. Much appreciated.

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iNerd is offline Old Post 05-25-2004 01:14 AM
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iNerd
HDTV Complainer

Registered: May 2002
Location: Mountain View, CA
Posts: 54

Yah, my thanks too, I actually just calibrated it till it looked ok with a paused image (which, as it turns out, was a crappy job), hopefully tomorrow morning my tivo will record the HDNet pattern and I can get more precise.

Thanks!

__________________
Sony 34XBR800
DTiVo Philips DSR-6000R - 149 hrs
HD10-250 Baby! (fer sale now)
Denon 3801 Receiver
Remote: Harmony SST-659 (yes I tried the MX-700!)

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MNTivoGuy is offline Old Post 05-25-2004 01:31 AM
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MNTivoGuy
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Cheezmo or Video Jan:

I calibrated my set to reduce overscan (4s on the top and botton, 8 on the sides) But, now, I notice the bars bending outward a little at the upper left of the screen, noticeable mostly when watching 4x3 material or an HDNet game with the score in the upper left. I set back to factory settings and it is there as well. Never noticed it before, but I am sure it was there. Now what to do? Now that I see it I can't stop noticing it!!!

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Cheezmo is offline Old Post 05-25-2004 01:39 AM
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Cheezmo
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Registered: Apr 2004
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Most TV's require service mode adjustments to correct geometry problems like that. You can research procedures for adjusting such things at various enthusiast web sites such has Home Theater Spot, AVS Forum, etc. or hire and ISF Calibrator to do that (and much more to make your picture as accurate as possible). You can find calibrators in your area through those forums or directly from http://www.imagingscience.com/.

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Steve Martin
ISF Calibrator
Smart Calibration, LLC

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MNTivoGuy is offline Old Post 05-25-2004 01:42 AM
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MNTivoGuy
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quote:
Originally posted by Cheezmo
Most TV's require service mode adjustments to correct geometry problems like that. You can research procedures for adjusting such things at various enthusiast web sites such has Home Theater Spot, AVS Forum, etc. or hire and ISF Calibrator to do that (and much more to make your picture as accurate as possible). You can find calibrators in your area through those forums or directly from http://www.imagingscience.com/.


Thanks. Is a problem like that something that Sony should fix under warranty? Or is it normal to have it come from the factory with small geometry problems. I hate it that the more I learn, the more problems I notice. Ignorance is bliss!! Thanks for all your help, Cheezmo.

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Cheezmo is offline Old Post 05-25-2004 01:45 AM
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Cheezmo
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Registered: Apr 2004
Location: Plano, TX
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That kind of problem is typical. Depending on how bad it is, you may be able to get your dealer to replace it or get Sony to send out a technician to try to correct it. You never know so it doesn't hurt to ask. Just make sure you can easily demonstrate the issue and explaint to them that you consider it unacceptable.

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ISF Calibrator
Smart Calibration, LLC

Last edited by Cheezmo on 05-25-2004 at 01:56 AM

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iNerd is offline Old Post 05-25-2004 02:15 AM
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iNerd
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I have gotten goodguys to send out a sony tech to fix geometry problems twice now (for free), the first time was for slight bowing at the bottom and just recently to fix 'S' curves on the side of 4x3 material on my 16x9 set.

__________________
Sony 34XBR800
DTiVo Philips DSR-6000R - 149 hrs
HD10-250 Baby! (fer sale now)
Denon 3801 Receiver
Remote: Harmony SST-659 (yes I tried the MX-700!)

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chriscic is offline Old Post 06-02-2004 08:04 AM
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chriscic
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Lots of overcan on HS10

I'm running my HDTivo to my Sony HS10 PJ via DVI and get bars # 12 on the sides and 6 on top and 8 on bottom. Believe based on prior post that this translates into about 5% overscan on the sides and top.

No way to adjust this on the HS10 that I know of. It kills me that the path from satellite to recording device to PJ is all digital, yet I still have significant overscan. Why this nonsense?

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Cheezmo is offline Old Post 06-02-2004 08:30 AM
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Cheezmo
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Registered: Apr 2004
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The overscan on the HS10 projector is adjustable in the service menu. You should be able to find a local ISF calibrator that could help you out or if you are comfortable making that kind of adjustment yourself you can probably find the info you need on one of the home theater enthusiast WWW sites.

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ISF Calibrator
Smart Calibration, LLC

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>>> Overscan, make it stop! :( <<<

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