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adjusting H-Size and V-Size in correct proportion

Jules

Distinguished Member
I can access the service menu on my Sony TV, and I'm ok with tweaking the geometry and position of the picture.

But, I'd like to reduce the amount of overscan by reducing the
vertical and horizontal size of the picture.
However, given that the pre-set values of each are different,
I don't know how to adjust each so that the picture stays in correct proportion.
e.g. if I reduce both by a value of 3, I appear to be making circles appear as fat ovals.

Even using Avia's overscan test signals don't seem to work, as the set doesn't appear to have a perfect 16:9 ratio.
Therefore, if I reduce the overscan so that he 5% marker is just visible each way on the screen, familiar newscasters look like they've been squished horizontally.

Is there any scientifically correct method for adjusting H-Size and V-Size, or should I just forget it and be happy with a centred image that has about 8% overscan?
 

fatbob

Standard Member
Hi,

I found the widescreen enhanced crosshatch patterns quite helpful when reducing overscan on my Sony tv.

Because each of the squares should have the same dimensions on all sides, I reduced "H Size" to minimize the horizontal overscan (resulting in squares that were too tall and thin) and then began to reduce "V Size" until the dimensions of the squares were once again equal on all sides. To make sure I got an accurate end result I used a ruler after each adjustment of "V Size" to make sure the dimensions of the squares were accurate to the millimetre.

I found on my set that although I could reduce overscan by quite a large amount using the "crosshatch and ruler" approach, and keep the proportions correct, some quite bad convergance errors became very noticeable on one edge of the screen, so I had to increase overscan to conceal this, but overall the end result was better than the "out of the box" settings, with overscan reduced to 4% on all sides.

It's not a very scientific method, but I found it did the job pretty well.

If you do make any adjustments in the "geometry" menu, make sure you keep a note of the original settings incase you need to restore the picture to the original settings (ie. you make a total ballsup of things, as I did on a couple of occasions :clown:).

Cheers.
 

Gordon @ Convergent AV

Distinguished Member
AVForums Sponsor
fATBOB's method is pretty good. I would use the circle hatch pattern myself.

You will probably find though that the TV loads up different memory banks dependant on wheher it's PAL or NTSC you are watching so changing NTSC using AVIA will probably have no effect on PAL. You may need to invest in DVE PAL for that.

Also some TV's deliberately overscan as ithe electronics inside is not capable of actually drawing all the picture info on face of the tube. This is particularily true of those who claim to be able to do 1080i (apparently). I don't know of any UK displays that claim this spec but when I last looked at these test patterns on a pile of HDTV's in US it was amazing just how much overscan they were doing.

Gordon
 
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Paul Atreides

Guest
Adjusting Geometry affects the entire beam and is not the correct way to achieve good proportion. You will first want to set desired overscan with Geometry then use Panorama to perfect each mode. This is very time consuming so you must have alot of patience, it's also quite complicated so don't get into this unless you wish to deal with unwanted effects.
 

Jules

Distinguished Member
But if the geometry is really badly set, then overscan will be different in various parts of the screen.
So I would have thought you must set set geometry before and after overscan adjustment.

Anyway, the panorama menu is too risky and for a quick fix to bendy screen corners, the geometry menu is great.

However, if the problem area is in the middle of the screen, then there doesn't appear to be anything in the geometry menu to help.
 
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Paul Atreides

Guest
I was of course only talking about the proportion, geometry is a whole other issue that must be ironed out first of all. If there is distortion, everything you do will be wrong.
 
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