I have a 50 87W should I turn it off,,,what does it do if on or off?

Overscan on makes the tv pic a little larger so no lines or artifacts show on the screen edges. It kind of hides any broadcast signal artifacts. It is the setting TV's are shipped with. People who use the tv as a computer screen like it off, others like it off because they think the pic is a bit clearer. For just normal watching of tv and dvds you can leave it alone. If you want it off, check the threads for your TV model for methods to turn it off.

Mes44 answered your question but you can read even more about overscan in a Wikipedia article here (http://en.wikipedia.org/wiki/Overscan).

After you read that article be sure and look at the section in this Wikipedia article (http://en.wikipedia.org/wiki/Native_resolution) that mentions 1:1 pixel mapping. If you turn off overscan, you probably lose 1:1 pixel mapping. Pick your poison.

Google for

Overscan

and you will find lots of links including the one in the above post describing it.

If you can turnoff overscan on the TV/display you can achieve true 1:1 pixel mapping since you will no longer need to apply overscan compensatin by underscaning the PC ouput by deleating about 5% of the rows and 5% of the pixels in each row and then have the display try to reinvent them to give the appearance of 1:1 Pixel mapping. Small font text in PC desktop applications appears blurry when this is done since the pixels invented never match the pixels deleated.

If you can turnoff overscan on the TV/display (emphasis added) you can achieve true 1:1 pixel mapping since you will no longer need to apply overscan compensatin by underscaning the PC ouput by deleating about 5% of the rows and 5% of the pixels in each row and then have the display try to reinvent them to give the appearance of 1:1 Pixel mapping.

Hey walford:

You seem to be saying the opposite of what I stated concerning overscan, 1:1 pixel mapping, and rear-projection displays, so I think I'm getting confused. Maybe I misunderstand and you can clarify.

If I'm reading you right, you're saying that rear-projection DLP displays like y2jared84's Samsung HL-S5087W artificially create overscan by electronically interpolating pixels beyond the display chip's native resolution, and the screen would display 1920 x 1080 pixels on the screen if overscan is turned off. Therefore if he simply turns overscan off on this display you say he'd get 1:1 pixel mapping at 1920 x 1080 resolution on the screen?

It was my understanding that while the DLP's display chip outputs 1920 x 1080 (ignoring "wobulation" for now, which is a whole other discussion!), rear-projection displays optically introduce overscan through the lens system (for the reasons outlined in the Wikipedia article plus other reasons) by projecting those 1920 X 1080 pixels over a somewhat larger area than that of the screen. Therefore, if you have overscan turned "on" you get 1:1 pixel mapping, but something less than all 1920 X 1080 pixels are actually shown on the screen because of the overscan. If you turn overscan "off" you get the "full 1920 x 1080" image displayed on the screen, but fewer than 1920 X 1080 pixels are used to create the image because of the optical overscan (i.e. you no longer have 1:1 pixel mapping). Not true?

There is an involved post here (http://www.avsforum.com/avs-vb/archive/index.php/t-689283.html) that discusses how to use a PC display interface card with the Samsung HL-S5087W to achieve a full screen image with 1:1 pixel mapping (albeit at 1880x1045 resolution). If one only had to " turnoff overscan on the TV/display" in order to "achieve true 1:1 pixel mapping" as I read from your post, why then would the folks in that thread be having so much trouble getting it to work?

(BTW, I don't know that y2jared84 was even thinking about using a PC interface to achieve a full screen image with no overscan with 1:1 pixel mapping, but it was my understanding that that is the only way you can achieve that goal in a rear-projection display short of opening up the display cabinet and moving lenses around.)

Thanks,

kelpie

If it was done with optics it would be done also for the VGA intrerface which it is not.
I have always understood it to done by zooming in on the image as I stated just like other picture size options such as linear or non linear stretch are done. The reason so many people have problems with it because very few HDTVs provide you the option to turn off overscan in Component and HDMI/DVI interfaces. The only DLP model I am aware of is the Samsung HL-Sxx88W. Also I beleive most Westinhouse units have overscan and screen size adjustments And I have been told that some LG LCD Tvs have the ability to turn off overscan.

If it was done with optics it would be done also for the VGA intrerface which it is not.


But the very first line in the thread that I linked discussing the apparently very complex problem described in Zainag's attempts to get y2jared84's type of display to give 1:1 pixel mapping without overscan specifically states:
Connect the TV to the PC using a VGA cable, turn on the PC and TV and set the Source to PC.


Looks like Zainag (who started the thread that I linked and who seems to own the model of display we're talking about) disagrees with you, doesn't it? His VGA interface (which appears to be the same as y2jared84's) didn't seem to give 1:1 pixel mapping with no overscan at 1920 X 1080 by simply turning overscan "off". Best I can tel he had to set the resolution to 1880 X 1045 to get the picture to fill the screen appropriately without overscan via VGA.

Also, one well respected poster on this forum said in the Samsung HL-SxxxxW thread:

Don't buy any RPTV if you do not want any overscan. Video displays are generally designed to have some overscan to hide some problems with displaying information that is transmitted with the video signal that is annoying. Rear projection displays also require some optical (emphasis added) overscan to compensate for slight errors in the projection system. Some displays will allow you to reduce the apparent overscan to zero, but you will then be cramming more lines into fewer pixels because the micropanel position is fixed.(http://www.avsforum.com/avs-vb/showthread.php?p=7959210&highlight=overscan#post7959210) (http://www.avsforum.com/avs-vb/showthread.php?p=7959210&highlight=overscan#post7959210)

Sorry to be so dense, but I'm still confused by your posts I guess. Maybe you could explain further?

Thanks,

kelpie

I have always understood it to done by zooming in on the image as I stated just like other picture size options such as linear or non linear stretch are done.

OK, after sleeping on it maybe I've answered my own question.

Are you saying that y2jared84's Samsung has a software overscan that is "done by zooming in on the image" (that is turned "on" by default out-of-the-box and can be turned "off" in the service menu)- perhaps in addition to the optical overscan typical of RPTV displays? And that with that software overscan "on" you don't get 1:1 pixel mapping, but with it "off" you do?

I can understand the need for "some optical overscan to compensate for slight errors in the projection system" in RPTV's, but a manufacturer seeing the need to then add some software overscan by default (and therefore degrade the entire image across the screen somewhat?) still confuses me.

Best I can tel he had to set the resolution to 1880 X 1045 to get the picture to fill the screen appropriately without overscan via VGA.Are you saying that y2jared84's Samsung has a software overscan that is "done by zooming in on the image" (that is turned "on" by default out-of-the-box and can be turned "off" in the service menu)- perhaps in addition to the optical overscan typical of RPTV displays? And that with that software overscan "on" you don't get 1:1 pixel mapping, but with it "off" you do?This is correct.

The latest Samsung DLPs still have some optical overscan (1-3%, varies by model), but it is significantly less than you see with most other displays. Samsung then applies additional overscan through interpolation, which you can disable in the service menu on the x78/x88 series and x87 models with a December build date.

By comparison, the Sony XBR2 series exhibits 4-8% total optical overscan, i..e. 1780-1820 x 1020 resolution.

I am only referring to Software Overscan or that being done with hardware video processing chips in the HDTV as you suggested to be needed to compensate for physical lens alignment with the screen.
The Samsung units do not overscan over thier VGA input since they assume that you are using a PC and that you may want to use yur HDTV as a PC monitor. The Samsung user manuals have a separate chapter in them devoted to use with a PC and the VGA interface.
If is important to note that the reason that HDTV overscand their TV inputs is that in the early days of CRT TVs the screen image would shrink and the video edges would show after the set warmed up and also over the life of the set due to age/use deterioration of the electro magnets used for the scanning. Therfore CRT sets were adjusted so they would overscan. The TV networks were very aware of this so they would insure that no meaningful content was contained near the edges of the display. NOthing has changed since HDTVs are preset to Overscan over the TV interfaces and the networks knowing this still have no meaningful content near the edges. Because of this overscan is considered a benefit by many when watching TV since the meaningful content is larger in physical size.
Of course the problem comes when trying to run PC applications which have always had meaningful content near the edges and CRT PC moniotrs were best adjusted so as to have a thin border around the edge of the video.
I am happy to hear that more Samsung models now have the ability to dissable overscan in the service menu. Hopefull all of their 2007 models will have this capability and maybe even have the ability as a picture/size option available to the user as they did when using 720p over DVI or HDMI in their HL-P series.
I was not aware that SONY has a large amount of physical overscan in their XBR2 models and therfore you cannot have 1:1 pixel mapping( with slight loss under the bezel) over their VGA interface if they have one.

Here is a summary: :eek:

1. Samsung DLP RPTV sets do have two types of overscan.

The first type is physical and is determined by the relationship between the screen and the light engine (projector). This overscan is just enough to cover most "edge" problems in analog TV broadcasts. In this case, the set is doing a 1:1 pixel map from the input to the screen.

The second type of overscan is added by UP-scaling the image from around 2% overscan to about 5% overscan. That amount of overscan makes it virtually impossible that Samsung's customer service folks will have to deal with owners complaining about the crap at the edges of their image. :eek:

2. The lack of overscan when using the VGA connection is just the reverse of the UP-scaling used to add more overscan to the image. In the VGA case, DOWN-scaling is used to insure that no part of a Windows Desktop is lost.

3. The only time a Samsung owner can enjoy 1:1 pixel mapping is when the UP-scaling overscan is turned OFF, and the source is connected to a HDMI port.

Because of the scaling involved with the other two options, the 1:1 pixel mapped image is sharper. That extra sharpness isn't enough for everyone to notice depending on their eyesight and how they are using their TV.

As for the HL-S5087 model that started this thread, depending on when it was built, the SM overscan may not be able to be turned off. There are reports that HL-Sxx87 sets built in December or later can retain a overscan OFF setting after the set has been turned off.

Maybe the newer models are different.
With my 2 year old 720p Samsung HL-P4663 using the VGA interface with 720p as the resolution from my PC I can select "Expand Mode" which "scales the picture to the aspect ratio of the input source" which since the source is 720p indicates that no scaling occurs and I never see any black bars around the image when I use this mode nor do I see any distoration of small text font lettering edges on the screen using a magnifying glass so I certainly believe I have true 1:1 pixel mapping for that part of the image not under the Bezel.

Maybe the newer models are different.They are starting in 2005. My set is the same as yours. I use Expand mode with HDMI for 1:1 pixel mapping too. If you use Wide(TV) you get the UP-scaled version. If you use Wide(PC) mode you get the Down-scaled version. We "older" owners have the advantage of being able to control overscan with the "psize" button on our remotes. :)

I've never used the VGA connection but you can confirm that you are getting 1:1 pixel mapping by displaying a 720p test image with alternating black and white pixels.

Does anyone know if Vista helps alleviate the HTPC display issues?

Does anyone know if Vista helps alleviate the HTPC display issues?Probably not yet, but what issues are you referring to?

Oh, I mean the overscan issues, that it cuts off the taskbar. I think I understand that to get 'correct' viewing on an HTPC that you have to use something like Powerstrip. I was wondering if Vista has options to fix this.
That is, if I'm understanding correctly!

Oh, I mean the overscan issues, that it cuts off the taskbar. I think I understand that to get 'correct' viewing on an HTPC that you have to use something like Powerstrip. I was wondering if Vista has options to fix this.
That is, if I'm understanding correctly!I will be surprised if Vista has Powerstrip capability built in. There seem to be a lot of Media Center improvements with TVs enabled for Vista in the future. Maybe it will be handled in the TV sets. If they build them with a monitor function that should do it.

Edit: Overscan has no place in an all digital world. :)