Using TV screens as monitors (how to fix overscan/zoom)

I have a fairly cheap and generic 32″ LG 1080p screen connected to my media computer (a Mac Mini) as a backup to the projector which doesn’t work well during the day time. We mainly use that machine for watching stuff from Netflix (astonishing quality by the way!).

In my office I also have three 27″ Samsung SyncMaster TA550/T27A550 LED screens which I’ve recently used for a very successful little Xbox Halo: Reach LAN party (see left). They appear to be perfectly adequate for gaming despite a 5ms response time. Accepted wisdom is that you need a 2ms response time for gaming, but I think that’s rubbish – humans cannot detect delays of less than about 20ms! I also selected the T27A550 because I wanted 27″ LED screens with VESA mounts on the back – not that many wall-mountable options it turns out!

I also intend to use the three screens in my office for work. In fact I’m typing on one now rigged up as the second screen for my Mac Air; it seems quite happy driving the screen at 1920×1080 via a moshi adapter, while also driving its built in screen. I’ve yet to decide how to drive the other two. I may use a DisplayLink device and my ‘Air or I might get another machine to drive them. I intend to use them as monitoring boards (network ops on one, sales/marketing stats on the other) rather than additional workspace, though it would be nice to have Tweetdeck/whatever open on one too. I have standardised around HDMI as the interface (see below for why I don’t use expensive cables though!).

However, when I first started using the screens there was “overscan” – the edges of the picture did not quite fit. See the picture on the right for what I mean. On the media PC it was mildly irritating and I tried fixing it with the “underscan” setting in the Mac’s system preferences.

This was far from ideal since it lost some of the crispiness. In the end I just accepted that I could not see the status bar on that computer if using that screen – I normally contolled it remotely from my laptop via VNC anyway.

But with the new office screens that was not acceptable. This weekend I invested a bit of time rummaging in the monitors’ options and found the answer: by default they all are programmed to “zoom” slightly. Not sure why that’s the case but it is possible to tell them to just display what they are getting on their HDMI imputs pixel-for-pixel. The image on the left shows the LG with the status bar now visible (ie. no overscan / zoom), without using the computer’s “underscan” facility. I must have navigated around the menus several times before stumbling across the necessary setting, confusingly masked by a picture size/aspect ratio setting of 16:9. Apparently in screen manufacturer land, 16:9 actually means “chop off the edges”. Who knew!

Anyway, on the LG you press menu then go into “Picture Mode” then “Aspect ratio” and change from “16:9″ to “Just scan”. See below:

On the Samsungs it was Menu -> Picture -> Screen adjustment -> Picture Size, then change from “16:9″ to “Screen Fit”. See below:

HDMI cables

As an aside, no I do not pay lots of money for HDMI cables. HDMI is a digital signal, not analogue like with VGA cables, so it makes no difference. It will either work or not work. I have seen one edge case with a cable that was too long, but it would lose sync every few seconds briefly – not some gradual degredation of quality as the morons in shops would have you believe. See this article from CNET on why all HDMI cables are the same for more info!

Posted on March 4, 2012 at 14:57

27 comments

Chris McCray Mar 4, 2012 17:32 How utterly odd. One thought on why TVs may zoom slightly, it may be to remove any spurious odd lines at the top or bottom of the transmission. Very occasionally a PC TV card I've got shows one or two green lines flickering across the bottom of the picture. It may be unrelated, but if there is a conversion issue from old analogue programmes to digital TV format and, for whatever reason, they differ by a line or two, it may lead to odd lines and zooming slightly would then remove them. I am guessing consideranly here, mind!
Robin St.Clair Mar 5, 2012 14:49 I am reading this on a Sony Bravia monitor that is conveniently desk sized, able to be wall mounted and very savvy about being a PC monitor. It offers the option of exact representation of my laptop screen resolution, a slightly stretched version and a stretch out to the borders. As TV/film makers are aware of the overscanning predilection of television set makers (stops customers from feeling cheated and complaining about 29 inch pictures on 30 inch receivers), I use the fully stretched out version without any significant problems; were my laptop to output 1920x1080, then the image would fill the screen exactly with the ability to individually adjust over/under scanning. I guess this is an advantage of so many TV broadcasters using Sony kit.

Even more impressive is the TV's ability to connect directly to the internet, letting me watch iPlayer, YouTube, LoveFilm etc in HD. I can use my laptop as a keyboard, if required, plays USB sticks or media servers and interacts with other wired and wireless devices.

I had intended getting a Samsung or LG monitor, but my requirement for 1080p, IP awareness and a 24 inch screen narrowed the field considerably.

TV manufacturers picked up their nasty habits during the days that 'bottles' were first used to reproduce broadcast signals.
David H Jul 29, 2012 05:42 Thank you! Just got a new LG TV and had been struggling with this.
K17 Sep 5, 2012 01:45 Oh hey switching 16:9 to "Screen Fit" on my Samsung TV did the trick! Thanks for the info! As a note, The NTSC standard overscans so setting your TV to 16:9 makes it assume you are using it as a TV, not as a monitor.
Tom Bates Sep 12, 2012 21:07 Brilliant! 'Just Scan' and it's sorted :)
Charles Oct 8, 2012 20:17 Late to the game, but normal TV signals transmit extra info around the edges, hence the reason for any overscan at all.
Kristin Oct 17, 2012 22:01 For a Sharp TV go to View mode and hit "Dot by dot" instead of "stretch"
Tim Booth Oct 22, 2012 04:32 Thanks, worked great
Dave DiCicco Oct 27, 2012 16:23 I have an LG TV, and your advice to look for "Just Scan" worked perfectly. Thank you! This was a tremendous time saver.
Alfonzo@yahoo.com Nov 12, 2012 12:01 the over scan is not a good option if you go to the source option for Samsung TVs then tools and rename the HDMI source to pc it gets rid of the over scan and quality becomes a lot better in the native screen resolution.
nicely explained is the manufacturers website.
Jim Nov 19, 2012 21:53 just the fix i needed. thanks. Youre a star!
Dekontee Nov 27, 2012 11:10 thank you thank you thank you thank you thank you.
Kevin Maney Dec 14, 2012 03:03 This is the clearest most well explained solution to anything I've ever needed to internet to help me out with. Thank you for that! :)
Rob Dec 30, 2012 01:09 Thank you! I've been using my LG as the monitor for years and suddenly it switched itself back to 16:9 and I spent the last hour messing with display settings before finding this article and fixing it in 5 seconds.
Ivan V Dec 30, 2012 06:34 Thank you!
I had been struggling 3,5 hours with my LG TV and I finally have it properly installed.
I went as you suggested to
Menu -> Picture -> Screen adjustment -> Picture Size
there I selected 16:9 aspect ratio and then I scrolled down to a menu I didn't know was there:
Screen(RGB/PC)->Auto Config
That did it!!!!
Thank you so much for your advice!
A warm hug from Mexico.
Ivan
Vlasta Dec 31, 2012 16:54 "This is the clearest most well explained solution to anything I've ever needed to internet to help me out with. Thank you for that! :) "
Nothing to add - thanks and all the best
Iqbal Bhawana Jan 21, 2013 16:31 Best solution. Hats off
Zach M Jan 24, 2013 07:24 I cant get the option to just scan :( whyyy
Paul Fitzgibbon Feb 2, 2013 18:13 One note.... I am on a Mac, bought Samsung 32 LED 1080 5000 series. In the Mac monitor preferences "overscan" is checkmarked by default. I unchecked it and it shrunk and had over an inch of black all around. Went into Samsung menu to picture options>Size>screen fit..... nothing happened. The fix is to have "overscan" in mac monitor preferences selected. That way "screen fit" will scale down, it will not scale up !!
Geoff Mar 6, 2013 00:34 Ivan V - thank you so much! Finally figured it out after your help. Had to scroll to the BOTTOM of the "Menu -> Picture" screen!
Tony Mar 12, 2013 19:42 Thank you for this tip. I'm using a macbook pro and a 32" samsung and I could not work out why I was loosing the top menu of my mac on the tv screen. Now I can see it by using the Stretch screen. It has however shrank slightly on the sides, but I don't care much for that.
Although my tv is full HD the colours are slightly washed out compared to the screen on my mac, (which is not HD by the way). I take it that that's how it's going to be really..! I fooled around with the settings on the mac and decided that the 1080i setting with the 50Hz for PAL gives me the best results, though no perfect. Any suggestions for this, would be equally helpful...THANK YOU...
katecw Mar 12, 2013 21:29 @Zach are you using a Samsung TV?
Michael Bauers Apr 6, 2013 19:58 Thanks! That was so NOT obvious - and I thought I knew what I was looking for too. Fit to screen, or whatever it's called, did not sound like an overscan setting.
Jason Kinnison-Holmes Apr 14, 2013 16:18 Thanks for the advice on fixing this sort of problem. I tried it on my TV after losing a bit of the picture when hooking up my HTPC to the TV and it worked fine afterwards!
Jovan Jokic May 27, 2013 14:10 Hello.I have a Medion MD20099 32 inch tv.When I use it with my PC (via VGA cable) my screen is fit on the center of the TV(not by the bottom and top edges,but it has black background on left and right).When i'm using it as a TV,my picture is a little bit cut off on edges,but It's much better than PC screen. eg. I can't see the sport scores,or I can see half of the channel sign,I can't see half of the subtitles,etc. I hope you can help me and thanks in advance. :)
katecw Jun 8, 2013 17:59 @Jovan Have you checked that you're in the correct aspect ratio and not zoomed in or anything? I've never owned a Medion TV so I can't really advice. Best bet is to explore all the menu options and buttons exhaustively I'm afraid!
Robin St.Clair Jun 17, 2013 18:49 The overscan issue IS tedious. For me it is resolved by attaching a 1080p Vaio laptop to a Bravia 1080p screen - its ALLLLLL native. And quite lovely with it. Am about to investigate 4K, my failing eyesight appreciates very high definition, my brain rebels at low refresh rates. I bet 4K will take some refreshing.

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