back to article Videogame history project successfully emulates CRT on LCD

We thought fuzzy images went out with cathode ray tube monitors, but a team of boffins at the Georgia Institute of Technology have developed an app that mimics the visual characteristics of CRTs on today crisp, pixel-perfect LCD screens. And it's all been done in the interest of historical research, specifically the evolution …


This topic is closed for new posts.
  1. DZ-Jay

    Is this really new?

    Whenever I play with MAME, I always set the visual effects settings to reproduce such artifacts. Playing classic arcade games just doesn't *feel* right with a crisp and shiny LCD (or modern CRT, for that matter!).


  2. Dave Edmondston


    Stella - blurred images. Feedline heaven...!

  3. Neil Boulton
    Thumb Up


    That's quite awesome.

  4. Anonymous Coward


    I know its a long time ago now, and my memory of those days is a bit fuzzy, but I don't remember the screen being that fuzzy any time I played computer games. It looks like someone has wiped the screen with Vaseline. Actually wouldn't that have been easier? Put a bit of dirty glass over the LCD panel?

  5. Ian Bradshaw
    Thumb Up

    AA x16

    AntiAliasing for the 80's! :)

  6. Toastan Buttar


    These guys could probably make a fortune downgrading CD's to crappy vinyl quality for those old-skool 'audiophile purists'.

  7. Bad Beaver
    Thumb Up


    is interesting.

  8. Anonymous Coward
    Paris Hilton


    Next thing will be distored glasses - you too can see what its like to be myopic,

    Limb imobolisation slings - you too can be an amputee

    Lage doses of castor oil - you too can see what it feels like to suffer from irritable bowel syndrome.

    Paris ?

    Only gets distorted by the press - lol

  9. Anonymous Coward

    emulate the sweat or gum on the controller?

    Yes, that's all very well, but how are they going to emulate the following:

    1. kid behind you telling you how it should be played

    2. kids behind you in awe of your skills

    3. Sweaty / broken / chewing gum infested controllers

    4. Dodgy coin slots / various techinques at cheating coin slots (coin on a string etc.)

    5. Surly/Pervy/Dorky/Nasty/Sexy shop keeper / arcade attendent

    6. Inserting coin and getting approx. 3 seconds of gameplay before GAME OVER

    7. Inserting coin and playing till the shop/arcade owner wants to close because your so damn good

    8. Spending all your available cash on gaming

    9. Nicking money from your siblings / parents in order to feed your gaming addiction

    Ah, those were the days...

  10. Simon

    3D next?

    So when we have the new 3D display monitors we have been promised are they going to then also emulate the effect of the old 3D (Glasses) displays which gave you a stinking head ache after about 20 minutes.

    "Yes sir, now after you have loaded the 3D game emulator in you need to wear this on your head, yes sir that is indeed a hammer with nails on it attached to a giant solenoid"

    Happy days playing on the VR machines in the arcade by me so many years ago.

    Holy crap all this old technology is making me feel old now, would you believe there are people today who have never heard of BASIC or Sinclair computers? Yeah you! Get off my laaawn!

    Anyhoo, looking forward to trying out this CRT on LCD for real very shortly.

  11. Dennis
    Paris Hilton

    graphics improvements

    Isn't it slightly ironic that with all us gamers getting bigger and fatter (faster?) graphics cards that their are others trying to recreate the graphics of yester year.

    Everybody remembers old games with a fondness but bringing the old crappy graphics back won't help you recapture that magic. They were of their time we are different animals from what we where then.

    I loved Kalecovision and spend hours playing it when I should have been doing my homework but having 1/4 inch pixels thrown onto the television wasn't what excited me. It was the fact that they were new and exciting worlds and something which I have never even imagined before outside of a book..

    Playing it now just pisses me off because it spoils the fond memories I had. In my minds eye its all 3d graphics with smooth rendering and I don't want to think to them any other way.

    Or maybe I have missed the point which was to see if you can get a modern graphics card to run like a bag of spanners. In that case I could have saved you some time and recommended a few ATI cards which would easily meet your expectations.

    Paris because she is too young to remember Atari and Kalecovision and as so is too young for me! BooHoo

  12. John

    Kids these days

    "while younger players will get to game the way their dads did. "

    But will they want to?!

    Never mind the colour bleed and bluriness, I've shown my 11yo son the games I used to play using a C64 emulator, and he thinks they are totally lame with awful graphics, and 'No thanks - I don't want to play'.

  13. Alex King

    This is such a geek solution to a non-problem

    Do you:

    a) Spend hours and hours of coding, testing and evaluation to emulate, through software, the defficiencies of old pieces of hardware, to achieve an authentic replication of those pieces of hardware using modern kit, or

    b) Go to your local pawn shop and buy an old telly to plug your computer into.

    Sheesh. I suppose with a) you at least don't have to go outside and interact with people...

  14. Nick

    Nothing to see here - move along....

    Emulators have always done this sort of thing (SuperSAI, 2xAA, NTSC filters, 25% Scanlines, etc...).

  15. 4a$$Monkey

    I often find my screen is fuzzy after using Stella

    About 6 cans normally does the tick

  16. Anonymous Coward

    Hmmm I don't think so

    Don't they mean emulating old low resolution TV CRT screens.

    There was me thinking CRTs are in fact better than LCDs but what do i know. The last of the CRT's (monitors) are much better than LCDs will ever be simply because LCDs cannot do black due to it being back lit, not to mention other quirks.

    LCDs are only better because they are smaller and more convienient, which I have to admit is better overall.

    Whatever happened to the flat CRTs :(.

  17. Wize

    One thing it cant emulate

    Reflections on the glass surface of the CRT. Especially on a sunny day with the reflection of a wall being brighter than the screen.

  18. SImon Hobson Silver badge

    But ...

    ... when will they do a realistic vector scan emulation so we can relive Battlezone in all it's (non-jaggy) wireframe glory ?

  19. The Fuzzy Wotnot
    Thumb Up


    My heartfelt commiserations! You're missing out mate.

    I dig out the old Amstrad CPC emu and I fire up Oh Mummy, Roland on the Ropes and I get massive, and I mean huge floods of memories coming back. Yes it all seems a bit rose-tinted, especially when you do it on a crisp 24" LCD, but the memories of many a Sunday afternoon, spent up in my room with a couple of mates trying to fathom out that one last level on XYZ or what commands you need to get through a stage on a Level 9 adventure. Easy days, when all youhad to worry about was making sure your PE kit was in the wash for the following week and you were home by 10pm for school each day, if you happen to move the gaming venue to a friends house.

    Now a sad 40 year old git with house, family and life's problems, but still subscribe to Retro Gamer monthly and I still bore my kids with tales of old bands and old games!

    More power to these guys for time well spent on this silly, project!!!

  20. thomas k.

    @ John

    Haha, yes!

    When Pool of Radiance 2 came out, everyone said it was vastly inferior to the original Gold Box game. Shortly afterwards, the original was reissued (in a Collector set with several similar titles), so I bought it to see just how awesome the original actually was.

    It might have been the cat's pajamas, I don't know - the graphics consisted of little black stick figures on a white background! I promptly uninstalled it.

  21. Charles Silver badge

    Re: Hmmm I don't think so

    Flat-screen CRTs can only be so thick because it's hard to squash a picture tube--electrons traveling at or near the speed of light can only be redirected so much by a magnet.

  22. Stu

    @AC 1/5/09 11:17

    I'll tell you what happened to flat CRTs. They went the way of the dinosaur, quite rightfully so, because to achieve the slimness, they had to accentuate the photon beam geometry so much that if a horizontal or vertical line showed up on screen, be it a banner or whatever, you could clearly see it'll be bent out of shape.

    The best models meant the lines bent out a little, the worst, a helluvalot.

    I know, I had a Samsung SlimFit High Def CRT, believe it or not. It died after 2 1/2 years.

    They were physically shorter in depth, but were the same weight too, my 32" screen weighed a small tonne!

    Bloody awful things.

    Now why didn't these odd programmers who built this CRT emulation system allow you to screw with the geometry too?

    Death to CRT, Long live LCD, esp with adaptive LED backlighting which sorts out deep black levels no end.

    But not too long to slow the arrival of big screen OLED TVs! ;-)

    Bring it!

  23. Chris Silver badge

    @AC 11:17

    As you've already pointed out, low-res TV screens are CRTs, so I don't see there's a problem here - if you're assuming that CRT = high quality then that's your call, but it doesn't mean you're right ;-) *Some* CRTs are high quality, but in the context of this article I doubt you'd have found many 80's gamers hooking up their consoles/8-bitters to anything more advanced than the family TV, and more often than that just a cheap and cheerful portable. They were all still CRTs though.

    As for CRT vs LCD - don't you place any value on the inherent geometric accuracy of LCD screens? Given the choice of spending hours fine-tuning the geometry settings on a high quality CRT, or simply switching on a LCD and getting perfect geometry every single time, I'll take the latter thanks. And with improvements in technology (adaptive LED backlighting, OLED etc.), achieving true black output is just a stone's throw away...

  24. Paul

    been there, coded it, don't remember it like this

    I'm unconvinced these guys know what they're emulating, I've never used a TV RF out as badly artefacted as they show, hope they just wound up to 500% to hilight the effect, its not the memory I have as a user or what I did as a console programmer. Then again I always bought decent quality TV's and that's what developers tested on. Needs a pretty horrible TV to look as bad as they remember.

    Their colour bleed emulation is really emulating (badly) the low pass filtering in the consoles TV encoder (meant to avoid ringing artefacts and generally over aggressive doing it). Yes, it looks like horizontal bleed but it never stretched as far as they've implemented - good for smoothing single pixel gratings and nothing more. A dangerous tool as well, try it with SCART RGB on later hardware and suddenly you discover CRT TV's are perfectly capable of showing crisp sharp edged pixels.

  25. Ian Ferguson


    I do hope for the sake of historical accuracy that they have built in a 50hz flicker that gives you a headache if you sit too close.

  26. Dave Murray Silver badge


    Why would I want an Atari 2600 emulator? I can plug my 2600 in and play Space Invaders any time I want. :)

  27. Mike Silver badge

    TVs for developers

    While it's good to have a few good TVs for developers to use (I still have a 13-inch Sony from those days), we (Atari) used to make sure we also had a number of Bargain Bin (will not mention the mfg, as they do much better these days) TVs, so we could make sure a game was still playable on what our typical customer was likely to have.

    Sortof like when some folks on UseNet suggested passing the virtual hat to get Linus a kick-butt machine for development, to be answered quickly by a chorus of "NOOOooo!" :-)

  28. Mad Hacker
    Thumb Down

    two problems

    The phosphor glow is nice. But they added a screen door effect, which was not usually that bad on CRTs. They failed to eliminate every other scan-line. Often to avoid the flicker of interlacing the games simply wouldn't draw anything on every other scan-line, creating a venetian blind affect.

    But keep trying lads.

  29. MinionZero

    Sorry, that isn't even close to a true simulation of a CRT.

    If this is being done for fun, then ok maybe just maybe its passable, but even then, it makes it harder to play due to eye strain, which detracts from the game.

    However if this is being done for detailed historical research reasons, then they really need to discuss this in detail with old TV electronics engineers, as many of them would be more than happy to help with this kind of historical research. As this simulation isn't even close yet. Its almost totally wrong. Its a lot more like a made up guess of what they think an old CRT should look like, rather than a true simulation of a CRT.

    /Disclaimer: I'm going into deep geek mode, look away now if you are easily scared by such talk. ;)

    For a start, their simulated pixels are too quantized into individual pixels with a boundary of black. It looks like a black grid is around each pixel and then the pixels are poorly blurred with some kind of crude Gaussian blur function over the edges of the pixels into the black. It gives an overly almost cartoon style guess like take on what they think old pixels look like, rather than what they were really like. (They really need to get CRT monitors next to their LCDs to see the pixels don't look like this).

    Also the noise on each pixel looks wrong. Ok the PSUs of monitors and the input analogue signals were not perfect, but they were not that noisy and the phosphor acts partly like a kind of low pass filter on most pixel noise.

    A more common feature / fault / effect on some old analogue monitors was to have some signal mismatch resulting in an effect somewhat like a small amount of ghosting. (It was more obvious around one side of brighter pixels). Also the bandwidth of input signals on poor monitors had a somewhat low pass filter look to them.

    If they really want to get accurate, then they can also add a simulated Phosphor burn which was common on old arcade games (yes, thanks to this conversation, I'm feeling old today). Anyway, a small amount of phosphor burn would look very effective. :)

  30. Max

    @ Matt

    Also dont forget...skipping eating lunch at school and using your dollar to play a couple quick games.

  31. Anonymous Coward

    Bring back 8bit gaming

    Hmm, not sure I need this - especially if some nice kind soul out there can tell me either (a) where to get a replacement Vic20 RF modulator; or (b) where to get selfsame RF modulator repaired.

    I just want to be able to prove to my smartarse kids that yes dad _did_ used to have to wait 5-10 minutes to play a crappy video game that looks worse than the ones el cheapo multigame boxes you can get out of the thrift stores.

    That said, I've also got an old A1500 Amiga I'd like to resuscitate (quick game of Sidewinder would be cool).

    Re: Graphic Improvements (by Dennis) - sorry I think you'll find that "Kalecovision" you're remembering was actually a "Colecovision" - see

    Quick word to Jeff Minter - please, please, please release the old lightsynth's for PC's etc. Yes, I know there's that one in the Xbox360, but it's not the same as pulling of some real rope-smoking show using the keyboard.

    Anyone got a pill to cure nostalgia? ;-)


  32. Mike

    not right

    I still have my old 8-bit computer (a coco3 if you must know) and it doesn't look anything like the image shown. Granted, I'm using a commodore 1702 for the display.

  33. Another Anonymous Coward

    anti-aliasing, 80's style

    Interesting how the CRT image looks better due to the blurriness softening the edge of the pixels.

    Kind of amusing how modern games instead have to use a lot of computing power to achieve the same smooth edges as the fuzzy old monitor.

  34. fluffy

    A better CRT emulation

    One of the screen savers in the xscreensaver collection (which sadly I can't seem to find ever since updating to Ubuntu 9.04) does a VERY convincing job of looking like an older dysfunctional CRT. When I first saw it running on my laptop I had to do a major double-take, because it was absolutely spot-on.

  35. fluffy


    There it is. XAnalogTV does an extremely convincing job of looking like a crappy old CRT.

  36. Alex Taylor

    Re: Bring back 8-bit gaming

    Why not make/get a 5-pin DIN to 2x phono adapter for the Vic-20 and plug it into a TV's audio line-in and composite video inputs? That's what I did with mine (same adapter works on the C64 too), the picture's miles better than the Vic's RF modulator, which I found was never very good anyway.

  37. Darryl

    The ultimate feature...

    Does it simulate burn-in if you leave it running too long too?

  38. Ed


    By John "Never mind the colour bleed and bluriness, I've shown my 11yo son the games I used to play using a C64 emulator, and he thinks they are totally lame with awful graphics, and 'No thanks - I don't want to play'."

    I always find it funny that a game of less than 720k (the size old single sided floppys for you youngsters) could entertain you for hours or days (or weeks in some cases) yet with very very very little effort i can find a current release game of massive with more bling than 50c yet it holds my attentions for mere minutes......

    There is no substitute for substance

  39. FaberfoX
    Thumb Up

    A step in the right direction

    I hope they provide the source and would love to see this integrated with most emulators.

    It should allow tweaking of the parameters and come with presets for different types of TVs.

    Those kids that don't get of my lawn won't care much but I thank these guys (and emulator coders) for making my childhood dreams come true.

  40. BristolBachelor Gold badge

    Lightguns and reflections

    The most important difference is that using a CRT allows the use of a proper light-gun. You can't beat TimeCrisis (unless you work for the Metropolitan Police and head to your nearest tube station).

    As for reflections; my old CRTs have a lovely anti-reflection coating meaning I can sit in a bright room and work all day. The new LCD types; especially this laptop mean I have to sit in a dark room unless I want to use it as a mirror.

  41. Simon
    Thumb Down

    Can't emulate the low latency of CRT on a LCD

    I'm was an avid 8bit gamer, and one thing that has gotten worse and worse (and worse) since I were a lad is 'thumb to eye' latency, or, how long a button press on the controller takes to make a change to the image on the screen, and register in the old noggin.

    Lets take the 8bit SNES, connected to a CRT - its the best case, 'thumb to eye' was as low as 2ms (0.002 seconds) and at worse 18ms (PAL) or 14ms (NTSC) for a typical 2D game (VBLANK is 2.5ms).

    Connect a SNES to a LCD TV, and you now have the TV's frame buffer in your way, plus the delay to change the LCD image, and if you don't have a 'game mode' on the TV, a multi-field deinterlacer too.

    This adds 16~20ms to the delay, at a bare minimum, typically double that, and a good deinterlacer will add upto 40ms, enough to need the TV to buffer and delay the audio so it does not go out of sync.

    Ignore the '5ms latency' claims of the manufacturers, they only measure grey to grey, black to white, even on a modern set, is still around 30~40ms.

    Now go to 3D, at 30 fps, and due to 3D being renderd to a back buffer, you can add another 30~40ms to the pipe, sometimes another 30~40ms if the game buffers its graphics commands for a frame.

    Put it all together, and delays of over a 10th of a second (100ms) are not uncommon in modern video games, on modern display hardware.

    So, if you ever wondered why the good old games 'felt' better, IMHO, this is why.

    Plasma, and OLED offer the best hope for this, but unless the 'Game Mode' on those TV's emulates the immediate display of the image signal, that was inherent in CRT we will never get back the to twitch gaming of yesteryear.

  42. Anonymous Coward
    Anonymous Coward


    My large widescreen Sony CRT based television is still going strong and I've calculated I've had it nearly 11 years. And no sign of it packing up. LCD's eat your heart out.

    F**k knows how I'm gonna get it out of my flat when it does finally die! It's that big and heavy.

  43. Dillon Pyron

    Re: CRT

    How to get it out of the flat? What floor are you on? Make a game of it. Take bets on how close you can get to the sunroof of your landlord's AMG.*

    *Game works best from 8th floor or higher, due to the effects of wind and the pleasant sound it makes when you hit the bullseye.

This topic is closed for new posts.

Biting the hand that feeds IT © 1998–2021