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 Post subject: Scanline issues!
PostPosted: Mon Jul 09, 2018 7:19 pm 



Joined: 06 Oct 2015
Posts: 11
I've searched for a answer or even the question being asked but to no avail.
The issue being with scanlines loosing definition with vertical scrolling games or just any vertical up or down motion of sprites etc
eg Elemental Master
Do anyone else get this!
I'm playing all my retro through an ossc to a benq gaming monitor HDMI. picture looks great still or horizontal scrolling just the vertical movement looses the lines slightly, eg Ghouls and ghosts jumping!

I've an slg 3000 which I'm going to try with the dreamcast direct vga but cant find were i've put it so might have to wait for my toro to arrive!


Thanks

Mike


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 Post subject: Re: Scanline issues!
PostPosted: Mon Jul 09, 2018 7:38 pm 


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Location: Germany
it's normal. Doesn't matter if you're using a CRT or LCD.

I'm pretty sure it's an eye coordination thing, but I'd still like a proper explanantion for the effect.


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 Post subject: Re: Scanline issues!
PostPosted: Mon Jul 09, 2018 7:43 pm 



Joined: 06 Oct 2015
Posts: 11
you could be right because has your eyes move round the screen some bits appear sharp,

I thought it could be a issue with the response rate of the monitor but im sure its max 3ms


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 Post subject: Re: Scanline issues!
PostPosted: Mon Jul 09, 2018 8:16 pm 


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Joined: 05 Nov 2013
Posts: 6324
Location: Craig's
As they say it's normal, but motion perception on most LCDs isn't nearly as good as on CRTs for several reasons, so they make it harder.

If you increase the multiple on the OSSC (x4 or x5 assuming your monitor can handle these) you will gain more sharpness, which in practice improves motion clarity a bit.

You might also want to check if your monitor's overdrive is on, iirc it's called 'AMA' on BenQ monitors. This is used to increase the LCD's response times.
Typically the middle setting is balanced and recommended, and the faster one is a bit too much (it'll be snappier but you might see some color sticking artifacts or dark ghost afterimages)

It would also help to use rather high hybrid scanlines strenght settings, so the fake lines aren't too prominent on the bright parts of the picture and don't get too much in the way.

In any case don't expect too much, playing with simulated scanlines over an LCD can only bring this much realism.

Personally there's a lot of games for which I leave the scanlines off and simply set a lower multiple mode (2x or 3x), sometimes mixed with a hint of reduced sharpness from my monitor's settings. And well once you find a good balance it can look good-enough like this and be more comfortable for playing.



PS: ways to improve scanlines imitation on a flat panel include higher refresh rate panels and use of emulation, or interpolation (tv soap opera effect), or strobing, OLED (for its instant-pixel-response) etc, but no solution money can buy at the moment is considered perfect yet.
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 Post subject: Re: Scanline issues!
PostPosted: Tue Jul 10, 2018 8:03 pm 



Joined: 06 Oct 2015
Posts: 11
Thanks for the reply. Much apricated.

When you think your nearly at perfection another hurdle gets in the way haha

Suppose its all part of the fun .

Mike


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 Post subject: Re: Scanline issues!
PostPosted: Tue Jul 10, 2018 10:02 pm 



Joined: 12 Sep 2012
Posts: 145
Fudoh wrote:
it's normal. Doesn't matter if you're using a CRT or LCD.

I'm pretty sure it's an eye coordination thing, but I'd still like a proper explanantion for the effect.


Isn't it just a side effect of the retina persistence of vision ?


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 Post subject: Re: Scanline issues!
PostPosted: Tue Jul 10, 2018 10:24 pm 


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Location: Germany
maybe. It's still a weird effect though. Sometimes you can manage to follow a sprite with your eyes while it's crossing scanlines and it will retain it's scanlined look.

Also, technically, always the same horizontal lines stay dark. And since sprites don't move in half-pixel steps, but only a full pixel / line at a time, it's also always the same lines within a sprite that stay dark. Still when crossing any scanlines it looks as if it's being displayed interlaced instead of progressive.

I would guess that this is one reason why in the arcades the monitor orientation was choosen to match the scrolling direction.


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 Post subject: Re: Scanline issues!
PostPosted: Tue Jul 10, 2018 11:04 pm 



Joined: 12 Sep 2012
Posts: 145
For me it's the same optical illusion than these :

https://www.testufo.com/persistence
https://www.testufo.com/eyetracking


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 Post subject: Re: Scanline issues!
PostPosted: Wed Jul 11, 2018 2:19 am 


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Joined: 09 Aug 2017
Posts: 1119
Location: Australia
Try eating something crunchy and watch your screen at the same time it always catches me off guard.


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 Post subject: Re: Scanline issues!
PostPosted: Wed Jul 11, 2018 7:29 am 


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Joined: 17 Nov 2016
Posts: 229
Location: Italy
Fudoh wrote:
it's normal. Doesn't matter if you're using a CRT or LCD.

I'm pretty sure it's an eye coordination thing, but I'd still like a proper explanantion for the effect.

Yeah, it also seems to depend on scrolling speed. With a Mega Drive you can do alot of interesting tests.
Raiden Densetsu is pretty slow, and I can properly recognize scanlines during gameplay. On the other hand, I can't with Musha Aleste, even though - when I just focus on the main sprite during attract mode and follow it - they suddenly become apparent all around it. Finally, during the intro of Gunstar Heroes, there's a scene with buildings scrolling vertically so fast, scanlines become fully visible again.

Syntax wrote:
Try eating something crunchy and watch your screen at the same time it always catches me off guard.

Haha, this too. :)


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 Post subject: Re: Scanline issues!
PostPosted: Mon Dec 24, 2018 10:02 am 



Joined: 04 Aug 2010
Posts: 880
Location: Adelaide, South Australia
Galdelico wrote:
Yeah, it also seems to depend on scrolling speed. With a Mega Drive you can do alot of interesting tests.
Raiden Densetsu is pretty slow, and I can properly recognize scanlines during gameplay. On the other hand, I can't with Musha Aleste, even though - when I just focus on the main sprite during attract mode and follow it - they suddenly become apparent all around it. Finally, during the intro of Gunstar Heroes, there's a scene with buildings scrolling vertically so fast, scanlines become fully visible again.


I noticed this with Raiden as well, no other vert shooters I have on the console show scanlines as they 'should'. Another interesting one is the flying aircraft carrier on stage 2 of Vapor Trail - it scrolls up slowly enough from the bottom of the screen that the lines are clearly visible, juxtaposed against the rapidly scrolling background underneath, where of course they are missing in action :)

I'm kind of annoyed that my Sony X900F w/Framemeister doesn't handle this properly. The BFI doesn't help since it only flickers at 120hz. If it's caused by 60 fps persistence, maybe I should have looked at one of those LG OLEDs instead, where I understand persistence is not an issue. But then I'm not sure that's the only issue. As an aside I'll say for the record my Samsung Plasma from 2009 didn't exhibit this issue, although because it lacked a full pixel/1:1 mode the scanlines were messed up anyway (which was sort of the reason I thought it was time to upgrade my panel). What's funny is a couple of Panasonic Vieras I've played around with DID have the issue of vanishing scanlines in vertical scrolling games, so IDK what's going on there.

After scouring the forums I haven't seen much discussion about this topic, but what there is seems to point to the cause(s) being at least one of, or a combination of the following:

-LCD motion persistence

-Use of sample and hold

-Pixel response time

-Refresh rate of display mismatched to source fps ?

-Optical illusion related to eye tracking

Does this phenomenom occur with OLED panels like the LG C7/C8? Is it just something people have learned to live with or did I buy the wrong panel for 60 hz gaming?
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 Post subject: Re: Scanline issues!
PostPosted: Mon Dec 24, 2018 11:08 am 


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Joined: 06 Mar 2006
Posts: 11496
Location: Germany
It's the use of sample and hold. You'll have the same effect on a current consumer OLED (e.g. from LG), but then again I would like to remind you to watch the effect on a CRT once again. It's very similar to what you see on a modern OLED. By no means does your average CRT retain fully visible scanlines. An OLED with rolling scan on the other hand retains scanlines quite nicely when scrolling lateral to the scanline orientation.


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 Post subject: Re: Scanline issues!
PostPosted: Mon Dec 24, 2018 11:50 am 



Joined: 04 Aug 2010
Posts: 880
Location: Adelaide, South Australia
Thanks for the response. Looks like I'll be satisfied until better technology arrives in the consumer space then (if ever).
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 Post subject: Re: Scanline issues!
PostPosted: Mon Dec 24, 2018 7:28 pm 



Joined: 14 Aug 2017
Posts: 142
THE EQUIN0X wrote:
Thanks for the reply. Much apricated.

When you think your nearly at perfection another hurdle gets in the way haha

Suppose its all part of the fun .

Mike


The last step in our rabbit hole is to get cyber eyes (or maybe some type of glasses) to get improve our shitty human vision and its motion persistence effect.

Basically we want to become like eagles and be able to see the spinning blades of a helicopter individually rather than as a blurry circle.


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