4K Scaling Woes

[strygo]

First, a bit of back information. I recently picked up a Raspberry Pi 3 and installed RetroPie while visiting family. They had a spare cheap Emerson LCD (LF320EM4-A). I read online that the display only supported 720p, so I configured the Raspberry Pi to use that resolution. That looked better than the default, but it was still blurry -- most noticeably in the command-line/menu resolutions. Upon further research, I discovered the display's native resolution is actually 1360x768. Once I configured that, the display was crystal clear down to the pixel.

Fast-forward to today: I am attempting to connect the device to my 4K display (Vizio P50-C1). I assumed that either 720p or 1080p would produce similarly clear results, however this hasn't been the case. It's not super blurry, but it also isn't as clear as I had been seeing with the other display. This either implies that the native resolution of the display is something different than advertised (3840 x 2160) or the upscaling to 4K is distorting the image.

My prior understanding was that 4K displays don't always upscale from 720p/1080p properly. I had assumed that I had gotten lucky with my display, but now I'm wondering whether the display has been doing an imperfect job all along. Anyone have any ideas or thoughts?

[bobrocks95]

It might be upscaling properly... For video content though. If you want text as sharp as possible I'm not surprised that upscaling from 1080p doesn't look as sharp as 1:1 mapping on the lower-res display.

Some Samsung and maybe other brands' 4K sets allow for a line-doubled 1080p scaling mode, but I forget what the option is called. I haven't heard about recent 4K sets having that option though.

[strygo]

Thanks. What you've described is what I have feared. Are you aware of any standalone devices that do vanilla line doubling/tripling vs. something fancier?

I'll see if I can track down the marketing term Samsung uses for the capability.

[bobrocks95]

I think people have recommended the HD Fury Linker for 1080p to 4K scaling before, but it's a bit expensive if you're just using it for the one purpose. I'm sure someone else can offer more suggestions, but 4K scaling is probably still pretty niche.

EDIT: Here's an old thread that may have some useful information in it http://shmups.system11.org/viewtopic.ph ... 35&start=0

[orange808]

Hi Def NES 1080p >> HDFury Linker >> 4k >> Vizio 2016 D series 4k

Spoiler

Spoiler

If you want 4k at 60Hz, there still aren't many affordable options. The Linker is very nice, but it's a niche device.

Linker only accepts 1080p for upscaling to 4k. Does not accept any other inputs besides 1080p. The Linker does not accept OSSC linex5 1080p or 1200p, so it cannot be paired directly with the OSSC. The Linker does work very well with every video processor I've used with it (including DVDO's) and with a PC. I don't own any Raspberry Pi machines to test with, but it should work.

Internal sampling is not 4:4:4 chroma, despite some very sketchy marketing claims from HDFury. I don't remember what it uses. I think it's 4:2:2. (Not a huge deal, but worth mentioning.)

The Linker doesn't add any significant latency; it's under a decile of a millisecond, so it's not worth mentioning.

I do notice the difference in handshake time when the Linker is in the chain. It's probably just under two seconds of black screen. Can be annoying.

[Wolf_]

1080p does not upscale 1:1 to 4k, 720p on the other hand does.

[Fudoh]

both do. Redo your math.

[Wolf_]

both do. Redo your math.

Nope

[Makinx]

4K is 1080p times 2. How is that not a 1:1 upscale.

[Fudoh]

That's really good thing about 4K (well at least the UHD resolution that's used as 4K on consumer sets). You have EXACTLY four times the pixel count of 1080p (2x2) and nine times the pixel count of 720p (3x3), so both theoretically scale perfectly fine.

[Xyga]

We don't care about the math anyway, the problem is that most sets on the market apply a very basic undefeatable interpolation that breaks the integers and therefore the ideal consistency and quality of both 720p and 1080p upscaled, the blur and artifacts go from unnoticeable to 'refund' level.
Sony do exceptionally well, some recent models like the X900E also offer non-interpolated perfect integer scaling at least for 1080p in some mode, I don't know for 720p and other higher or lower. With most other brands it is hit or miss.

edit: 4k pc monitors are even worse in that field

[FinalBaton]

Sony do exceptionally well, some recent models like the X900E also offer non-interpolated perfect integer scaling at least for 1080p in some mode, I don't know for 720p and other higher or lower.

I'm really curious to see how 720p is handled on that set in the mode you mentionned

[Xyga]

I don't know if it even does, the only thing the review mentions is the clean 1080p>4K@120Hz mode, which is probably the closest thing to a decent giant pc lcd monitor ever.

[FinalBaton]

yes we don't know for now

[Wolf_]

This is why you shouldn't post at 5am. He mentioned 720p (which I assume is the native output) and going from 720 to 1080 would be a 1.5x upscale followed by the upscale to 4k and result in pixel rounding so if you have the option of going from 720 to 1080 through a xrgb mini or something into a 4k display it would be better to stick to 720.

I was on a bit of a binder.

[strygo]

The other thread mentioned the iScan Micro as a possible solution to this. The documentation for the device is super sparse - it has a single 3-position switch with "off" seemingly not providing any 'enhancements'. However, all the reviews/videos I find talk about how it is performing its magic (or not performing it sufficiently well) - no one discusses whether "off" does what we're looking for. The good news is that this device is now super cheap - $35 on Monoprice.

In reading about their iScan Mini, it provides a bit more flexibility - there are 2 separate toggles: one for scaling (which has an "off" setting) and another for 'enhancements' (also has an "off" setting).

Like the OP of the other thread, I'm hoping for something that can scale both 720p (3X) and 1080p (2X) directly to 4K resolution. The Linker seems geared toward converting 1080p only to 4K and its price is a bit high, so I'm hoping to get confirmation or disproval on the iScan devices. Anyone have any experiences with these?

[Fudoh]

I have the Mini, but not the Micro. But without seeing your display in action it's almost impossible to predict wether the DVDOs are for or not. At the price for the Micro you should definitely try though.

[strygo]

I'll also add that part of my motivation in tracking this down is to determine whether my PC upscaling adventures have in fact been hobbled by the Vizio's imperfect upscaling. The Lumagen is definitely the best solution I've found for sending an analog PC signal to the display, but it's still not crystal clear. I'm hoping that a better 720p/1080p upscale might be the missing link to having a 'perfect' solution.

[orange808]

The other thread mentioned the iScan Micro as a possible solution to this. ... I'm hoping to get confirmation or disproval on the iScan devices. Anyone have any experiences with these?

I had one and saw ringing. Nasty ringing. I got rid of it. There's still some photos somewhere on the forum.

The enhancement feature doesn't do much of anything. Video people bought Darblets instead--because that machine actually makes a difference.

I hear some people have been able to reduce the sharpness of their displays (soften the output) to hide the micro ringing--and been very satisfied with the results. Maybe I have the sharpness too high on my displays. Then again, my iScan vp50pro looks fantastic and the vp50 had very minor ringing, so take from that what you will. I blame the micro.

Last I heard, the micro doesn't play nice with the OSSC x3, x4, and x5--but there have been firmware updates to the OSSC since I owned a micro. Maybe that got better.

I hated mine.

[strygo]

orange808: Doh, not the glowing review I was looking for. I assume you were testing with enhancements off? For the Darblet, I read that it didn't support 4K so I stopped digging deeper.

Fudoh: With enhancements off, does the Mini do what you expect it to? Obviously I can't know how it will be handled by my display, but if it at least operates how it is supposed to, that is a step in the right direction.

[orange808]

orange808: Doh, not the glowing review I was looking for. I assume you were testing with enhancements off? For the Darblet, I read that it didn't support 4K so I stopped digging deeper.

Fudoh: With enhancements off, does the Mini do what you expect it to? Obviously I can't know how it will be handled by my display, but if it at least operates how it is supposed to, that is a step in the right direction.

Yep. Tested the micro with enhancements on and off. No difference in lag and not much difference in the output.

What worries me is that you want sharpness and the micro needs you to soften your output. Fortunately, the micro is dirt cheap, so it might still be worth a peek.

The Darblet isn't useful for games, but some people swear by the Darblet for video. I think it can make a lovely actress look like Edward James Olmos. Yuk.
(Plenty of detail, I guess.)

[strygo]

The Vizio is definitely exhibiting ringing. Decreasing sharpness helped a bit. One thing I noticed that is a bit curious is that at the bottom of the display there is a thin region where pixels are being unused. Could the display actually be a bit bigger than 4K resolution? I will experiment but if anyone is aware of a slightly larger resolution, I can give that a try as a starting point.

[h1ghju1ce]

1080p does not upscale 1:1 to 4k, 720p on the other hand does.

https://en.wikipedia.org/wiki/4K_resolution

"There are three main 4K resolution standards:

UHD-1, or ultra-high-definition television (UHDTV), is the 4K standard for television and computer monitors.
UHD-1 is also called 2160p[4][5] as it has a resolution of 3840 × 2160 (16:9, or approximately a 1.78:1 aspect ratio),
which is twice the horizontal and vertical resolution of 1080p, or three times the horizontal and vertical resolution of 720p.[4]
UHD-1 is used in consumer television and other media, e.g. video games.

UW4K is the ultra-wide 4K standard, with a resolution of 3840 × 1600, and an aspect ratio of 12:5 (2.4:1, or 21.6:9)
This resolution is most commonly used on Ultra HD Blu-ray discs, and PC gaming monitors.

DCI 4K which has a resolution of 4096 × 2160 pixels (256:135, approximately a 1.9:1 aspect ratio).
This standard is only used in the film and video production industry.[6] The DCI 4K standard has twice the horizontal and vertical resolution of DCI 2K."


So:

1920 x 2 = 3840
1080 x 2 = 2160

1280 x 3 = 3840
720 x 3 = 2160


Fudoh is referring to UHD-1 - he is right

Wolf_ is referring to UW4k / DCI 4K = he is right




If integer upscaling 1080p content to a 4K DCI screen you'd have 128 pixel borders at the sides
If integer upscaling 1080p content to a UW4K screen you'd lose pixels 280 at the top and bottom

[Wolf_]

1080p does not upscale 1:1 to 4k, 720p on the other hand does.

https://en.wikipedia.org/wiki/4K_resolution

"There are three main 4K resolution standards:

UHD-1, or ultra-high-definition television (UHDTV), is the 4K standard for television and computer monitors.
UHD-1 is also called 2160p[4][5] as it has a resolution of 3840 × 2160 (16:9, or approximately a 1.78:1 aspect ratio),
which is twice the horizontal and vertical resolution of 1080p, or three times the horizontal and vertical resolution of 720p.[4]
UHD-1 is used in consumer television and other media, e.g. video games.

UW4K is the ultra-wide 4K standard, with a resolution of 3840 × 1600, and an aspect ratio of 12:5 (2.4:1, or 21.6:9)
This resolution is most commonly used on Ultra HD Blu-ray discs, and PC gaming monitors.

DCI 4K which has a resolution of 4096 × 2160 pixels (256:135, approximately a 1.9:1 aspect ratio).
This standard is only used in the film and video production industry.[6] The DCI 4K standard has twice the horizontal and vertical resolution of DCI 2K."


So:

1920 x 2 = 3840
1080 x 2 = 2160

1280 x 3 = 3840
720 x 3 = 2160


Fudoh is referring to UHD-1 - he is right

Wolf_ is referring to UW4k / DCI 4K = he is right




If integer upscaling 1080p content to a 4K DCI screen you'd have 128 pixel borders at the sides
If integer upscaling 1080p content to a UW4K screen you'd lose pixels 280 at the top and bottom

What I was talking about was 720p upscaled to 1080p so you could run it into a 4k tv. But yea Ultra wide works as well.

This is why you shouldn't post at 5am. He mentioned 720p (which I assume is the native output) and going from 720 to 1080 would be a 1.5x upscale followed by the upscale to 4k and result in pixel rounding so if you have the option of going from 720 to 1080 through a xrgb mini or something into a 4k display it would be better to stick to 720.

I was on a bit of a binder.

[strygo]

I've ordered an iScan Micro and should receive it tomorrow for further testing.

Fudoh: you mentioned you have an iScan Mini. When you force it to scale without enhancements, does it behave how we'd like? Or is your concern that even if the iScan behaves properly, the Vizio may still mess it up through further manipulation of the image?

[Fudoh]

DVDOs never really behave as we'd like them to do. They have a very sharp scaling engine, often unsuited for video game material and with a tendency to cause ringing and they reduce the chroma resolution by converting to 4:2:2 internally (on 4K60 even 4:2:0).

But this said, the results with HD source material look usually good if you keep the TV's sharpness setting down and they don't have any problem with even upscaling of complicated source material (eg scanlined material), so there's a good chance that even the Micro will outperform your TV's own scaling.

[strayan]

Personally I'd just by a TV that integer scales 1080p properly.

[Xyga]

if only it was that simple

[strygo]

I'm not opposed to tracking down a model that handles it better, but from what I can gather, there is no go-to manufacturer that offers this on all of their lines and there are also no good online resources documenting this either.

If I could find a 50-55" 4K UHD for < $1000 that handles scaling 720p/1080p, I'd definitely consider it.

[RGBSource]

Panasonic has had a "1080p pixel by 4pixels" setting on their 2160p TVs for quite a few years now. The 2017 EX600 series has low input lag (~18.6ms) too according to this review. Unfortunately, Panasonic doesn't sell their TVs in the US, but they do in Canada and Europe. Vizio and TCL are what we get in the US instead of Panasonic.

The best overall TV of 2017 I've tested is the LG 55" C7 OLED. When you label the HDMI input with the Laptop icon it enables PC mode for 4:4:4 color. Both 720p and 1080p output from the Analogue NT mini look really clean. Since the LG OLED panels have 4 sub-pixels (RGBW), the resulting presentation is influenced. The C7 is a massive improvement over the EF9500 in terms of upscaling for retro gaming.

CGB core on the NTM @1080p on the LG C7 OLED in PC mode: