[MadVR] "Image Doubling" vs. "Chroma Upsaling"

[paulescobar]

I've been testing the standard 720p videos I watch, and have determined the maximum settings my system can handle without tempting dropped frames.

I see two different routes available to me:
1) Have "Image Doubling" enabled, at the cost of "Chroma Upscaling".
2) Have "Image Doubling" disabled, with a gain in "Chroma Upscaling".

So as an example, let's express these routes as actual settings:
1) Image Doubling (always Double Luma 64, always Quadruple Luma 64). Chroma Upscaling (NNEDI3 16). Image Upscaling (Jinc 4).
2) Image Doubling (NONE), Chroma Upscaling (NNEDI3 128). Image Upscaling (Jinc 4).

In the example, the key difference is Chroma Upscaling of 128 (without "Image Doubling") vs. 16 (with "Image Doubling").

My question is, which route does more work to increase video image quality?

[huhn]

that that looks best to your eyes.

using always is pretty much worthless.
let's give you an example you have 1080p screen and your source is 1000p now nnedi 3 is used to scale it to 2000p just to be downscaled to 1080p again by your downscaler. it very hard to believe that nnedi3 will have a positive effect in this case.

chroma scaling is usually very unimportant compared to luma scaling.
not sure why someone would use jinc 4 but do as you pleases.

[paulescobar]

that that looks best to your eyes.

using always is pretty much worthless.
let's give you an example you have 1080p screen and your source is 1000p now nnedi 3 is used to scale it to 2000p just to be downscaled to 1080p again by your downscaler. it very hard to believe that nnedi3 will have a positive effect in this case.

chroma scaling is usually very unimportant compared to luma scaling.
not sure why someone would use jinc 4 but do as you pleases.

Interesting. I was testing last night, and both routes showed some improvement over my typical "Chroma Upscaling: Lanczos 8, Image Upscaling: Lanczos 8" setting.

Though between the two routes, it was too subtle to differentiate. So I was hoping there was some technical factor that could set the two routes apart.

...

Actually, Jinc 4 was just randomly inserted into my example because it happens to be the highest Jinc possible in either of those two routes.
When "Image Doubling" is enabled as previously described..."Image Upscaling" of Jinc 8 causes frame drops.
When "Image Doubling" is disabled, and "Chroma Upscaling" is increased to 128..."Image Upscaling" of Jinc 8 also causes frame drops.

In my actual usage..."Image Upscaling" is typically set to Jinc 3, Lanczos 8, or Soft 70-100 (depending on what type of video I am loading).

...

Thank you for that interesting explanation of "Image Doubling". Other explanations I read elsewhere are vague and do not really explain what it does...or under what conditions it can improve image quality.

Can ask you two follow-up questions?

1) You imply that "Image Doubling" involves downscaling (I have read it elsewhere as well).

Does that mean the setting for "Image Downscaling" is used...when "Image Doubling" section is enabled?

For example, I have "Image Downscaling" set to "Cutmull-Rom, Anti-Ringing, Scale in Linear Light".

Does this sound okay to you?

2) Also, under what circumstances do you think "Image Doubling" section should be enabled?

[huhn]

Interesting. I was testing last night, and both routes showed some improvement over my typical "Chroma Upscaling: Lanczos 8, Image Upscaling: Lanczos 8" setting.
lanczos 8 is a pretty bad resizer tons of aliasing and ringing. try lanczos 3 AR high is simply not better for this type of resizer.

Actually, Jinc 4 was just randomly inserted into my example because it happens to be the highest Jinc possible in either of those two routes. Jinc 8 causes frame drops.
and jinc 8 is a bad resizer. yet again higher is not better.

1) You imply that "Image Doubling" involves downscaling (I have read it elsewhere as well).
nnedi3 can your resize by the power of 2 (that's why it's called image doubling). so if it is used on a 720p source is always scales to 1440.
nnedi3 was a line double deinterlacer in the frist place.

Does that mean the setting for "Image Downscaling" is used...when "Image Doubling" section is enabled?
if you scale over your target resolution yes.

For example, I have "Image Downscaling" set to "Cutmull-Rom, Anti-Ringing, Scale in Linear Light".

Does this sound okay to you?
it's offend used and i use it my self.

2) Also, under what circumstances do you think "Image Doubling" section should be enabled?
for a 1080p screen
i personally only use it for x2 scaling so source up to 540p. a lot of people use it for 720p toothat would be x1.5.

and don't forget these are my opinions maybe someone found a good use for jinc 8 but i doubt it.

[Anime Viewer]

I've been testing the standard 720p videos I watch, and have determined the maximum settings my system can handle without tempting dropped frames.

I see two different routes available to me:
1) Have "Image Doubling" enabled, at the cost of "Chroma Upscaling".
2) Have "Image Doubling" disabled, with a gain in "Chroma Upscaling".

So as an example, let's express these routes as actual settings:
1) Image Doubling (always Double Luma 64, always Quadruple Luma 64). Chroma Upscaling (NNEDI3 16). Image Upscaling (Jinc 4).
2) Image Doubling (NONE), Chroma Upscaling (NNEDI3 128). Image Upscaling (Jinc 4).

In the example, the key difference is Chroma Upscaling of 128 (without "Image Doubling") vs. 16 (with "Image Doubling").

My question is, which route does more work to increase video image quality?

Are you sure you're actually seeing a visual difference cranking the NNEDI3 numbers up so high? Many people (myself included) see no difference between the 16 neuron settings and any of the higher neuron settings. Likewise may users and madshi himself has said that using NNEDI3 for chroma is a waste of resources. Are you noticing a visual difference with quadrupling set? Most people don't.

I did some testing of NNEDI3 quite a while back when it was first used in madVR, and using NNEDI3 for chroma upscaling takes 4 times as long to render as Jinc with little to no difference in visual quality.

My recommendation is (if you're going to use NNEDI3) use it for image doubling, and use less taxing options for image and chroma upscaling. With the effect of image doubling on the image you probably will not see a significant difference between much of the image/chroma upscaling settings. Use less taxing scalers and you can put those saved resources to better effect with other features.

Here is the testing I previously did for reference:
http://forum.doom9.org/showpost.php?p=1687134&postcount=26933

[iSunrise]

Pretty simple, really.

Use NNEDI3 for image doubling (go as low as 16) always (use profiles) only if you are 720p or below and your screen resolution is at least 1080p and then use all of the remaining performance for chroma upscaling.

Luma should have a higher priority than chroma, but if you can use both at the very same neurons you are getting the most benefit for lower resolution content. You can only see benefits with some content and only when your source resolution and output resolution differs by a lot. Also, movies are not the best use-case where you can easily see the NNEDI3 benefits.

Use lower resolution content and zoom into the frame with your player and choose a scene where there's a lot of chroma information present (e.x. pink, blue, red) and you should be able to discern between different settings more easily.