It seems the Wii U has scaling issues that go far beyond what is commonly thought. It's not just the vWii mode that has problems: the same issues plague the 'native' system as well.
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The same issues are present in the vWii mode. Every body knows about the chroma shift issues, but the vertical blend is present there as well and can easily be seen by using the 240p Test Suite.
NOTE: These issues are present on the vWii in 480p WITH evWii enabled and set to 480/576p (this is the default and means that (vertical) scaling is disabled).
What I've found with the vWii is that for some reason, if you are unlucky, the red/green shift effect is exponentially worse, almost as if the effect is doubled. I.e. where there usually is a single pixel red or green, when it is in this 'mode' there is (at least) two pixel width red/green shift. If it is indeed doubled, it might simply be some bug where it passes some internal scaler twice. Though I don't have nearly enough knowledge of the system to say whether this is a possibility.
In any case, all of this means that the entire system likely has problems. There is no 'fixing the vWii mode', since the entire system is (somewhat) broken.
Hopefully, it also means that it might be easier to find a fix. vWii is not the culprit.
- First, the chroma shift or red shift. This is one of the major issues for the vWii mode that people want to get fixed. The issue presents itself as coloured pixels, often a green / red hue, on the edge between two solid colours.
However, the issue is also clearly present when in Wii U mode.
Below is a photo of Mario Kart 8. You can clearly see the problems around the "M" of Morton. On the left side, there is a green-ish pixel bar, whereas on the right there is a subtle red/magenta bar.
This is a Wii U running in 720p, set in System Settings.
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- Then there is vertical blending. This one is very subtle but I'm pretty sure the problem is real. Basically there seems to be a light blend between pixels on the Y-axis. This is visible through a 1px height transparent / blended line of pixels between two hard edges.
I've captured this on a photo below. Apologies for my lack of a capture device. What you can see is a transparent (or in-between) line between the white and the yellow edges of the square below. (The red shift is also clearly visible here).
While it might not seem like much, it means the entire image is most likely subtly blurred along the vertical axis, in addition to the horizontal axis (due to red shift, but possibly a similar blend is going on).
Full size image
The same issues are present in the vWii mode. Every body knows about the chroma shift issues, but the vertical blend is present there as well and can easily be seen by using the 240p Test Suite.
NOTE: These issues are present on the vWii in 480p WITH evWii enabled and set to 480/576p (this is the default and means that (vertical) scaling is disabled).
What I've found with the vWii is that for some reason, if you are unlucky, the red/green shift effect is exponentially worse, almost as if the effect is doubled. I.e. where there usually is a single pixel red or green, when it is in this 'mode' there is (at least) two pixel width red/green shift. If it is indeed doubled, it might simply be some bug where it passes some internal scaler twice. Though I don't have nearly enough knowledge of the system to say whether this is a possibility.
In any case, all of this means that the entire system likely has problems. There is no 'fixing the vWii mode', since the entire system is (somewhat) broken.
Hopefully, it also means that it might be easier to find a fix. vWii is not the culprit.
...but I don't think my eyes are lying here.The issues are present with or without OSSC Pro.
