Strategies for handling pixelation at centre of symmetric FX like kaleidoscope, polarkaleido, bendoscope

[webel]

Some out-of-the-box FX with circular symmetry like Kaleidoscope, Polarkaleido, Bendoscope etc by their very nature tend to create a noticeable pixelation due to stretching at the centre, so I'm looking for strategies to improve it. I have attached screenshots (stills) showing the typical challenge, it's worse in running video, you can sometimes see "streams" of pixel dots heading towards or out of the very centre.

I have Wire so I can encapsulate various recipes and strategies easily (although it does not yet offer every effect that Resolume does), and then use that standalone or as a custom video effect in a Resolume clip channel. I'm not VJing, I'm just creating content in small video exports, so I have a lot of control.

I've made some progress by using a small circular mask, applying blur to that, the using a video mixer to place it back over the original scene at the centre (see screenshot of basic Wire patch). It's better than nothing, but it's not optimal, and it tends to darken the area a bit, which is noticeable when you view the entire scene.

1st screenshot shows example of a pixelated "stretched" centre area.

2nd screenshot shows example of applying small blurred circle mask.

3rd screenshot shows screenshot of simple Wire patch.

Grateful for suggestions on other ways to try to address that central pixelation.

[EDIT: BTW this is a perfect example of why sub-patching is so desperately, urgently, needed in Wire, it should not be necessary to reproduce the solution in different patches (using copy and paste) or even duplicate the solution multiple times in one patch, it "should" be possible to encapsulate such strategies as a reusable sub-patch and just drag it in with its own encapsulated controls]

[webel]

Here's an attempt using PixelBlur instead of basic Blur with the same sized mask. I've made the screenshot of the result a little larger here so you can see it in context. I feel this is slightly better than using a central mask Blur, there is less obvious darkening.

[najork]

You could also sandwich the effect between two Resize nodes, enlarging and then shrinking, as a sort of forced oversampling. Not the most elegant thing, but maybe less resource intensive than a blur.

[webel]

Related: Wire: Add anti-aliasing/upscaling node

[webel]

@najork wrote:

> You could also sandwich the effect between two Resize nodes ...

Thx will try.

> ... maybe less resource intensive than a blur.

Performance not a big issue, I don't use it live, I either render from Wire or render from Clip view in Resolume (and on an M1 Max, 32GB).

[webel]

I'm having some success reducing distracting central pixelation with symmetric fx using the following simple strategy. The following sizes work for about 4K (I'm actually using 5K or 6K for reasons I won't go into here).

I create a mask with a small black circle about 50px diameter (and otherwise transparent background), and then I apply a Gaussian blur to it with radius about 25px, so the central pixel is (almost) still black. Then, in Resolume or Wire, I use this as an inverted alpha Mask.

The Mask can be applied before or after the symmetric effect, depending on the situation. For example, with the basic Kaleidoscope, it works well before it. I'm experimenting with the KPT Hippo Psychonaut, and apply the Mask afterwards. Similarly with Polarkaleido. I find having the subtle mask to black at the centre far better than central pixelation.

I actually found it difficult with Gaussian blur to keep the central pixel black enough whilst maintaining a pleasing radial blur. To create the masks I'm using Pixelmator, which has a blur kind called Disc blur, with that I found a blur radius of 35px worked well with a 50px radius black circle, and gave a smooth radial blur gradient whilst keeping the centre almost exactly black (enough for a quick test). It would be easy enough to make the centre (0,0,0) if needed. It might be possible to make the mask directly in Resolume too.

It takes a bit of fiddling to get the right circle and right blur settings for a given composition, but the result is good.

The attachments show closeups of the centre of a Polarkaleido scene without and with a small Gaussian circle alpha mask. The central pixelation is more prominent and distracting when there is movement than in these stills, especially when there is streaming towards or from the very centre.

Closeup Polarkaleido no mask

Closeup Polarkaleido with mask