Preserve Alpha on Minimum Blur

[dmstraker]

Minimum Blur, turn up Radius. Border of image becomes transparent. Click Preserve Alpha. No change.

Cheers!

[walt.farrell]

Perhaps helpful to note that this is with the Live Filter, not the normal filter (as that doesn't have a Protect Alpha option).

For me, there's a change when I select Preserve Alpha, but I'm not sure it's right. Without Protect Alpha the edges go transparent in some images. With Protect Alpha they go black.

In the non-live filter they just blur.

[Chris B]

I assume that when enabling Preserve Alpha, its job is to broaden the darker pixels where it meets transparency. So as we increase the Radius, the transparency begins to increase and to combat it, Preserve Alpha is darkening the pixels around it, to the point they become black.

It seems right to me but I am happy to check with the developers. I've just noticed that iOS uses the wording 'Protect alpha' but macOS and Windows use 'Preserve Alpha' so I'll feed that back too.