Detailed workings of the selection "Refine" dialog

[EBC]

Hello all, I've read the documentation and watched the tutorial, but I'm still not clear on how these features are supposed to work.

In Photoshop, the Refine Edge Brush (which appears analogous to Affinity's Matte brush) adds to a total area which is the combination of everything that has been painted by Refine Edge Brush, plus whatever area is encompassed by the Radius. When you select "Show edge" in PS, it shows this combined area. And it appears this entire area is analyzed with the same algorithm.

In Affinity, adjusting the "border width" slider does not also show areas painted by the Matte brush. And there is no comparable "Show edge" checkbox.

So my questions are,

1. In Affinity, are the areas demarcated by "border width" indeed analyzed by the same algorithm as the areas that have been painted by the Matte brush?

2. If it is the same algorithm, is there any way to show the combined area being analyzed, similar to PS's "Show edge"?

And one question not directly related to the above:

3. When I paint with the "Foreground" and "Background" brushes, every stroke appears to result in a holistic re-analysis of the matted area. The changes are not confined to the area that I paint with these tools; changes happen even outside of it. In general this has good results. But if you want to make pixel by pixel changes, what is the best solution? I've been exiting the Refine dialog and using Quick Mask, but is there any way to accomplish this without exiting Refine?

Thanks a lot.

[Callum]

Hi EBC,

Sorry for the delayed response, I will answer your questions in the order they were asked  

1 As far as I'm aware we use the same algorithm a fellow staff member named Gabe goes into more detail with how this works in the below thread.

https://forum.affinity.serif.com/index.php?/topic/64011-difference-between-border-width-ramp/

2. Unfortunately, we don’t have a ’Show Edges’ option. Feel free to add this suggestion to the Feature Requests & Feedback sections.

3. One of our devs made a post regarding our Refine brushes that should make this all a bit clearer for you I will include a link to it below.

https://forum.affinity.serif.com/index.php?/topic/4962-refine-selection-can-you-manually-adjust-the-selection/&do=findComment&comment=20909

Thanks

Callum