How do you make a filter affect more than just the boundaries of a PNG?

[NightShadow28]

I am trying to add a filter to a transparent PNG but the filter (brush strokes) is constrained to only affect the inner parts of the PNG and not cross the boundaries.

PNG without filter

PNG with filter

I merged the PNG with the blue background (with spreads across the entire artboard) to see if that would allow the filter to affect the edges of the PNG, and it worked! (It might be a little hard to tell but the edges in this bottom picture expanded beyond the boundary, so the edges have more strokes)

The only problem is that I want the PNG to be separate from the background.

Any idea on how I can go about having the filter affect more than just the inner parts of the PNG?

[Bojan Živković]

The answer seems to be that the filter requires details to produce the effect. 

[c.pfaffenbichler]

Which exact Filter are you talking about? Please post screenshots. 

Could you please post screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible? 

[NightShadow28]

Filter:

100% view

[c.pfaffenbichler]

Can you provide the png of (part of) that element? 

[c.pfaffenbichler]

[D Fosse]

Seems simple enough: copy merged/paste, run filter on this new merged layer, crop layer back to original size (ctrl-click the original layer to get selection).

[NightShadow28]

Yes, that does work, however, the selection isn't going to be the cleanest. It's going to be a hassle to clean up the edges.
Thank you for your answer.

[c.pfaffenbichler]

Some Filters disregard Transparency; as a Work-around one can split RGB-content and Transparency and apply the Filter to both.