Creating an accurate blurring effect

[arpeggiomax87]

So as you may have notice in some of my comics, I tried to experiment making a blurring background effect on specific panels.

The way this looks tells that it's working fine in it's effect.

Now the problem is this:

You can see how it bleeds into the rest of the background, poorly shaving off of the effect and making it see-through.
Is there an accurate way to achieve this effect with Paint Tool SAI, Krita or FireAlpaca? I don't know how to use FireAlpaca or Krita so yeah.

[NickRowler]

For some reason your blur isn't blurring the edge of the figure. Even tho the details are blurred, the edge is too sharp.

Something that might also be helpful is using a box blur (left) instead of a gaussian blur (right). Because you can retain more details of the character.

[arpeggiomax87]

When I say effect, I meant I use a custom brush that imitates a blur effect. What it acts like is a multi-bristle water effect. It also washes out the the colors of the painting making it look weirder and disheveled.

[Seaby]

It looks like you're having an opacity problem? Either select 'Preserve Opacity' or 'Protect Alpha' so that your blur doesn't affect anything outside of the layer you're working on.
Without applying it:

While applying it:

And over a background:

[NickRowler]

Even with the brush, the outline of the character is still too sharp. Do you have a way of softening up the edges?

He also looks a bit transparent, so I think it is also removing from the opacity.

[DokiDokiTsuna]

When I say effect, I meant I use a custom brush that imitates a blur effect. What it acts like is a multi-bristle water effect. It also washes out the the colors of the painting making it look weirder and disheveled.

So it looks like you kinda just took this brush, selected the figure, and went to town on it...?

That technique would work with the background, since it has a mandatory outline (the panel border) so you can't see where the blur effect stops prematurely.

But objects within the panel don't have that, so they need to be blurred all the way. Like other people have said, blur the edges; it's not gonna look right otherwise.

Maybe try using the effect without selecting the figure [see below]. If that's not possible, you'll probably have to find another technique.

[disqette]

unlock opacity. if the opacity of the layer is locked, the edges won't blur