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Plugin request: Channel Blur (red, green, blue, alpha)


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Hello,

I'd like to have tool that applies blur to each color and alpha channel separately. Not sure if that is possible but worth to ask...

I am especially interested in alpha (transparency) blur which should be very useful in some image blending techniques. But why not include all color channels then.

Below is my sketch of possible UI, just to show the concept (I "borrowed" main part of this image from Illnab1024's Advanced Greyscale plugin UI).

Each slider changes amount of blur on it's dedicated (monochrome) color plane.

channel_blur.gif

Possible enhancements could include drop-down option box for blur type (gaussian / fast / etc), and maybe even color space options (RGBa / Lab / ?)

Thanks,

Tanel

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That does sound like a handy plugin...probably better asked in the "plugins" forum, though.

Plugins forum is for publishing only. This is the correct place to make this request.

As for the request, I can see how this would be useful, but for now your best bet is to duplicate your image into the number of channels (3 for RGB, 4 for RGBA, etc) and use an adjustment (Curves, Curves+, conditional Hue/Sat, etc...) to make each pic only one channel, then blur each one separetely.

xZYt6wl.png

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No, the plugin forum is for plugin publishing only. He made the right decision to post it here.

That may be a good idea. It would be nice to have it combined with my suggestion.

EDIT: Gah! pyrochild beat me!

EDIT2: Actually, it looks like he had the same idea with the alpha blur as well :shock:

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That may be a good idea. It would be nice to have it combined with my suggestion.

Sorry I missed your post about Advanced Gaussian Blur, although I searched before posting :oops:

Yes, my idea is almost the same, I should have shared it under your post.

As for the request, I can see how this would be useful,

What's your opinion, is it at least possible to build into a plugin?

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Do you REALLY need to blur all three color channels separatly? (That would be a pain.)

Or, can you live with an Alpha Gaussian Blur? (That would be a snap.)

Alpha Blur is actually enough for me and I see real use for that. Leave out color channels if that's painful :)

I just imagined the further possibilities...

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Well, I don't know if I did this right, but here ya go:

http://boltbait.googlepages.com/GaussianBlurChannel.dll

The UI looks like this:

    GaussianBlurChannelUI.jpg

One limitation that I haven't worked out yet... You can't blur onto a transparent pixel. I'm just not sure what to do in that case yet.

Let's just call this the "alpha" build. Mkay? ;)

Click to play:
j.pngs.pngd.pnga.pngp.png
Download: BoltBait's Plugin Pack | CodeLab | and how about a Computer Dominos Game

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You know, Tanel, if all you want to do is a Gaussian Blur of the Alpha channel and you can live with a radius limit of 1-10, just use the Feather Plugin and set the second slider to Shrink. That is exactly what it is doing.

When I have time, I'll put a little more thought into the plugin I posted above. (Heh. So far, I've only spent 15 minutes on it. That's why its a little rough.)

Click to play:
j.pngs.pngd.pnga.pngp.png
Download: BoltBait's Plugin Pack | CodeLab | and how about a Computer Dominos Game

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Well, I don't know if I did this right, but here ya go:

Wow, that was fast!

Thank you, it works well at first glance :)

One limitation that I haven't worked out yet... You can't blur onto a transparent pixel. I'm just not sure what to do in that case yet.

As a "dirty" workaround, maybe just replace alpha 0 with 0.01 or something in the code before blur calc? Or add 0.01 to everything...

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Well, I don't know if I did this right, but here ya go:

Wow, that was fast!

Thank you, it works well at first glance :)

One limitation that I haven't worked out yet... You can't blur onto a transparent pixel. I'm just not sure what to do in that case yet.

As a "dirty" workaround, maybe just replace alpha 0 with 0.01 or something in the code before blur calc? Or add 0.01 to everything...

No, the problem is not the alpha level, that calculates fine. The problem is when changing from alpha 0 to something else, the color of the pixel is undefined. I solved the problem in this plugin: http://paintdotnet.12.forumer.com/viewtopic.php?t=3285 by making the color of transparent pixels the secondary color. Maybe that would work here as well.

Click to play:
j.pngs.pngd.pnga.pngp.png
Download: BoltBait's Plugin Pack | CodeLab | and how about a Computer Dominos Game

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No, the problem is not the alpha level, that calculates fine. The problem is when changing from alpha 0 to something else, the color of the pixel is undefined. I solved the problem in this plugin: http://paintdotnet.12.forumer.com/viewtopic.php?t=3285 by making the color of transparent pixels the secondary color. Maybe that would work here as well.

Note that color information is still there, if transparency has been achieved with Eraser tool (or even with your Transparency plugin). I would like to keep this image information intact (not replaced with single color). So that if you reduce transparency for Erased or Transparency'ed pixels then the "hidden" picture becomes back visible. The new Gaussian Blur Channel plugin works like this now and I like it.

Maybe you could fix this also in the Transparency plugin: so that if you use Transparency twice - first turned selection fully transparent then in 2nd run turn back to opaque, you would finsh up with the original picture. The "really empty" pixels in PdN are actually white, are'nt they (R=255, G=255, B=255, Alpha=0). So just treat those as white?

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