Gaussian Blur in GIMP 2.8

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1

For my own personal usage of GIMP, I am having a major problem with 2.8.

…However, it seems that it definitely seems as though this problem is unique to my own settings of GIMP 2.6, as everybody seems to insist that this given effect works identically for them in 2.8 as it did back in 2.6.

Be that as it may, this situation is very important for me because I use it all the time…and now I cannot achieve the effect in my GIMP 2.8! So this is very bad for me.

First, let me just show the effect:

The effect I’m describing was applied to the photo of Luke Skywalker, there.

The effect was also applied to this photo, as I needed to cut out the background behind my head, but I did not want the area around my head to then look all jagged and fake:


So, how were these smooth perimeters achieved for me in GIMP 2.6? I did this a billion times:

1) Make the Selection
2) Feather the Selection the desired amount
NOTE: The “marching ants” selection did not deform in any way at this stage. It 100% retained its structure when the Feathering was applied. Again, this was just for me in my GIMP 2.6.
3) Delete the Selection’s inverse.

That’s all. Then, you had a perfectly smooth, gradual transition between the foreground and the (now deleted) background. See the results in the Luke Skywalker picture and the little headshot.

But now…things behave radically different for me in GIMP 2.8. Most importantly: I cannot achieve this incredibly important effect! (I can go over edges with a fuzzy eraser, but this is both too time-consuming and very imprecise.)

What happens now? Well, in the first place, when I have a Selection, and then I go Feather > Selection, the “marching ants” deform into a smoothed out version of the Selection:

http://i1222.photobucket.com/albums/dd499/ComicsPlus3/FeatheringProblem.png
FeatheringProblem.png800×502 279 KB

Secondly, as shown above, when I then delete the Selection’s inverse, the actual gradient/blur applied is…much less effective. It doesn’t seem to actually blur, but rather it just fades out its Opacity:

http://i1222.photobucket.com/albums/dd499/ComicsPlus3/Temp-3.png

I started a thread about this at GimpForums. The first two replies indicated that, for these users, the behavior I describe from the Feathering in 2.8 was, for them, exactly the same as 2.6! So it seems that I somehow altered my settings in 2.6 and it behaved differently than for others.

Be that as it may…I personally really need my 2.8 to behave as described at the top, the same way it behaved in my own 2.6.

Does anybody know how I can now achieve the effect described above, as shown in the photo of Luke Skywalker and in my headshot?

Thanks as always.

2

I just downloaded 2.8 and installed over my 2.6. I tried this process and I had the correct behavior if all I am supposed to do is make a selection, feather and choose amount, and invert and delete a few times. It was the same as in photoshop and in my previous gimp.

I see in the tool box below that there is an option to create a ‘roundness’ to the selection, and by pulling the bar to the right I can reproduce your rounded corner selection area.

3

Yes, thank you. This was established and stipulated already.

I’m trying to then find a way to achieve the described effects now in GIMP 2.8. For me in my 2.6, it did this through Feathering - though obviously something in my program was different than the norm.

Can you please get a screencap of what you’re talking about?

And note that I do NOT want a rounding of the Selection (the marching ants) when I apply the Feathering.

4

I’m trying to upload a picture. It seems that Gimp remembers your tool settings each time you last use it, so if somehow you have the rounded corners ticked, it will apply the setting the next time you make your selection. When using the rectangle selection tool, that was when I noticed the dialog available in the tool bar below.

Heck, I can’t get the pic to upload. I’ll see after I get up in the morning.

5

Okay. I don’t see this, but I’ll wait for your screencap. Thanks.

6

https://www.facebook.com/media/set/?set=a.168370716588379.41243.109266389165479&type=1#!/photo.php?fbid=289633944462055&set=a.168370716588379.41243.109266389165479&type=1&theater

Messy, but its on my facebook page so you can see it there.

7

Oh, I see. Thank you for the effort, but that is a different thing. I was discussing what the Feather effect does to the Selection.

8

Here is another little graphic I made in an attempt to solve this problem - this is a colossal obstacle for me and my GIMP usage. I’ll be incredibly grateful for a solution.

Batman-1.jpg366×1001 156 KB

9

In my experience, the better and more accurate the selection, the less you need worry about how the edges will look. In both Gimp and Photoshop, I stay clear of the fuzzy selection/ magic wand and either use the polygon selection tool with many deliberate edges to build a very close cut, or I lean on the pen tool to draw a path around my object to get a clean selection. I know, it takes time and is labor intensive at times, but this is the best way. The Photoshop erasers for background erase and magic erase work, but not as well as you might think - I play a lot of games with copies on layers adjusted for intense level changes to see better and force the erasers to pick what I want. I then make the selection from the ‘erased’ layer and attribute it to the original image layer with the original levels…

I am not a heavy Gimp user, but I try to use it when I can to keep grounded in the program.

10

I use layer masks myself. It’s easier to tweak things. Video Demo:

Here is your Luke example done with a layer mask. XCF file here so you can mess with it.

LukeCutout.png851×505 396 KB

11

Also, forgot to add after looking for videos. :stuck_out_tongue:

The most likely reason for your feathering issue is you’re trying to use it on lower res images than you have in the past. GIMP and Photoshop both round off when you feather (it’s just a math issue). When you’re on a decent resolution image, you’re less likely to notice it rounding because it has more pixel density to work with. 10 pixels on a 4000px image is pretty small, on a 500px wide image, 10 pixels is pretty noticeable. That make sense?

So if you tried to cut out this Luke for example, I imagine your normal workflow would work more closely to how you expect.

I’d still recommend Layer Masks, because you can go back in and tweak the cut with the paintbrush, blur tools, dodge/burn or use blur filters on it. Feathered selections even work with it.

12

Double post

13

I understand that it’s best to work with high-res images (I think everybody does) and how one pixel is relatively less distance in an HD image than a low-res image.

Do you know of a place where I can request a script or add-on for this? I know almost precisely what must be achieved:

  1. Selection (with ZERO deformation of it)
  2. A designated distance from the pixels is
    a. progressively blurred and/or
    b. progressively made transparent

So if you have a square and you apply this to a Selection, then the square’s perimeter then has a beautifully smooth transition from it to the (now deleted) Selection area.

Bizarrely, this is now my Feathering worked in 2.6. I used it at least a thousand times - very often for cut-outs that I would then place in Blender to give them nice transparent edges. I’ve tried everything to replicate this (including re-installing 2.6 to duplicate the old success, but that failed) but it’s obviously just gone. This is beyond frustrating for me, personally, since I used it so much.

14

I’m not sure where you’d go to get a script like that. Best suggestion I can give is to increment your feathers

Edit: Screwed up - retry

  • Select without feathered
  • Select -> Feather - 10pixels
  • Delete x number of times

It still rounds it so I doubt it’s what you want either.


15

Thanks, XRG. I just attempted the progressive feathering technique and, although I couldn’t really notice a difference, I will keep it in mind for future use, if times are tough (if I can’t resolve this!)

I requested such a script/add-on (I don’t really know the difference) at my thread on this problem here at GIMPForums.com (although those boards are really not very active).

Thanks for your interest and time.

16

Whoa, thanks for the screencaps there, XRG! Those are pretty compelling! (It’s funny that I really couldn’t notice much - but, then, I was just kind of eyeballing the marching ants, rather than doing a direct and conclusive comparison like you.)

Thanks…now I’ll DEFINITELY keep your tip in my back pocket!

17

If anybody has the skills, I would personally be hugely, hugely grateful for any sort of script/add-on which would allow users to achieve the Feathering effect without the distortion of the Selection shape. I believe that giving user’s the option would be tremendously popular for everybody, and definitely with me! (For instance, just having a checkbox in the Feathering dialogue that reads, “Distort Selection”, and then the user could opt for either one, that’d be perfect.)

I have a thread on this at the GIMP forums here.

This is tremendously important to my personal GIMP usage, and so, again, I’d just be thankful beyond words.