Comments on: Episode 038: A Phython in a Barrel

By: David gowers

David gowers — Tue, 22 Apr 2008 14:30:23 +0000

typically Python will coerce FLOAT INT, so in most cases that is a non-issue.
You should split up that call over several lines so it is easier to read, and comment it too. like this:

pdb.plug_in_map_object (img,layer_ovoid,
# mapt vpx vpy vpz
1, 1, 1, 2,
# posx posy posz 1staxisx 1staxisy 1staxisz
1, 1, 1, 1, 0, 0,
# .. and so on..

(spacing in the above may be incorrect)

By: Rolf

Rolf — Tue, 22 Apr 2008 06:37:18 +0000

Have you checked which parameter is INT and which FLOAT?

Gimp Users would be the right list, I think.

By: Bob

Bob — Tue, 22 Apr 2008 05:29:34 +0000

I tried putting .0 on the ends of the integers and still no dice. I was hoping if the issue was float vs. integer that python would autoconvert the integers to floats. Either way this function is really starting to cause me pain. Should I post on Gimp Users or Gimp Developers?

Thanks for the response, I have a hard time imagining how I could keep up with a site like this.

By: Rolf

Rolf — Mon, 21 Apr 2008 10:52:44 +0000

I haven’t checked my answer against facts - so this is a wild guess. No GIMP on this machine.

You have lots of integers (1 2 3) in your parameters. Perhaps some of them are floating point numbers. In this case you would have to write 1.0 instead of 1.

By: Bob

Bob — Mon, 21 Apr 2008 07:44:53 +0000

I created my first python test case and I can’t get through a “wrong parameter type” bug. Here’s the interesting part of my code:

img.disable_undo()

layer_ovoid = drw.copy(True) #make layer copy
layer_ovoid.mode = NORMAL_MODE
layer_ovoid.name = “Ovoid”

img.add_layer(layer_ovoid, -1)

pdb.plug_in_map_object( img,layer_ovoid,1,1,1,2,1,1,1,1,0,0,0,1,0,0,0,5,1,(255,255,255),-1,-1,2,-1,-1,1,1,1,1,0,27,True,False,False,True,1,0,0,0,0,-1,-1,-1,-1,-1,-1,-1,-1 )

img.enable_undo()
gimp.displays_flush

By: Nick

Nick — Wed, 02 Apr 2008 12:26:51 +0000

Great Rolf! As a Python programmer myself, I have wanted to try this out, but being a Windows user I had never managed it. With the useful links you have provided I hope to be able to get it up and running. I hope to see more tutorials like this in the future.

By: Raymond

Raymond — Tue, 01 Apr 2008 10:36:43 +0000

Excellent tutorial. I find programming tough, your tutorial is very helpful.

Cheers.

By: Warren

Warren — Thu, 27 Mar 2008 19:47:33 +0000

Reply to Steve:

Good tutorial. I know you are not using windows but the link below describes some of the troubles real people had installing Python into GIMP ( if that is the correct terminology.) I think you described the easy part of using Python in GIMP once installed. The hard part appears to be installing the software. Anyway thanks and maybe a simple script-fu tut. might be more useful since it already appears to be in GIMP.

http://www.gimptalk.com/forum/topic/Python-And-Gimp-2-4-25587-1.html

By: steven

steven — Thu, 27 Mar 2008 19:32:18 +0000

Simple question: How do I install Python under WinXP? I’ve followed the instructions founf here:
http://www.gimpusers.de/news/2007-10-24/gimp-2-4-tarball-erschienen.html
But when I install Gimp (Ver 2.4.5) the option for the Python extension is greyed out, nothing to choose Any idea anybody?
(Background: I’d like to try out this pythonfu-skript: http://www.gimptalk.com/forum/topic/python-fu-Dragan-effect-29852-1.html , may be the results are pure “kitsch”, let’s see.)

By: jaims

jaims — Thu, 27 Mar 2008 15:14:02 +0000

Nice article, once again

Btw, I’m a programmer too (I’m focused on ms .net stuff, not for preferences but for my job’s characteristics, but I’ve learned some python along the way).

The article is fine -among other things- because gets you to typing code in a smooth way, as you don’t have to be afraid of what programming is.

Saludos

By: Norman

Norman — Thu, 27 Mar 2008 13:48:23 +0000

I have been thinking about a comment Rolf made when replying to an earlier question of mine when he wrote that perspective distortion is not caused by the lens that is used. This surely is an over simplistic point of view. For example, a wide angle lens will give perspective distortion and what about a fisheye lens? I agree, that not having the camera level will accentuate the effect but there are examples where the same subject photographed near to with a wide angle lens shows distortion whereas photographed further away there is no distortion with a telephoto lens.

By: Meet the GIMP « Ang Pilipino GIMP

Meet the GIMP « Ang Pilipino GIMP — Thu, 27 Mar 2008 10:31:33 +0000

[...] Episode 038: A Phython in a Barrel [...]

By: Eric

Eric — Wed, 26 Mar 2008 15:42:58 +0000

OK just checking

By: Rolf

Rolf — Wed, 26 Mar 2008 14:03:07 +0000

@Eric: I know that, but this is a typical case of “too much information”. So I kept it low.

@Joseph & Serge: I’ll look if there are such collections except the gimp.org repository. I think it would not be prudent to clutter that with such one-liners. But if something turns out to be good it should be put there additional.

If I don’t find anything suitable I’ll set up a separate Blog at plugins.meetthegimp.org with a possibility to write articles for all.

By: Eric

Eric — Wed, 26 Mar 2008 11:55:59 +0000

Just a quick note, that #! on the very 1st line is no comment, it is a “shebang”, a special script direction to the interpreter unlike the usual # comments.

http://en.wikipedia.org/wiki/Shebang_(Unix)

Luv the show, Enjoy!!

By: Serge Gielkens

Serge Gielkens — Wed, 26 Mar 2008 10:30:23 +0000

A totally different show, let’s say GIMPro. I enjoyed it. This was my first introduction to Python and indeed, the way you showed it makes it look like a piece of cake.

As Joseph said, maybe a Meet the GIMP! plugin repository would be helpful.

As far as I am concerned I do not mind these more technical approaches to GIMP. But okay, I am biased: I am a programmer.

By: Joseph

Joseph — Wed, 26 Mar 2008 09:40:44 +0000

Brilliant introduction to programming (I am a programmer by trade)! I thought it was a stroke of genius to show a simple command with “an open mind” and not worry about all the other details. I think you may have whet many appetites to programming. Maybe you should mention some sites where you can download other peoples’ plugins and share your own creations as well as get help (the community is very helpful)?

By: Norman

Norman — Wed, 26 Mar 2008 09:04:47 +0000

That’s OK, what I wrote was with a little bit of tongue in cheek.

By: Rolf

Rolf — Tue, 25 Mar 2008 20:27:07 +0000

Downloadpage is updated, thanks for the hint.

Perspective correction is not part of the lens correction. It doesn’t depend from the lens you use but from the angle between film/sensor plane and your subject. If you tilt it, you get these distortions. A correction is shown in the last show with the high rises at the Potsdammer Platz.

By: Roberto Ballerini

Roberto Ballerini — Tue, 25 Mar 2008 19:41:24 +0000

You haven’t updated the download page (even if the zip file is available)

By: Norman

Norman — Tue, 25 Mar 2008 19:26:58 +0000

The Python programming is interesting but rather over my head. I have tried to get to grips with Python but failed. Correction of lens distortion is covered as far as barrel distortion is concerned and next, what about perspective distortion. I think I know how to do it but confirmation by a demo from you could be helpful. I have several slide copies which show mild to quite severe perspective distortion because, at that time, I used a 28mm lens.