Episode 129: Octave Sharpening Python Plugin

129Download the Video! (77.0 MB, 40:31)
Download the Companion File!

This is the second time I try to get into Python scripting for GIMP. My script in the first show about scripting was simple, just saving some clicks. Now it is more complicated, variables, loops and floating points included. But no parrots!

You find a better version of the programs in the companion file. Following a tip in our Forum I included a Undo Group. So the action can be undone, a behaviour that should have been included from the start.

I mentioned some sources. Instant Python, the official Python Tutorial and the GIMP Python reference. Bert has a script page and a much better version of the Octave sharpening script.

Then we have a UnGIMP composition challenge on the Forum.

Have I forgotten some promised links? Please complain below!


The loop counter in the companion file is set to 6 instead of 4. You can change it back or leave it.

Perhaps it is better to take the image size from drw instead of img. See the discussion in the forum. drw.height and drw.width should work also when the layer is smaller than the image.

Creative Commons License
Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
Permissions beyond the scope of this license may be available at http://meetthegimp.org.

Episode 080: Hi Bert! (Ernie not included)

Download the Video!
Download the companion file! (…if there is one…. ;-) )

80This show is two days late – lots of work and again some eye trouble. This time the other one – but it is working out.

Bert (Ray Adagio on the Forum) is the star of this episode. He has written some great scripts and enhanced others, the Zone Adjustment script for example. And now he has tackled rotation. You just have to mark two points on a vertical or horizontal line and click – the rotation starts. Ok, the tool from the toolbox has way more options, but usually you don’t need them.
Bert has also started a discussion about sharpening in different colour modes. Sharpeneing the “L” of LAB should be the best way, but this involves a lot of lossy math in 8 bit mode. Forget about it. But sharpening the “V” of HSV can be an alternative.

The animation in this post has a lot of artifacts due to the 256 colours of the GIF image. The real ones are better. All the example images are in the companion file of episode 79, not 78 as I said in the video. Only the one with selective sharpening is in the ZIP file for this episode.

I add a way to do a selective or high pass filtering in HSV. Perhaps in a script on a server near you in the future. ;-)

Sharpening is a topic that has to covered in later episodes. On can sharpen a colour channel (gree is best most of the time) or use different values for the USM (unsharp mask) algorithm. How that thing really works would be interesting too.

Information about the DOCMA Award 2009 can be found in the forum. I’ll update that tomorrow.


00:30 DOCMA Award Challenge
02:30 Subscribe and donate
04:20 Writing scripts
05:00 Rotation script
06:20 Install a script
08:00 Missing folders – no problem
08:45 Using the Rotation script
11:25 Sharpening in LAB?
12:30 HSV and LAB
14:45 Differences between RGB, HSV and LAB sharpening
20:40 Conclusion
21:15 Decompose
22:00 Unsharp mask
23:30 Adding a layer mask for selective sharpening
24:00 Edge detection
25:30 Temporary layer for controlling the effect
27:30 Recompose the image
29:00 Adding an image into a new layer
30:00 Conclusion – there are more ways….

Creative Commons License This work is licensed under a
Creative Commons Attribution-Share Alike 2.0 Germany License.

Episode 058: White is Grey – and Black too!

Download the Video!
Download the companion file!

Finally the “Zone Adjustment Plugin” – formerly known as “Meaningful Black Script” is shown in its full glory. You find it here and in the companion file.

EDIT: This plugin has evolved tremendously. Go to the Forum entry and search from the last postings backwards for it’s latest incarnation!

And I present a plugin for displaying EXIF information in an image, a split toning plugin and a plugin for applying the “Lazlo Dragan effect”. (Download should now be possible without need to register – sorry, made a mistake in the configuration.) All were published in the Forum of Meet the GIMP.

You can find information about the installation of these plugins there too. Basically you just copy them into your plugin directory (not the scripts directory) and make them executable. The last step is not necessary under Windows.

The show starts with a short introduction into the Zone System of Ansel Adams. Before we go deeper into this, we have to calibrate our cameras. Set your camera to manual mode, set the metering to spot or center based and shot a well exposed image of something middle grey or whitish with a bit of structure in it. I took a white door, but raw concrete is fine too. Then shoot two series of images, the first one closing down one stop in each image, the other in opening up one stop for each step. We’ll look at my images next week.

The TOC:

Ansel Adams and the Zone System 0:27
Calibrating your camera for the Zone System 7:00
Plugins in the Forum 9:36
Working with the “Zone Adjustment Plugin”, formerly know as “meaningful Black” 11:25
Detaching menues in GIMP 12:23
Sample Points 12:50
Finding the Dark and Bright point 15:25
Using the plugint 19:40
The proof: white is grey – and black too! 25:25

The image used in this podcast was made during a performance of Pascale Loiseau from the Belgian  WAZOVOL artists group. I found a video of her performance.

Edit: I changed “script” to plugin – there is a bit of confusion….

Creative Commons License This work is licensed under a
Creative Commons Attribution-Share Alike 2.0 Germany License.