Category Archives: Programming

Episode 187: Cleaning Up

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187Download the Video! (35:45 68.1MB)

The last episode got a lot of comments – thank you all for them! And in this episode I try to follow all of the tips you gave me. I remember layer groups and drop shadows, see that Alpha to selection is really better and fight with Copy&Paste in the text tool.

I got a present too – a fine script in Scheme for generating the title screen. Of course that has to be explored. Did you know that you can export the content of a selection as a new image by key stroke? I found out about SHIFT-CTRL-V. Saul’s script gets also a first analytical look – Scheme looses its terror if you come close.

Matthias pointed to an other Colour Design site and the GIMP Magazine will publish a new issue next week.

And finally I take a good look at the “Blender Master Class”, a very fine book about the 3D software Blender.

The TOC

00:00:00 Intro
00:00:40 Using chapter marks in the video
00:01:30 Layer groups
00:05:23 Alpha to Selection – better than selecting by color
00:09:00 Drop shadow filter
00:10:10 Copy and Paste with the text tool is a bit broken
00:13:37 A script in Scheme
00:14:12 Exporting selections from GIMP as graphic image files / Create from clipboard
00:15:20 Exporting vs. saving – don’t discuss, just follow your orders! ;-)
00:16:30 Installing a Scheme (.scm) script
00:17:30 Testing the script
00:18:45 Comparing the results
00:19:30 Analyzing the script
00:25:40 Thanks to Saul Goode
00:26:16 Another Color Design website
00:26:45 GIMP Magazine launch ahead
00:27:30 Book review: Blender Master Class, Ben Simonds
00:35:45 End of video

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

Getting the focus distance out of Nikon NEF files

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The lensfun tab in UFraw does not read the distance information for Nikon lenses, because the .NEF files do not record a value for SubjectDistance in the EXIF data. But the information is in there – only not in a standard way.

In some circumstances the subject distance is essential for lens corrections. Then you have to enter the value by hand. mac has written a script that can extract the distance information under Linux and perhaps MacOS.

When you run the script by typing FD in a terminal, it asks you for the full path to the folder where your image files are.  It then prints the file names and their focus distances to a file called FocusDistances.txt in the same folder as the images.

As usual, you have to copy the script as root or with “sudo” to /usr/local/bin and make it executable.  It also assumes you have exiftools installed.

And here is the script:


#!/bin/sh
#   This script prints the focus distance for all image files in the specified folder
#   to an output file called 'FocusDistances.txt' in the same folder
echo ""
echo "~*~*~*~*~*~*~*~*~*~*~*~*~*"
echo "Extract Focus Distance information"
echo "~*~*~*~*~*~*~*~*~*~*~*~*~*"
echo ""
echo
echo -n "Enter path to directory with the images, and press Enter"
echo
echo
read directoryname
exiftool -p '$filename Focus Distance = $FocusDistance' $directoryname > /$directoryname/FocusDistances.txt
echo ""
echo "~*~*~*~*~*~*~*~*~*~*~*~*~*"
echo "All done!"
echo ""
echo -n "                Press any key to finish…"
echo
read answer
exit 0
# Save this script as "FD", and, as root, copy it to /usr/local/bin/
# To use it, type "FD", enter the full path to the source directory, press ENTER
# and wait for the script to finish.  Press any key to continue.
#  Last updated 14/7/2010

As you can see by the date this has sat on my mail account for quite a while nd mac had to remind me of posting it. So if I have promised you something, just drop me a line. There was so much to think of here recently that I tend to forget stuff.

Episode 144: Greek Scripts

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Download the Video! (110.2MB, 57:59)
Download the companion file with the images used

This is the first episode made by Philipp (note the missing “e”) and he has done an entire hour with two topics.

First he develops a script in Python for applying a vignette effect to your images. It shows that he is a much better programmer than me.

In the second part he has a shot of a “For Sale” poster (the self made ones with the phone number at the bottom for tearing off) in Greek and shows, how to make a version with your own believable text out of it.

You can get his original image and the script in the companion file. The XCF is lost, sorry.

My only contribution is slapping the music and bumpers on and the image on the right which has a vignette and Python written in Greek. ;-) If you like Phillip’s show, shower him with nice comments here. Perhaps he will make more shows then. :-)

Meet the GIMP will make a video publication break until the first week in September. I’ll use the time to move and settle, clear up the blog and server, work out the feed and torrent problems, get the mobile version running again and hopefully produce some shows in advance for filling weeks suffering of time theft. Then I’ll be back on a regular one week schedule – it is better for me and you.

Up to now there is no TOC for this show.

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 130: Getting the Bugs out

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130Download the Video! (61.2 MB, 32:10)
Download the Companion File! (767 Bytes!)

Sorry, again a “Nerd Show”. I tackle some problems that have come up with the Python script of the last week and show my way to debug and test while making errors. My first error was to take a test case without colours – my script from last week changed all images to greyscale. Then I learn something useful about merging layers in Python.

But the top of the show is even more nerdy – the Octave plugin allows to access the Octave math software from GIMP. Caluculate your images or do a FFT with them.

The scripters crowd in the forum found a bug in GIMP, saulgoode reported it and it got fixed in a day. Take that, Adobe! ;-)

Then I try to explain why the big blobs in the image featured two shows ago are not made with GIMP but with pure physics in the camera. You can see a Blender video I made about this for #200 of Chris Marquards Tips from the Top Floor show. My part starts at about 11:40 and contains an embarrassing error. Do you get it?


 This image by Nachbarnebenan is a good example for a shallow DoF.

The next show will be a simple, non-nerd walk through the post processing of an image. Promised.

The TOC

01:10 Octave Math Plugin
02:10 Number types in Python
06:00 Making a test case
06:30 Finding the wrong layer mode
08:00 Running into a wall and thinking around it
09:40 Isolate the bug
12:40 Cleaning up the code
14:40 Colour halos wit Normal Mode sharpening
16:40 When to use Octave sharpening
17:10 Basics of Photography – Depth of Field and Bokeh
19:00 Image creation with a lens
21:00 Circle of Confusion
22:30 Depth of Field
25:00 Apperture and DoF
28:30 DoF and sensor size
29:00 Dofmaster
30:00 Focal length and DoF

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 129: Octave Sharpening Python Plugin

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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!

Errata:

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 061: Up to the Stars!

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

Made by Philippe DeMartinDownload the Video!
Download the companion file!

This week I have outsourced the show again! Philippe will take us all along to a ride to the stars – building an image like this one from scratch.

The TOC will follow when I have seen the video again – I was so absorbed that I forgot to make notes.

I promised a link for the “User Filter”, which allows to use Photoshop filters in GIMP.

Do you like this kind of GIMP usage in the show? I come from the photographic side and made this podcast according to the stuff that I can do. But with Phillippe’s help a lot more is possible. What do you think? Post your comments here!

Episode 060: Divide!

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Download the Video!
Download the companion file!

Today I have a mixture of 3 topics for you. An other try to tackle the basics of the Zone System, a way to choose the right way through the maze of different ways to tackle a problem in Gimp and a method to counter vignetting and light falloffs with a layer in divide mode.

Before one of you comments about making vignettes: Just invert the mask and you have a vignette. ;-) Looks fine with a lot of images and John Arnold uses them all the time.

TOC

Setting display options 0:30
Zone System Philosophy 3:24
How to chose a way to tackle a problem in Gimp 10:20
Correct a vignette or light falloff 18:22
Using burn mode to emphasize colours 23:30

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

How to install Python plugins under GIMP

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Please read the comments – some important stuff may have shown up!

Linux – with GUI

Check that the packet gimp-python is installed.

Copy your .py file into the directory .gimp2.4/plug-ins (replace 2.4 with your GIMP version number, 2.6, 2.7, soon 2.8 or, to be future proof, 3.0 ;-) ) . This is a hidden directory, you don’t see it in the file browser. With Nautilus you can toggle the display of the hidden files with Ctrl-H.

Then make the file executable by right clicking, selecting “Properties” from the menue and activate “Execute” in the permissions tab.

If GIMP was running, restart it.

Linux – with commandline

Check (with synaptic) that the packet gimp-python is installed.

Enter this:

cp myfile.py ~/.gimp2.4/plug-ins
chmod u+x ~/.gimp2.4/plug-ins/myfile.py

If GIMP was running, restart it.

Mac OS

Please write an instruction into the comments – I’ll pull it up to here.

Look through the comments for a solution – but I think there must be a better one.

EDIT by monoceros84: There is a new discussion going on in the forum. Have a look at: http://forum.meetthegimp.org/index.php/topic,227.0

Windows

Copy the files to ~/.gimp2.4/plug-ins

With the following prerequisites:

- PyGTK, PyCairo and PyGobject (all available from the GNOME FTP mirrors as installers) are installed prior to installing GIMP
- ~ is %USERPROFILE%

If GIMP was running, restart it.

Why Python?

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I got this mail from Marc (posted with permission):

Rolf writes in his blog:

> I need help with learning enough Python to write scripts for GIMP.
> Do you know a good site or other ressource? Mail me!

Why Python? I played with that language many years ago. I don’t remember anything special that would make me want to use it over the scheme based scripting language.

Example, here’s a script to increase contrast in an image, written shortly after I saw you do it in one of podcasts :-) It copies the current layer twice naming them “pop” and “pop-ovly” then sets the mode of pop-ovly to overlay (5) and the opacity to 50 percent. That’s it. I can then adjust the opacity for the amount of “pop” I want and then do a merge-down leaving me with a layer “pop” that has the adjustment.

following are two scripts, an analysis and the same script in Python. Boring for some….
Continue reading →