GIMP: The missing tutorials



During the past 10 or so years, I was reading and watching a tremendous amount of tutorials for the software I am using. Typically I have an issue to solve and then search for a tutorial that shows me how to solve it. Over the years, there have been many issues that come over and over again, but I was never able to find decent tutorials for. In this thread, I want to encourage you to help me with regard to three tasks,

  • identifying more oft-required topics where the tutorial landscape is thin or the tutorials are lacking particular aspects,
  • collecting tutorials that helped you with the issues others did not find decent tutorials for, and
  • if you are that skilled (or even if you are able to teach yourself that way) to contribute the missing tutorials.

These can be very little tasks or extremely sophisticated ones, whatever you like. I want to start this discussion about GIMP since it is probably the most versatile tool for FLOSS photographers. We can of course start similar threads for other tools if required.

What I personally expect from a decent tutorial landscape to one particular topic is that at least several difficult cases are covered by one or several tutorials and that the material used in the tutorial is available to try it at home (of course only if applicable).

So I will start the collection:

  • Free-form selection of difficult opjects, especially people with particular hair styles: The classic one. There are many tutorials around and even special tools to do this kind of selection in GIMP but I had a hard time to get particular difficulties sorted: Many good tutorials solve the issue for images with a low resolution, but I required solutions for >24 MP files for large prints that should not be scaled down; Several tutorials work well for the example picture, even if it has difficult hair, but never worked for one of my pictures; Some techniques work for blending with special colours but fail for others; Sometimes, the combination of several techniques is required, and I did not find a good solution for storing and/or seamlessly combining the separate masks into one mask.
  • Adding shadows in composings: While the principle is covered in several tutorials, there are a lot of open questions. There seem to be tools in commercial software that ease some of them, but I struggle to find a good workflow in GIMP. Particular issues are: What are the options to form an authentic shadow for an object or person; How to deform the shadow to make it fit the three-dimensional landscape (e.g. shadow on a house wall, on a little hill, shadow broken into parts by obstacles etc.); How to find the “correct” shadow colour?
  • Applying decent colour looks: It seems i have a great deficiency when it comes to colour. This one is not so special about GIMP but I think the technical side could be covered by GIMP very well and it would be not that difficult to transfer it to other tools. Especially, I am not able to find reasonable colour looks for particular situations and even if I have an idea I struggle with modeling it in GIMP or darktable. Especially mixed light situations seem difficult, how to e.g. solve typical christmas pictures with flash, different electric and candle light? How to make pictures look dark without losing too much dynamic range, or, in different words, how dark has a picture to be to look dark, and which colour looks are reasonable; How to deal with different extreme skin tones, e.g. when my wife gets extremely red cheeks in warm environment and my son besides looks pale like a zombie, is it possible to reduce the difference? I tried a lot to study pictures I like to solve the issue, but am not able to apply it on both sides, the tool and the imagination. So this topic may be split into the tool and the mind part, and for the latter, it may be useful if there were some guided tours for studying pictures.

What are your issues? Are you able to recommend tutorials for one of the issues in this thread? Or did you solve one by yourself and give some hints or even contribute a tutorial? Here’s the stage …


Not good style to answer myself here, but I just discovered that a question was asked earlier today that perfectly fits into the topic:

(Martin Scharnke) #3

When queried by Pippin, Gandalf put his conversation with himself this way: “choosing the wisest person to speak to.”:grinning::sunglasses:

(Pat David) #4

This is such a ridiculously complex problem, unfortunately, that I fear that a single tutorial might not be very useful for many use-cases. :frowning: There’s been some headway made with mattin FG selection tools in GIMP, but for the most part it’s a non-trivial problem (across all software really, the Ps users don’t get it much easier than we do).

This is one of those things that I think gets easier with practice and/or exposure to 3D modeling. That is, being able to spatially project how you imagine a “realistic” shadow might fall on the scene, particularly in regards to objects/terrain. I’d love to see some good examples of approaches others have seen/used to tackle this.

This is one of those things that requires a good grasp of the tools available and how to visually segment a scene for various results. Mixed lighting has always been a real pain the butt, but if you have some logical places to cut the scene, or methods for masking the scene that don’t look too strange, you can probably get away with fixing it.

Maybe something with two different WB exports that can be blended manually? (Assuming the images exist as raw and are able to be balanced well). This is another case where it’s highly dependent on the image and the breadth of knowledge of the tools.

In any case, I’m all ears for good tutorial ideas. (On a side note, I am also quite ready to assist anyone who wants to write and publish something - just let me know!)