GIMP

Installation

On Windows, GIMP can be installed with Chocolatey:

choco install -y gimp

Selection

Magic Wand

Change size of selection by holding mouse clicked and moving the mose up/down or left/right, respectively. (This was useful to select signature).

Un-select a selection

ctrl+shift+a or Menu Select -> None.

Add a region to or remove a selection from an existing selection

Use the lasso together with shift (add) or ctrl (remove).

Make selection transparent

In layer window, choose Layer -> Transparency -> Add Alpha Channel then use del key or Menu Edit -> Clear.

Draw straight lines

Choose desired «instrument» (pencil etc.)

Click start point with mouse on starting point

Release mouse

Press and hold shift

Click next point.

In order to draw horizontal or vertical lines (or of some predefined angles), press and hold shift and ctrl.

Color space

Some images (gifs?) might have a reduced color space («indexed colors») and therefore, it seems impossible to draw in the color chosen in the «color box».

In this case, the color space needs to be changed (possibly to RGB) in the Menu Image -> Mode)

(Some) shortcuts

ctrl-b

Open «Werkzeugkasten

(Some) Menus

Filters -> Script Fu -> Console opens the Script-Fu Console

Directory for Script-Fu scripts: Edit -> Preferences -> Folders -> Scripts

Resizie an image: Image -> Scale Image

Command line arguments

`-v`	`--version`	Show version information and exit
	`--license`	Show license information and exit
	`--verbose`	Be more verbose
`-n`	`--new-instance`	Start a new GIMP instance
`-a`	`--as-new`	Open images as new
`-i`	`--no-interface`	Run without a user interface
`-d`	`--no-data`	Do not load brushes, gradients, patterns, ...
`-f`	`--no-fonts`	Do not load any fonts
`-s`	`--no-splash`	Do not show a splash screen
	`--no-shm`	Do not use shared memory between GIMP and plug-ins
	`--no-cpu-accel`	Do not use special CPU acceleration functions
	`--session=<name>`	Use an alternate sessionrc file
`-g`	`--gimprc=<filename>`	Use an alternate user gimprc file
	`--system-gimprc=<filename>`	Use an alternate system gimprc file
`-b`	`--batch=<command>`	Batch command to run (can be used multiple times)
	`--batch-interpreter=<proc>`	The procedure to process batch commands with
`-c`	`--console-messages`	Send messages to console instead of using a dialog (`(gimp-message …)` ?)
	`--pdb-compat-mode=<mode>`	PDB compatibility mode (off\|on\|warn)
	`--stack-trace-mode=<mode>`	Debug in case of a crash (never\|query\|always)
	`--debug-handlers`	Enable non-fatal debugging signal handlers
	`--g-fatal-warnings`	Make all warnings fatal
	`--dump-gimprc`	Output a gimprc file with default settings
	`--show-playground`	Show a preferences page with experimental features
	`--display=DISPLAY`	X display to use

Then, there is also -h, --help, --help-all, --help-gegl, --help-gtk

Links

Gimp in the Microsoft Store.