images: added imagemagick and rotate guide

wiki/imagemagick.md

@@ -0,0 +1,20 @@
+# ImageMagick
+
+[ImageMagick](https://imagemagick.org/) is a free and open-source, cross-platform software suite for
+displaying, creating and editing (raster) images.
+
+## Usage
+
+The following section addresses different uses ImageMagick.
+For most of ImageMagicks features the [command-line interface](/wiki/system_console.md) can be used.
+
+## Rotate an Image
+
+To rotate an image and save the edited copy of the image run the following command.
+`origin.png` is the image to be rotated and `target.png` is the rotated image.
+`90` is the degrees the image `origin.png` will be turned by.
+Change these values as needed.
+
+```sh
+convert origin.png -rotate 90 target.png
+```

wiki/images.md

@@ -13,6 +13,9 @@ In the computer context it is a file with an extension like `png`, `jpg`, `gif`
 Editing images can be done by various image manipulation software.
 A popular cross-platform program for this is [GIMP](https://www.gimp.org/).
 
+A second cross-platform software suite for displaying, creating and editing (raster) images is
+[ImageMagick](/wiki/imagemagick.md).
+
 Another part of image manipulation is the upscaling of low resolution images.
 This can be done by the cross-platform program [upscayl](https://github.com/upscayl/upscayl).