You can get a free license for AKVIS software by translating our texts (3-4) from English to Japanese.
If you are interested, please contact us at firstname.lastname@example.org
The author of this tutorial is Alvaro Salazar Chacon.
The AKVIS SmartMask plug-in can be used to change the background of an image (the following example the sky) regardless of the complexity of objects in the landscape.
Now you can create landscapes with different backgrounds: