Photo editing is a hobby for many. It is not really difficult but it needs some special skills to do it well.
This is less about how to improve photos, more about montages and collages. That means the change of image content and the assembling of multiple parts to create a new image. You might need it for a Facebook profile, a birthday card or you online shop.
There are numerous programs for image editing, such as Adobe Photoshop, Photoshop Elements, Gimp (it's free), and more from manufacturers such as Magix and Corel. In addition, you'll find simple freeware programs, like Gimp, but less complex. Usually they use similar techniques and tools.
Some correction options for images are covered here as well, but less in terms of optimization than bringing several motifs together. So that they fit harmoniously together to form something new. The content of the e-book proceeds from basic knowledge to advanced techniques.