So this is interesting: the Sailor Moon Cosmos Arc, a fan manga (doujinshi) made by digitally altering Naoko Takeuchi’s original manga images. The fan artist is OhtoriArt (formerly Vivian exMoon), who is also an avid cosplayer.
(I suggest not reading it unless you’ve read/seen all the Sailor Moon stories to avoid spoilers. Also, read it right-to-left.)
I think even the goal of this doujinshi is impressive – first, you have to have a story idea, plot it out, write it, and storyboard it. Then, among the many volumes of Sailor Moon, you have to search for the closest original image that you can work with. Then you have to alter it the way you want and match the alterations’ visual quality to the source material.
Here are some more examples of just how extensive the modifications can be. I have a little retouching experience – it’s hard! It takes a lot of Photoshop layers, that’s for sure.
I have a volume of Card Captor Sakura that is falling apart, and the two-page spread of when The Flower first appears is loose now, so I decided to color it with colored pencils. This is a photocopy, though, since I want to try out different color combos.