...
1. A user wants to repeat/draw a picture. He has two options: to find it by name/author/style using a search text box (see below) or if he sees a picture at the moment, he can just photo it (after pressing "Search by Photo" button). So, the user chooses one picture he would like to train on. 
2. The user takes a sheet of paper and redraws the picture, step-by-step. 
3. The user always sees the original picture on his phone (or he can send it to a printer via smartphone and get a paper copy of the picture). He can always check his progress by pressing the "Check Progress" button, taking a picture of the current results. The application will automatically compare the original picture with the user's one and will show the progress and similarity percentages.
So, the user can learn a style of drawing by searching and choosing one picture of that style, and trying to redraw it. The application will help to do it and will show results and progress over time.
...