Real Sketch is a drawing application for artists and students. It has various tools that let you draw on any surface, using your camera or a photo on your phone. It's perfect for beginners and professionals, for planning a painting before you start drawing, or for positioning a scene on your page.

The free version of the app includes the AR Tracing feature which works like a lightbox, but a more versatile one. It also has a color mixer that lets you use a painter's color wheel. To fully enjoy the app's capabilities, you can get its premium version. One of the premium features is the tonal values tool that lets you view a picture in grayscale. 

You can use Real Sketch to draw a portrait, a landscape, or a building. It can be used for any kind of drawing, even if you're not a professional. It's perfect for those who want to learn to draw.