The format you select determines whether the image is saved with all its layers or if it is flattened.

SketchBook supports TIFF, BMP, GIF, JPEG, png, and PSD. When saving your work, you can save out an alpha channel and choose the file format. If it would just kill you to lose your work, back it up! Saving in SketchBook Pro Desktop The mobile versions have options for exporting to Dropbox, etc. No matter where your drawings are stored, we highly recommend you back them up.

If you're on an iOS device, we highly recommend checking out the section on saving to the cloud to protect your work. Since this isn't the ideal solution, we've added the iCloud storage option. If the app is ever deleted, your files are deleted, as well. If you are using SketchBook Pro Mobile on iOS, the files are saved within the Gallery, which is part of the app. This means if the app is ever deleted, your sketches still exist elsewhere. Some versions of SketchBook save your files on the device or machine in a separate folder for the app.

Autodesk sketchbook pro ipad