Adobe has released its first iPad app for Apple's new device, which started shipping today in the US. Adobe Ideas is a free digital sketchbook app that's designed to allow artists to sketch ideas wherever they are, before bringing the results into Photoshop or Illustrator back in the studio.

Ideas features simple vector-based drawing tools with separate drawing and photo layers. There are brush for digital painting, which control of the szie of a brush being through the iPad/iPhone's two-fingered pinch/stretch gesture.

The app can automatically create of harmonised colour schemes based on photos or other images (below), in a similar way to Adobe's Kuler website, or Pantone's myPantone website and iPhone app.

Adobe says that the zoom control enables you to zoom in and out on projects without jaggies or big pixels. Other features include a vector eraser and 50 levels of undo. Finished sketches can be emailed as PDFs for use in other projects.

The app sees competition from two paid-for rivals Autodesk SketchBook Pro for the iPad and Brushes.