XnSketch is an iPad app that allows you to take pictures on your iPad and turn them into cartoons or add sketch effects to your pictures. You can also use the app to affect the color saturation and clarity of your pictures. All of the images that you alter in XnSketch can be saved to your camera roll or shared to other applications on your iPad.
If you’re looking for a simple tool that students can use to enhance their pictures to use in comic strips that they’re creating in your classroom. If they want to use their XnSketch images in a Google Presentation they could share them to Google Drive through their iPads.