http://saaspose.com/blog/saaspose-slides/archive/2012/11/25/convert-presentations-to-images-and-extract-text-from-images-using-saaspose-rest-api.html

While processing your presentations you may come across scenarios where you need to convert the presentations to images using Saaspose.Slides and recognize text from images using Saaspose.OCR. Saaspose.Slides is a REST API that allows you to create, modify and convert presentations in the cloud whereas Saaspose.OCR is a REST API for optical character recognition and document scanning. Using these two REST APIs you can work with conversion of presentations and text recognition from images.