Image editing Paid API for iOS

I am working on iPhone application in which I nee开发者_运维知识库d to implement editing image properties. If user select an image, can able to change brightness, contrast, saturation, etc and can write some text in image background/foreground. I any one worked on this type please give reference or sample code. or any free or paid API for this will help me a lot

Ex:http://www.wordfoto.com/

Thanks, Aaryan

---

I used Apple's GLImageProcessing example project to add image filtering capabilities to one of my apps.

The project contains Brightness, Contrast, Saturation, Hue rotation and Sharpness image filters. The issue is that the project is using the opengl framework. Not so simple to modify and tweak if you never using opengl before