I'm a complete beginner in image processing thing so please do excuse me if my question is foolish .Basically I'm trying to develope an image filter app .So, when I googled I came to know that both openCV and openGL can be used for this purpose .
But I'm not sure which language would be the best means by speed or efficiency ?
Can anyone please enlighten me about this topic a bit?
OpenGL stands for Open Graphics Library. It is a 3D graphic rendering library.
OpenCV stands for Open Computer Vision. It is a computer vision library dealing with on real-time image processing.
If you want to create 3D images, you use OpenGL. If you want to make the computer understand the imagery, you use OpenCV.
Regarding your usecase, ie image filtering, OpenCV is the best for you.