How to implement object detection using opencv or any other library in android

Blessings - image analysis is not something for which there is a clear solution nor something that can be patched up quickly.

OpenCV has a sample project with autolearning for face recognition though, it needs to be taught and I can't say if it's good or bad - I work in image analysis but from a different perspective.

You should find some good books on Image Processing like "Digital Image Processing: PIKS Inside, Third Edition. William K. Pratt" (ISBN: 0-471-37407-5) or "The image processing handbook, John C. Russ" (ISBN: 0‑8493‑7254‑2) to get a hold of the main problematics with this field.

Also, delve deep into OpenCV documentation, to have a preliminary knowledge of the problem it took me almost a week.

Face recognition in particular has deep roots in Artificial Intelligence because algorithmic, deterministic approaches tend to be unreliable due to the sheer number of small variations in the image processed that can completely mislead the algorithms.


EDIT: sorry, I was talking about face detection and you were asking for object detection.

In this case it's even worst than face detection because you have to know what you're looking for. The best way to start implementing object recognition is to turn the image in graylevel and woprk your way out with Sobel or Laplace operators to get the edges of the image. From then on it is a matter of logic to discriminate objects with respect to background, similar objects, junctions of objects and so on.

Hope to be of help,
Denis