What is OpenCv and JavacV? please give simple introduction or meaning.Please tell me how useful in programming language.
OpenCV is a library that is used for computer vision applications. It is originally made for C/C++. JavaCV is a Java implementation of the same API. What are you planning to use it for? If you only know Java you may be able to make due with JavaVC. If you plan to work on an embedded system OpenCV is definitely the way to go. I hear Khronos will soon be releasing an early version of OpenVX which is a hardware accelerator for OpenCV.
Here is the OpenCV API: http://docs.opencv.org/index.html