Iam using Opencv 2.4.3 , my grpahic card is ATI , but I keep reading that CUDA is Nvidia enabaled , does this mean I can't use gpu functions as long as I have ATI graphic card ?
Indeed, CUDA Technology is exclusive to NVIDIA devices, so ATI video cards doesn't support it.
However, OpenCV 2.4.3 was the first version to support OpenCL. There has been a considerable amount of changes to the ocl module since it was first released, so I suggest you upgrade to a more recent version.
You might be able to enjoy OpenCV's GPU processing if your ATI video card supports OpenCL.