How to get raw data using OpenCV APIs

Hi all When I am using cvCaptureFromCAM and cvQueryFrame(), it creates image frames in RGB24 format. My Logitech camera generates YUV image. My query is How to disable this YUV to RGB conversion in the OpenCV? I don't want the image in the RGB format. Neither I want to convert the image using OpenCV APIs to YUV in the code. All I want is the raw image generated by the camera as-is. Is that possible in OpenCV? If yes then kindly guide me. Thanks Neha