Computes flow for every pixel of the first input image using Lucas & Kanade algorithm


- prev (IntPtr)
- First image, 8-bit, single-channel.
- curr (IntPtr)
- Second image, 8-bit, single-channel.
- win_size (MCvSize)
- Size of the averaging window used for grouping pixels.
- velx (IntPtr)
- Horizontal component of the optical flow of the same size as input images, 32-bit floating-point, single-channel.
- vely (IntPtr)
- Vertical component of the optical flow of the same size as input images, 32-bit floating-point, single-channel.