My thoughts about Optical flow has stayed at the late 80s for a long time. For me, optical flow equals to Lukas-Kanade. Until very recent, I found that there are many other good optical flow methods published in top conferences, like CVPR, ICCV. There is also a library – middlebury to test some tough problems within the computer vision area, such as stereo, optical flow. Moreover, the optical flow code written by Prof. Michael Black is very reliable, http://www.cs.brown.edu/~black/.
It is said Nikon is the only camera vendor that provides in camera multiple exposure SLR cameras.
—-Nikon D200 digital SLR camera
Multiple exposure enables up to 10 separate images to be used to create a single composite to produce imaginative and even surreal results. Image overlay function creates a composite image in-camera from two selected NEF (RAW) images. The original files remain unaltered, opacity can be precisely controlled and the resultant image can be saved in either RAW, JPEG, or TIFF format.