Error Concealment | JPEG | MPEG-4 | Wavelet | YUV

Hi all!! I have a few questions that i am having difficulty with. How 
do we find the global motion parameters using the gradient method??? 
also how are these parameters used to relate the edges of one image to 
the edges of another image in case of Image Registration??? Can 
someone pls help me out with this quickly....If some one could provide 
me with the code for this...it would be of great help!!!!

Thanks in Advance!!!

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