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fvar

$ \bigcirc$Name


fvar Compute the variance of the gray level of an image




$ \bigcirc$Command Synopsis


fvar A .



A : input fimage

. (screen output) : output variance




$ \bigcirc$Function Summary


float fvar (A )

Fimage A ;




$ \bigcirc$Description


fvar returns the variance of the gray level of an image, estimated by

var = $\displaystyle {\frac{1}{{m \cdot n-1}}}$$\displaystyle \sum_{{1\leq x \leq m, \,1 \leq y \leq n}}^{}$$\displaystyle \big($A(x, y) - M$\displaystyle \big)^{2}_{}$

and

M = $\displaystyle {\frac{1}{{m \cdot n}}}$$\displaystyle \sum_{{1\leq x \leq m, \,1 \leq y \leq n}}^{}$A(x, y).

The result is zero if the domain of A contains less than 2 pixels.




$ \bigcirc$See Also


faxpb, frandphase.


$ \bigcirc$Version 1.1


Last Modification date : Thu Nov 29 20:23:56 2001


$ \bigcirc$Author


Jacques Froment






next up previous contents index
Next: mschannel Up: Reference Previous: fsize   Contents   Index
mw 2004-05-05