File Split

[Cao Kang]

Hi,
I have spent several days on the customized file input format in hadoop.
Basically, we need split one giant square shaped image (.tif) into four
square shaped smaller images. Where does the really split happen?  Should I
implement it in "getSplits" function or in the "next" function? It's quite
confusing.
Does anyone know or can anyone provide some examples of it? Thanks.