Fix overflow in subsampling for preprocessing
Fix overflow in subsampling for preprocessing

Thanks to David, he found that an image of 43345 x 52036 causes an
int32 overflow. I should have better thought that through. Anyways,
fixed now!.

NeoGeographyToolkit/StereoPipeline,NeoGeographyToolkit/StereoPipeline,ScottMcMichael/StereoPipeline,ScottMcMichael/StereoPipeline,DougFirErickson/StereoPipeline,aaronknister/StereoPipeline,NeoGeographyToolkit/StereoPipeline,DougFirErickson/StereoPipeline,DougFirErickson/StereoPipeline,NeoGeographyToolkit/StereoPipeline,aaronknister/StereoPipeline,DougFirErickson/StereoPipeline,ScottMcMichael/StereoPipeline,NeoGeographyToolkit/StereoPipeline,njwilson23/StereoPipeline,oleg-alexandrov/StereoPipeline,ScottMcMichael/StereoPipeline,aaronknister/StereoPipeline,DougFirErickson/StereoPipeline,oleg-alexandrov/StereoPipeline,njwilson23/StereoPipeline,ScottMcMichael/StereoPipeline,oleg-alexandrov/StereoPipeline,njwilson23/StereoPipeline,oleg-alexandrov/StereoPipeline,aaronknister/StereoPipeline,ScottMcMichael/StereoPipeline,oleg-alexandrov/StereoPipeline,njwilson23/StereoPipeline,oleg-alexandrov/StereoPipeline,DougFirErickson/StereoPipeline,njwilson23/StereoPipeline,njwilson23/StereoPipeline,aaronknister/StereoPipeline,NeoGeographyToolkit/StereoPipeline