[Gdal-dev] RE: Strange NoData value from a MrSID image (Peng Gao)

[Peng Gao]

> > If this is 8-bit data, then we should be using
getSampleValueUint8(),

> > not getSampleValueFloat32().

> >

> > The "datatype" in those function name refers to the underlying
datatype

> > of the sample, not the desried return type or such.  I think I even

> > documented that :-)

> 

> Michael,

> 

> Ah!  Thanks, I'll fix that.  This would certainly explain why Peng was

> getting junk values.

> 

> ... I see Andrey has beat me to it.  Thank goodness for CVS reporting

> via IRC.

> 

 

I have a question about the interpretation of MrSID NoData value. 

Is a pixel considered NoData only if all three values match their

corresponding band NoData value, or Is a pixel considered NoData

if any band value matches band NoData value? For example, given

NoData values (0, 0, 0), Are only those pixels with value (0, 0, 0)

considered NoData, or (0, x, x), (0, 0, x), and etc considered

as NoData pixels as well?

 

Gao, Peng

 

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