[gdal-dev] NoData vs metadata confusion

[Oyvind Idland]

Thanks for fast reply !

I assume the IMAGE__NO_DATA_VALUE=255,255,255 comes from the MrSid SDK
library.

These values could easily be mapped to the GDAL-bands NoData, as they
practically means
the same ? (255 for each band)


-- Oyvind


On Thu, Oct 28, 2010 at 1:09 PM, Chaitanya kumar CH
<chaitanya.ch at gmail.com>wrote:

> Oyvind,
>
> GDAL handles nodata values band by band, whereas in MrSID all the bands of
> the particular pixel location must match the nodata values for that pixel to
> be considered nodata.
> Currently nodata values are ignored in this driver. I don't know if
> anything is planned for future releases.
>
> On Thu, Oct 28, 2010 at 4:21 PM, Oyvind Idland <oyvind.idland at gmail.com>wrote:
>
>> Hello,
>>
>> stumbled across a problem when reading MrSid:
>>
>> The MrSid dataset contains 3 bands, R/G/B. None of the 3 bands gives me a
>> GetNoDataValue(),
>> however, the metadata contains IMAGE__NO_DATA_VALUE=255,255,255.
>>
>> Does this mean, that I have to check for both cases ?
>>
>> The version is GDAL 1.7.2.
>>
>>
>> Regards,
>>
>>
>> Oyvind Idland
>>
>> _______________________________________________
>> gdal-dev mailing list
>> gdal-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>
>
>
> --
> Best regards,
> Chaitanya kumar CH.
> /tʃaɪθənjə/ /kʊmɑr/
> +91-9494447584
> 17.2416N 80.1426E
>
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