[fdo-internals] Re: FDO raster image data model does not provide the actual number of bits used by certain image data formats (Re: FdoRfc1 & FdoRfc2)

Frank Warmerdam warmerdam at pobox.com
Thu Mar 22 11:49:24 EDT 2007

Jeff Childers wrote:
> ATIL will report any range information found encoded in Image Format
> files should that information be present. It simply reports this
> differently than the bitsUsed information as having precise range
> information is not common in formats and ATIL does not sample the data
> to determine a range for all image types. 
> I do know for certain that if range information is encoded in TIFF that
> it is reported, although that information is not always accurate.
> Perhaps GDAL encodes this faithfully, but I find a majority do not.


GDAL does not currently encode min/max information in TIFF.  You are certainly
correct that when available, the information is not always accurate, but I'm
not sure that is a good reason to always disregard it.

It is excellent news that ATIL does support returning min/max metadata for

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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