[Gdal-dev] Kakadu float rasters and 16bits lossless

[Frank Warmerdam]

Julien Demaria wrote:
> Hi,
> 
> The Kakadu driver can create float rasters and compress 16bits rasters 
> lossless, so this line in the driver sources should be updated :
> 
>         poDriver->SetMetadataItem( GDAL_DMD_CREATIONDATATYPES,
>                                    "Byte Int16 UInt16" );
> 
> and also the driver documentation 
> (http://gdal.maptools.org/frmt_jp2kak.html) :
> 
> "... When reading images this driver will represent the bands as being 
> Byte (8bit unsigned), 16 bit signed or 16 bit unsigned.
> ...
> NOTE: QUALITY=100 will not be lossless for 16bit images."

Julien,

Have you verified broadly that 16bit signed and unsigned images can be
compressed losslessly?  I can't remember why I put this comment in the
document, but I am hesitant to remove it without being able to remember.

Also, the floating point support depends on the data being prescaled between
0.0 and 1.0 which is then internally implicitly treated as integers as I
understand it.  So I don't think there is really proper support for floating
point data, though I didn't realize when I first implemented the code.

Best regards,
-- 
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