[gdal-dev] Reading jpeg 2000 compressed nitfs

[Frank Warmerdam]

James,

I have reviewed nitfdataset.cpp and jpeg2000dataset.cpp
(the JasPer driver) and I believe they are now compatible.
That is, nitf now uses the /vsisubfile/ mechanism to
operate on the jpeg2000 data stream and I see the
JasPer driver now uses the VSI*L API needed to support
the /vsisubfile/ mechanism.

However, most NITF files I have worked with that
had jpeg2000 compression had single large
compressed images, not many small tiles.
The JasPer library does *not* provide an effective
mechanism to read subareas so for a large image
it tends to use as much as 10 times as much memory
as would be needed to hold the decoded image.
This makes it impractical for many geospatial
applications.

So I am still dubious about using it.

Best regards,

On Tue, Jan 26, 2010 at 9:12 AM, jim hopper <JAMES.E.HOPPER at saic.com> wrote:
> I read the item about lack of support for the J2K_SUBFILE mechanism using
> jasper, and that it requires one of the commercial jpeg2000 drivers.  Is
> that still the case, or Is there a way to read jpeg2k nitfs with open source
> jpeg2k libraries?
>
> Best jim
>
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