[Digikam-devel] [digikam] [Bug 360714] JPGEG2000 thumbnails shows as dimension 0x0 pixel

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=360714

caulier.gilles at gmail.com changed:

           What    |Removed                     |Added
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                 CC|                            |caulier.gilles at gmail.com

--- Comment #4 from caulier.gilles at gmail.com ---
Ulrich,

The informations displayed by Exiftool are just image pixels properties. This
is not the real image metadata, know as Exif, Iptc, and XMP.

The way that digiKam save to new JPG2000 has visibile metadata, is that digiKAm
genrate basic Exif, Iptc and XMP from image properties + digiKam properties.
That all.

The problem about the null thumbnail is simple. With JPEG2000, we don't load
full image to render thumb, as JPEG for ex. IPTC as a properties to store a
dedicated image preview that we use instead to render thumb. In your case, no
IPTC = no thumb.

Why not to load full JPEG2000 image to render thumb ? simple : jasper library
used to decode JPEG2000 is old, not maintained and generated a lot of non
catch-able exception which crash digiKam as well. 

The alternative to this problem is to use http://www.openjpeg.org/ instead. But
rewriting JPEG 2000 decoder is a non trivial task, and require time to do...

Alternative to JPEG2000 : PGF or WebP. Both use wavelets compression. The first
one is fully supported to digiKam. The second one must be implemented.

Gilles Caulier

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