broken support for chroma-subsampled images

[Benjamin Gilbert]

On Thu, Mar 16, 2017 at 08:54:22PM +0000, Coudray, Nicolas wrote:
> openslide.lowlevel.OpenSlideError: Cannot read this file because your OS
> vendor ships a modified version of OpenJPEG with broken support for
> chroma-subsampled images.  OpenJPEG error: Error decoding tile.  Component
> 1 contains only 32768 blocks while component 0 has 65536 blocks
> 
> We tried to download openslide from the 3.4.1 source and also via the
> distribution packages.  We tried to upgrade to openjpeg 2.1.1 as suggested
> on some forums, but it hasn't solved the problem.
> 
> Our system is
>     CentOS Linux release 7.3.1611 (Core)

Hi Nicolas,

The RHEL 7 bug report is marked ON_QA, so I'm assuming Red Hat will release
a fixed OpenJPEG package soon.

    https://bugzilla.redhat.com/show_bug.cgi?id=1207473

Until then, the easiest fix is indeed to install OpenJPEG 2.1.x.  After
doing that, you will need to compile OpenSlide from source, and you should
verify that the configure script finds your OpenJPEG 2.x installation.  If
you installed OpenJPEG to /usr/local, you will likely need to run
"export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig" before running configure.

--Benjamin Gilbert