Loading TIF images in Ubuntu

I have some problems loading TIF images using Qt.

Googling gave me this:
http://doc.qt.io/qt-5/qtimageformats-index.html

The actual coding and decoding of the file format is done by a codec library. The codec can be Qt or third party code. In case of a third party codec, the build process will look for it among the system libraries. If not found, it may fall back on using a bundled copy (in src/3rdparty).

On my own machine (Linux Mint 17.1, Qt 5.3.2 compiled from source), the return value of

Code:

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QImageReader::supportedImageFormats()

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includes "tif" and "tiff". and consequently such images load fine.

On a friend's machine (Ubuntu 14.04, Qt 5.2.1 that came with the installation), supportedImageFormats() does not include "tif". However,

Code:

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locate libtiff

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on the command prompt shows
/usr/lib/x86_64-linux-gnu/libtiff.so.5
/usr/lib/x86_64-linux-gnu/libtiff.so.5.2.0

As per the quote above, I expected Qt to find the codec "among the system libraries". What need to be done to ensure that?

First of all check if your friend's Qt installation includes qtiff plugin like your does.

$ ls -1 /usr/lib/x86_64-linux-gnu/qt4/plugins/imageformats

libqgif.so
libqico.so
libqjpeg.so
libqmng.so
libqsvg.so
libqtga.so
libqtiff.so

Yes, he gets the exact same list of libraries, including libqtiff.so

Does running ldd on libqtiff.so report any missing dependencies? Make sure you are checking the appropriate Qt installation!

>ldd /usr/lib/x86_64-linux-gnu/qt4/plugins/imageformats/libqtiff.so
linux-vdso.so.1 => (0x00007fff287c9000)
libtiff.so.5 => /usr/lib/x86_64-linux-gnu/libtiff.so.5 (0x00007f76882b7000)
libQtGui.so.4 => /usr/lib/x86_64-linux-gnu/libQtGui.so.4 (0x00007f7687604000)
libQtCore.so.4 => /usr/lib/x86_64-linux-gnu/libQtCore.so.4 (0x00007f768711e000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f7686e1a000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f7686c04000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f768683e000)
liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f768661c000)
libjbig.so.0 => /usr/lib/x86_64-linux-gnu/libjbig.so.0 (0x00007f768640e000)
libjpeg.so.8 => /usr/lib/x86_64-linux-gnu/libjpeg.so.8 (0x00007f76861b8000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f7685f9f000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f7685c99000)
libfontconfig.so.1 => /usr/lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f7685a5c000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f768583e000)
libaudio.so.2 => /usr/lib/x86_64-linux-gnu/libaudio.so.2 (0x00007f7685626000)
libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f768531d000)
libpng12.so.0 => /lib/x86_64-linux-gnu/libpng12.so.0 (0x00007f76850f7000)
libfreetype.so.6 => /usr/lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f7684e54000)
libgobject-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 (0x00007f7684c02000)
libSM.so.6 => /usr/lib/x86_64-linux-gnu/libSM.so.6 (0x00007f76849fa000)
libICE.so.6 => /usr/lib/x86_64-linux-gnu/libICE.so.6 (0x00007f76847de000)
libXi.so.6 => /usr/lib/x86_64-linux-gnu/libXi.so.6 (0x00007f76845cd000)
libXrender.so.1 => /usr/lib/x86_64-linux-gnu/libXrender.so.1 (0x00007f76843c3000)
libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f76841b1000)
libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f7683e7b000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f7683c77000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f7683a6f000)
/lib64/ld-linux-x86-64.so.2 (0x00007f768874d000)
libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f7683844000)
libXt.so.6 => /usr/lib/x86_64-linux-gnu/libXt.so.6 (0x00007f76835de000)
libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f76833d9000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f768319b000)
libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007f7682f93000)
libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007f7682d8d000)
libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f7682b6e000)
libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f7682967000)

It seems they're all there.
My simple testprogram (which doesn't print "tif") looks like so:

Code:

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#include <QApplication>
#include <QImageReader>
#include <QList>
 
int main( int argc, char **argv )
{
    QApplication app( argc, argv );
 
    QList<QByteArray> foo = QImageReader::supportedImageFormats();
    foreach (QByteArray b, foo)
    {
        qDebug("%s", qPrintable(QString(b)));
    }
 
    exit(0);
}

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How come libqtiff resides in qt4's plugin directory rather than in qt5's ?

I tried running strace (a program that logs all syscalls with arguments and return values) on the test program above to possibly get more detailed error-info. The string "tif" was nowhere to be found in the log. There was plenty of references to the qt5/plugin directories, but none to the qt4/plugin directories.
In desperation, I made a symlink to qt4/plugins/imageformats/libqtiff.se in the corresponding qt5 directory, but to no avail.

Quote:

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Originally Posted by drhex

How come libqtiff resides in qt4's plugin directory rather than in qt5's ?

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Apparently you are checking Qt4 installation and not Qt5 :)

Your friend probably doesn't have the qt5-image-formats-plugins package installed.

Confirmed. Installing qt5-image-formats-plugins fixed the issue.