Python Image Library fails with message "decoder JPEG not available" - PIL

Extending Pillow's image handling capabilities

To fully exploit Pillow's myriad functionalities, you might want to support other image formats too. In this case, install these additional packages:

• libfreetype6 and libfreetype6-dev for font manipulation.
• zlib1g-dev for PNG files and images using ZIP compression.

Implement the installations with:

sudo apt-get install libfreetype6-dev zlib1g-dev

Replacing outdated PIL with its well-maintained fork — Pillow often helps overcome JPEG decoding issues. To ensure smooth transition, use --no-cache-dir flag when reinstalling to fetch the latest version:

pip install Pillow --no-cache-dir

Tackling system-specific issues

Ubuntu and Debian

If you face recognition issues post-installation, create symbolic links for the libraries:

ln -s /usr/lib/x86_64-linux-gnu/libjpeg.so /usr/lib   # creates a scenic route for libjpeg, so it doesn't get lost!
ln -s /usr/lib/x86_64-linux-gnu/libfreetype.so /usr/lib   # libfreetype likes to take the scenic route too!
ln -s /usr/lib/x86_64-linux-gnu/libz.so /usr/lib   # And last but not least, libz joins the trip!

macOS

On Mavericks, preset the ARCHFLAGS environment variable to compile PIL/Pillow accurately:

export ARCHFLAGS="-arch x86_64"  # Let's keep the architecture in line, shall we?

Red Hat based systems

On such systems, use yum with the following command:

sudo yum install --assumeyes libjpeg-devel

Regardless of the specific system, always reinstall Pillow once the respective libraries are installed, to activate JPEG support.

Additional pointers

Review your PYTHONPATH

Ensure your PYTHONPATH environment variable contains the path to your Pillow/PIL library files. If it doesn't, consider adding this to your .bashrc or .bash_profile for permanent access.

Upgrading PIL on YUM systems

Want the latest version of your PIL library on YUM systems? Say no more:

sudo pip-python install --upgrade PIL     # Because you deserve only the best!

Digging deeper into the issues

If the usual remedies don't work, it's a sign that you might be dealing with version incompatibilities or a missing library. A regular reinstall might not do the trick and fetching the library from a third-party source might be required. In such cases, assist pip with some additional flags:

pip install --global-option=build_ext --global-option="-I/usr/local/include" --global-option="-L/usr/local/lib" Pillow  
# Must go to 'Pip's secret stash' for niche libraries sometimes!