A jp2 decoder and PNG encoder based on CGI using openjpeg

Demo: http://openjpeg.kbresearch.nl/jp2demo2/index.html?urn=ddd:010461485:mpeg21:p001:image

tested on openjpeg2.0

This project includes an installer for ubuntu distribtions: install-ubuntu.sh - NO GUARANTEES

To compile this project has dependencies on the following maintained packages:

• libcurl4-*-dev
• libpng12-dev

And on the sources of the openjpeg2.0 project hosted via google code.

The project has been tested with 64-bits distro's of Ubuntu 12.04 and 32-bit CentOS 6.4

After successful compilation (make) the two binaries are built in the project directory:

• jp2.cgi
• jp2-cache-clean

To check the compiled cgi script from bash try the following (should output a JSON response): export QUERY_STRING=f=./balloon.jp2; ./jp2.cgi

After successful installation (sudo make install) the above binaries will have been copied to:

• /usr/lib/cgi-bin/jp2.cgi
• /usr/local/bin/jp2-cache-clean

To check for success try the following url (should respond with a valid JSON encoded error: "No resource specified"):

• http://localhost/cgi-bin/jp2.cgi

As per your apache2 configuration it might be necessary to add this (very insecure) entry to you httpd.conf or apache2.conf or suchlike:

<Directory "/usr/lib/cgi-bin">
    Options +ExecCGI
</Directory>

For the script to work a caching directory with read/write access has to be available for apache2 (the www-user). This directory defaults to:

• /var/cache/jp2

To change the caching location an environment variable needs to be configured through the cgi module (/etc/apache2/mods-enabled/cgi.load):

• SetEnv JP2_CACHEDIR "/path/to/cache"

Now the following url display a PNG file decoded from the sample image hosted on github:

• http://localhost/cgi-bin/jp2.cgi?u=https%3A%2F%2Fgithub.com%2Frenevanderark%2Fjp2png-web-cgi%2Fblob%2Fmaster%2Fballoon.jp2%3Fraw%3Dtrue&t=1&r=3

Keep your cache dir clean. That's what the other binary is for. Test it out like so:

• ./jp2-cache-clean

Add an entry to your crontab (somewhat) like the following to clean the cache every minute:

• */1 * * * * /usr/local/bin/jp2-cache-clean --cache-dir /var/cache/jp2 --max-size 1024 2>> /var/log/jp2-cache-clean.log

The cgi scripts supports the following parameters (setting either 't' or 'u' shows only the header information in JSON):

• 'f': reference to a local filename of a.jp2 file
• 'u': url encoded reference to a remote filename (URL) of a.jp2 file
• 't': the tile to be decoded (now the response should become a .png file)
• 'r': resolution level (which is a reduction factor when decoding)
• 'x': x-position within the decoded tile
• 'y': y-position within the decoded tile
• 'w': width of the decoded tile (x+w should not exceed the total width of the tile)
• 'h': height of the decoded tile (y+h should not exceed the total height of the tile)
• 'n': number of compositions of the tile (max supported is shown in the jp2 header; 1 becomes grayscale in all cases)
• 'j': when added the service returns a JPEG encoded tile in stead of a PNG encoded tile
• 'c(allback)': jsonp callback for remote origin website JSON support

Skip all that and symlink the demo like this:

• cd /var/www
• sudo ln -s /path/to/project/demo
• open a browser and surf to: http://localhost/demo/

Logging of the web service is directed by default to the apache error log (/var/log/apache2/error.log)

There are two logging settings available which can be changed through Apache's environment variables (editable through /etc/apache2/mods-enabled/cgi.load). These flags are optional:

• SetEnv JP2_VERBOSE 1
• SetEnv JP2_SUPPRESS_ERRORS 1