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IIPImage - High Resolution Streaming Image Server

GPLv3 Licensed Build Status Build Status CodeQL Coverity Scan CodeFactor


IIPImage is an advanced high-performance feature-rich image server system for web-based streamed viewing and zooming of ultra high-resolution images. It is designed to be fast and bandwidth-efficient with low processor and memory requirements. The system can comfortably handle gigapixel size images as well as advanced image features such as 8, 16 and 32 bits per channel, CIELAB colorimetric images and scientific imagery such as multispectral images, image sequences and 3D surface topologies.


  • Fast lightweight FastCGI server
  • High performance with inbuilt configurable cache
  • Support for extremely large images: tera-pixel and multi gigapixel support
  • TIFF and JPEG2000 input support
  • JPEG, PNG and WebP output support: export of whole or regions of images at any size
  • Supports IIP, Zoomify, DeepZoom and IIIF API's
  • 1, 8, 16 and 32 bit image support including 32 bit floating point support
  • CIELAB support with automatic CIELAB->sRGB colour space conversion
  • Multispectral and hyperspectral image support
  • Image stacks and image sequence support
  • Dynamic hillshading of 3D surface topologies
  • Dynamic watermarking
  • Memcached support


Detailed class descriptions (generated using doxygen) are available in the doc subdirectory


iipsrv is released under the GNU General Public License (GPL). See the copyright notice COPYING in this directory for licensing details or go to for more details.

If you use IIPImage on a public site and remove the IIP link logo from the client, you must provide a link on your site back to the IIPImage site -

This distribution includes version 2.4.0 of the FCGI development libraries. See COPYING.FCGI for licensing information for these libraries.


Requirements: libtiff, zlib and the IJG JPEG development libraries. Optional: libmemcached (for Memcached), libpng( for PNG output), libwebp (for WebP output) and Kakadu or OpenJPEG (for JPEG2000 input).

Plus, of course, an fcgi-enabled web server. The server has been successfully tested on the following servers:

Example server configurations are shown below.


The standard autoconf build process should work fine. If you want to allow dynamic loading of 3rd party image decoders, use the configure option --enable-modules. There is a version of the FCGI development library included in this distribution. The configure script will use this bundled version unless it detects one already installed. Alternatively, you may specify the path using --with-fcgi-incl= and --with-fcgi-lib=.

If this is an SVN or Git development version, first generate the autoconfigure environment using


Otherwise for release versions, use configure directly:



IIPImage is able to use Memcached (, a high-performance, distributed memory object caching system. If enabled, IIPImage will cache results using Memcached, giving IIPImage added speed and scalability. To use this, you will need to install the library (and development files) of libmemcached ( This will be automatically detected during the build process.


IIPImage is able to decode JPEG2000 images via the Kakadu SDK ( This is, however, not open source and you will need to purchase a license for the source code. In order to use, first build the Kakadu SDK as per the instructions supplied with the SDK. Then, supply the following parameters to the ./configure command



IIPImage is able to decode JPEG2000 images via the open source OpenJPEG library ( Activated if OpenJPEG development files found in system path or path provided via


OpenJPEG will be disabled if Kakadu support has been requested or --disable-openjpeg used.


Simply copy the executable called iipsrv.fcgi in the src subdirectory into the web server fcgi directory. If one does not exist, simply create one, called, for example, fcgi-bin. The web server will need to be configured to use this executable.


There are several startup variables that can be passed to the server. They are all optional.

LOGFILE: the server will log its output to the file specified, if it can. Version 1.1 and later of iipsrv also supports logging to syslog if “syslog” is given as the value.

VERBOSITY: 0 means no logging, 1 is minimal logging, 2 lots of debugging stuff, 3 even more debugging stuff and 10 a very large amount indeed ;-)

MAX_IMAGE_CACHE_SIZE: Max image cache size to be held in RAM in MB. This is a cache of the compressed JPEG image tiles requested by the client. The default is 10MB.

FILESYSTEM_PREFIX: This is a prefix automatically added by the server to the beginning of each file system path. This can be useful for security reasons to limit access to certain sub-directories. For example, with a prefix of "/home/images/" set on the server, a request by a client for "image.tif" will point to the path "/home/images/image.tif". Any reverse directory path component such as ../ is also filtered out. No default value.

FILESYSTEM_SUFFIX: This is a suffix added to the end of each file system path. It can be combined with FILESYSTEM_PREFIX. It is not used in combination with FILENAME_PATTERN. If e.g. this is set to ".tif", an image URL such as "/UUID" will look for "${FILESYSTEM_PREFIX}/UUID.tif". In the IIIF info.json document, the image @id will be set without the ".tif" suffix.

JPEG_QUALITY: The default JPEG quality factor for compression when the client does not specify one. The value should be between 1 (highest level of compression) and 100 (highest image quality). The default is 75.

PNG_QUALITY: The default PNG quality factor for compression when the client does not specify one. The value should be between 1 (highest level of compression) and 9 (highest image quality). The default is 1.

WEBP_QUALITY: The default WebP quality factor for compression when the client does not specify one. The value should be between 0 (highest level of compression) and 100 (highest image quality). The default is 50.

MAX_CVT: Limits the maximum output image dimensions (in pixels) allowable for dynamic image export via the CVT command or for IIIF requests. This prevents huge requests from overloading the server. The default is 5000. If set to -1, no limit is set.

ALLOW_UPSCALING: Determines whether an image may be rendered at a size greater than that of the source image. A value of 0 will prevent upscaling. The default is 1 (upscaling is allowed).

MAX_LAYERS: The maximum number of quality layers to decode for images that support progressive quality encoding, such as JPEG2000. Ignored for other file formats. If not set, half of the available quality layers will be decoded by default. If set to -1, all the available layers will be decoded by default.

FILENAME_PATTERN: Pattern that follows the name stem for a 3D or multispectral sequence. eg: "pyr" for FZ1_pyr_000_090.tif. The default is "pyr". This is only relevant to 3D image sequences.

WATERMARK: TIFF image to use as watermark file. This image should be not be bigger the tile size used for TIFF tiling. If bigger, it will simply be cropped to the tile size. If smaller, the watermark will be positioned randomly within the available space. The image can be either colour or grayscale.

WATERMARK_PROBABILITY: The probability that a particular tile will have a watermark applied to it. 0 means never, 1 means always.

WATERMARK_OPACITY: The opacity (between 0 and 1) applied to the watermark image.

MEMCACHED_SERVERS: A comma-delimitted list of memcached servers with optional port numbers. For example: localhost,,

MEMCACHED_TIMEOUT: Time in seconds that cache remains fresh. Default is 86400 seconds (24 hours).

INTERPOLATION: Interpolation method to use for rescaling when using image export. Integer value. 0 for fastest nearest neighbour interpolation. 1 for bilinear interpolation (better quality but about 2.5x slower). Bilinear by default.

CORS: Cross Origin Resource Sharing setting. Disabled by default. Set to * to enable for all domains or specify a single domain. See for more details on CORS.

BASE_URL: Set a base URL for use in certain protocol requests if web server rewriting has taken place and the public URL is not the same as that supplied to iipsrv.

URI_MAP: Set a mapping from a URL prefix to a supported protocol. This enables iipsrv to be able to work without requiring full CGI query strings. Map must be of the form "prefix=>protocol" where prefix can be either empty or any string prefix and protocol must be one of IIP,IIIF,DeepZoom, Zoomify. Used, for example, to map requests of the form http://server/iiif/ to the IIIF protocol handler without requiring web server rewriting.

CACHE_CONTROL: Set the HTTP Cache-Control header. See for a full list of options. If not set, header defaults to "max-age=86400" (24 hours).

EMBED_ICC: Set whether the ICC profile is embedded within the output image. 0 to strip profile, 1 to embed profile. The default is 1 (embedded profiles).

OMP_NUM_THREADS: Set the number of OpenMP threads to be used by the iipsrv image processing routines (See OpenMP specification for details). All available processor threads are used by default.

KAKADU_READMODE: Set the Kakadu JPEG2000 read-mode. 0 for 'fast' mode with minimal error checking (default), 1 for 'fussy' mode with no error recovery, 2 for 'resilient' mode with maximum recovery from codestream errors. See the Kakadu documentation for further details.

IIIF_VERSION: Set the major IIIF Image API version. Values should be a single digit. For example: 2 for versions 2 or 2.1 etc. 3 for IIIF version 3.x. If not set, defaults to version IIIF 3.x

DECODER_MODULES: Comma separated list of external modules for decoding other image formats. This is only necessary if you have activated --enable-modules for ./configure and written your own image format handler(s).


The images paths given to the server via the FIF variable must be absolute paths on the server machine (eg. FIF=/images/test.tif) and not paths relative to the web server document root location. Images do not, therefore, need to be directly accessible by the client via the web server. Make sure the server process owner is able to access and read the images!


Apache and mod_fastcgi

httpd.conf example extract:

# Create a directory for the iipsrv binary
ScriptAlias /fcgi-bin/ "/usr/local/httpd/fcgi-bin/"

# Set the options on that directory
<Directory "/usr/local/httpd/fcgi-bin">
   AllowOverride None
   Options None

# Syntax for access is different in Apache 2.4 - uncomment appropriate version
# Apache 2.2
#   Order allow,deny
#   Allow from all

# Apache 2.4
   Require all granted


# Set the module handler
AddHandler fastcgi-script fcg fcgi fpl

# Initialise some variables for the FCGI server
FastCgiServer /usr/local/httpd/fcgi-bin/iipsrv.fcgi \
-initial-env LOGFILE=/tmp/iipsrv.log \
-initial-env VERBOSITY=2 \
-initial-env MAX_IMAGE_CACHE_SIZE=10 \
-initial-env FILENAME_PATTERN=_pyr_ \
-initial-env JPEG_QUALITY=50 \
-initial-env MAX_CVT=3000 \
-listen-queue-depth 2048 \
-processes 1

Apache and mod_fcgid

mod_fcgid is a binary compatible replacement for mod_fastcgi. It works in the same way, but is configured differently. Load the module like this:

LoadModule fcgid_module /path/to/apachemodules/

Here is an example configuration. Note that mod_fcgid does not have a FastCgiServer directive and there is no need to explicitly start the server:

# Create a directory for the iipsrv binary
ScriptAlias /fcgi-bin/ "/var/www/localhost/fcgi-bin/"

# Set the options on that directory
<Directory "/var/www/localhost/fcgi-bin/">
   AllowOverride None
   Options None

# Syntax for access is different in Apache 2.4 - uncomment appropriate version
# Apache 2.2
#   Order allow,deny
#   Allow from all

# Apache 2.4
   Require all granted

   # Set the module handler
   AddHandler fcgid-script .fcgi

# Set our environment variables for the IIP server
FcgidInitialEnv VERBOSITY "5"
FcgidInitialEnv LOGFILE "/tmp/iipsrv.log"
FcgidInitialEnv MAX_IMAGE_CACHE_SIZE "10"
FcgidInitialEnv JPEG_QUALITY "50"
FcgidInitialEnv MAX_CVT "3000"

# Define the idle timeout as unlimited and the number of
# processes we want
FcgidIdleTimeout 0
FcgidMaxProcessesPerClass 1


Note that on CentOS, FcgidIPCDir is configured by default to /var/log/httpd/fcgidsock, which may not be writable by Apache. If this is the case, specify another location for FcgidIPCDir, which is writable, such as /tmp/fcgidsock


lighttpd.conf example extract:

fastcgi.server = ( "/fcgi-bin/iipsrv.fcgi" =>
  (( "host" => "",
     "port" => 9000,
     "check-local" => "disable",
     "min-procs" => 1,
     "max-procs" => 1,
     "bin-path" => "/var/www/localhost/fcgi-bin/iipsrv.fcgi",
     "bin-environment" => (
        "LOGFILE" => "/tmp/iipsrv.log",
        "VERBOSITY" => "5",
        "MAX_IMAGE_CACHE_SIZE" => "10",
        "FILENAME_PATTERN" => "_pyr_",
        "JPEG_QUALITY" => "50",
        "MAX_CVT" => "3000"


iipsrv can also be used with NginX. The one drawback with regards to iipsrv is that it cannot automatically spawn FCGI processes, so you will need to use nginx together with spawn-fcgi or start iipsrv from the command line.

To set up nginx with iipsrv add a directive such as this to your nginx configuration, which will forward requests to /fcgi-bin/iipsrv.fcgi to a running iipsrv process on port 9000.

location /fcgi-bin/iipsrv.fcgi {
	fastcgi_pass    localhost:9000;
	fastcgi_param   PATH_INFO $fastcgi_script_name;
        fastcgi_param   REQUEST_METHOD $request_method;
        fastcgi_param   QUERY_STRING $query_string;
        fastcgi_param   CONTENT_TYPE $content_type;
        fastcgi_param   CONTENT_LENGTH $content_length;
        fastcgi_param   SERVER_PROTOCOL $server_protocol;
        fastcgi_param   REQUEST_URI $request_uri;
        fastcgi_param   HTTPS $https if_not_empty;

Nginx can also handle load balancing to multiple iipsrv instances, which can be hosted on the same machine on multiple ports or on different hosts. For a multiple host configuration, declare the load balancing like this:

upstream iip {

and change the fastcgi_pass parameter in the above location configuration to point to this instead of a fixed address:

fastcgi_pass       iip;


iipsrv can also be used with lighttpd's spawn-fcgi without the need for a full web server. Simply spawn the iipsrv process on the command line. The process can be bound to an IP address and port for backend load-balancing configurations. For example:

spawn-fcgi -f src/iipsrv.fcgi -a -p 9000


Simply run the MyServer configuration and in the MIME section, choose the .fcgi extension and select:

MIME Type: application octet-stream
Action: Execute self contained FastCGI
Manager: NONE 

Java Application Servers (Tomcat, Jetty, JBoss etc)

IIPImage can also be used with Java Application Servers such as Apache Tomcat, JBoss and Jetty. Simply add the JFastCGI jar file to your webapp and add the following to your web.xml configuration file in order to re-route FCGI requests to the IIPImage server on the specified port.

<!-- Gateway Servlet to IIPImage FCGI server -->



You then need to start an instance of the server on the requested port (6667 in this example) using spawn-cgi (see spawn-cgi section above) or on the command line (see below).

Command Line

It is also possible to start iipsrv directly on the command line using the --bind parameter. For example:

iipsrv.fcgi --bind

where the argument given to bind is the socket on which to listen to FCGI requests. Note that these are not HTTP requests and iipsrv will still require a web server front-end.

There is additionally a --backlog parameter that is optional and sets the socket backlog value. The backlog value specifies the number of requests can be queued and, therefore, increases the number of concurrent connections that iipsrv can handle and is set to 2048 by default. For example:

iipsrv.fcgi --bind --backlog 1024

Note that the backlog parameter must be specified after the bind parameter and argument. Note also that this value may be limited by the operating system. On Linux kernels < 2.4.25 and Mac OS X, the backlog limit is hard-coded to 128, so any value above this will be limited to 128 by the OS. If you do provide a backlog value, verify whether the setting /proc/sys/net/core/somaxconn should be updated.

Your web server should, therefore, be configured to use this address for FastCGI. For example with lighttpd:

fastcgi.server = (
  "/fcgi-bin/iipsrv.fcgi" => (
        ("host"=>"", "port"=>9000, "check-local"=>"disable")

For Apache, load mod_proxy and mod_proxy_fcgi and add the following line to Apache's configuration:

ProxyPass "/fcgi-bin/iipsrv.fcgi" "fcgi://"

Please refer to the project site for further details

(c) 2000-2023 Ruven Pillay