OhioLINK is not participating in the Google Summer of Code this year (too many other things going on for our staff to be effective mentors), which is why it is refreshing to see work on the wider adoption of JPEG2000 — one of our core goals — continue on other fronts. Among this year’s 900 projects accepted by mentors are two that involve J2K. All of this is welcome news, coming in the same month that Adobe is questioning the need for JPEG2000 support in Photoshop. My public gratitude goes out to Google for their third year of offering financial and logistical support to their Summer of Code program.

JPEG2000 in Firefox

JPEG2000 in FFMPEG

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OhioLINK was excited and privileged to participate in the second annual Google Summer of Code — a program to inspire young developers and provide students in Computer Science and related fields the opportunity to do work related to their academic pursuits during the summer, and to support existing open source projects and organizations. This is the first of three posts summarizing the efforts of three students; this one details the work of Juan Pablo Garcia Ortiz, a Ph.D. candidate at the University of Almeria in Spain, to build a JPEG2000 JPIP Streaming Server and Client Browser Viewer Applet. This is an edited version of his final report.

The final applications are the ‘jpip_server‘ and the ‘J2KViewer‘ — both of which can be found in the OhioLINK subversion repository. Please note that both are built atop the Kakadu JPEG2000 code library, only a portion of which is included in the OhioLINK subversion repository. ¹

JPIP Streaming Server

The multi-threaded mechanism is implemented with the Linux ‘pthread’ library and uses one thread for each client socket. The source code is written in C++, using the STL library to simplify the code, making it more legible, and orienting it to the object oriented programming philisophy. The different modules of the program are:

• report.cpp (report.h): For the class ‘report’, used to generate the applications logs.
• sock.cpp (sock.h): For the class ‘sock’, used to simplify the sockets work in Linux.
• j2k.cpp (j2k.h): Contains the class ‘j2k_image_file’, used to abstract the work with J2K images. It also contains the necessary code to initialize the Kakadu message handling system.
• jpip.cpp (jpip.h): Contains several classes to support a basic version of the JPIP protocol, over the Kakadu library.
• jpip_server.cpp: The main module.

It is recommended to start from a freshly unpacked (but not yet build) version of the Kakadu library source code (version 5.1). To build this JPIP, follow these steps:

1. At the top level of the Kakadu source directory, checkout the ‘jpip_server’ directory from the OhioLINK Subversion respository. The Subversion URI is https://drc-dev.ohiolink.edu/svn/jpip_server/
2. Change the current directory into ‘jpip_server’ and call the script ‘kakadu_rebuild‘. The script will create the Kakadu directory structure, apply some necessary patches, and build the Kakadu libraries. Please note that this script was written for Kakadu version 5.1 and the patches may not be required in subsequent versions.
3. Run ‘make’ (inside the jpip_server directory)

The accepted parameters by the server can be seen executing ‘jpip_server -u’. The images served by the server must be, by default, in the same directory. The command line option ‘-ipath’ allows you to define a base path for all the requested images. This server can be tested with the ‘kdu_show’ application of the Kakadu package. (kdu_show is a Windows application, but can be executed in Linux with WINE without problems.)

JPIP Browser Applet

1. Checkout of the ‘J2KViewer’ directory from the OhioLINK Subversion respository. The Subversion URI is https://drc-dev.ohiolink.edu/svn/J2KViewer/.
2. From within the J2KViewer directory, run ‘make’.

The build process creates a JAR file containing the viewer applet. It’s correct use would be to sign it with a official signature and include it into the appropriate Web page as an applet. The applet accepts the following parameters:

• “Image“: required, specifies the JPEG2000 image to view. If it’s a local image (not typical), this would be a path name (for example ‘/home/jportiz/image.jp2‘). If it’s a remote image (the typical usage) through the JPIP server, it would be a JPIP URI (for example, ‘jpip://server:9000/image.jp2‘). Do not include any JPIP parameters in this URI.
• “MiniViewWidth“: optional, specifies the width, in pixels, of the mini-view.
• “MiniViewHeight“: optional, specifies the height, in pixels, of the mini-view. The final mini-view size will be the maximum multiple by 2 size of the image that can be included within the specified mini-view size. By default, the mini-view size is 250×250.

To be able to test easily the applet, you can run ‘make test‘ to create a ‘test.html’ file and a ‘test’ script. This script launches the applet viewer with the ‘test.html’ page. It is necessary to modify the ‘Image’ parameter of this HTML page to set the appropriate image location.

To test the applet within a web browser, you can run ‘make test-signed‘ to create a signed JAR file, then open ‘test-signed.html’ with a Java compatible browser. Before opening the HTML page, it is necessary to modify the ‘Image’ parameter within the page to set the appropriate image location.

The viewer has a simple UI. It has a toolbar with two buttons, one to select the interaction mode (zoom or pan) and another one to show the mini-view window. There is a status bar where is showed the real image
size and the current scale, and in the right side, the current number of bytes read. In the center panel is the image — initially scaled by 2 fo fit it in the applet size. This behaviour can be modified easily in the code.

The mini-view window can be moved to any part of the main window. If it’s closed, it can be showed again with the associated button of the toolbar. The mini-view contains a red rectangle outlining the actual view of the main window. This red rectangle can be moved by dragging it and the corresponding view in the main window will be updated.

The applet requires that the Kakadu JNI library is stored in the user home directory (‘C:\Document And Settings\User’ in Windows and ‘/home/user’ in Linux). The applet detects if this library exists and if it is not found the applet allows it to be download automatically from the OhioLINK repository and stored it in the user home directory.

This is a brief description of the implemented classes:

• ChunkedInputStream: An InputStream derived class to decode HTTP chunked messages.
• HTTPMessage: The base class of all the HTTP message classes.
• HTTPRequest: Identifies a HTTP request.
• HTTPResponse: Identifies a HTTP response.
• HTTPSocket: Derives from Socket and allows HTTP messages to be sent and received in an easy way. In only supports send HTTP requests and receive HTTP responses (a client socket).
• ImagePanel: A GUI panel that can be included in any image browser. This panel has the necessary methods to load images and control its visualization. It supports the display of a mini-view of the image. All of the image navigation is controlled directly within this panel.
• ImageWindow: An interface to implement all the parent windows that include an ImagePanel obejct.
• J2KCache: A wrapper class for the Kdu_cache Kakadu class. This encapsulation allows another J2K engine to be used while avoiding the need to modify the design and code of the applet.
• J2KEngine: Contains all the necessary code to initialize the J2K engine. In our case, the Kakadu J2K engine.
• J2KException: A Exception derived class to identify the exceptions generated by the J2K code.
• J2KImage: This class contains all the necessary code to work with J2K images, local files as well as remote URIs. If the image is local, the Kakadu library functions are used to open it. If the image is remote, a J2KReader object is used to retreive the content.
• J2KImageView: Defines an image view, renderable on the screen. This image view is defined by its coordenates, size and resolution level.
• J2KReader: An implementation of a basic JPIP client to read the necessary data of a specific image view.
• J2KRender: Implements the rendering thread of the image browser. This thread is always generating the current image view. It stops when this view is rendered and the image content is completed (if the image is remote, this means that all of the required image codestream blocks have been received).
• J2KViewer: The main class of the application.
• JpipConstants: Defines several global constants related to the JPIP protocol.
• JpipDataInputStream: An InputStream-derived class to extract JPIP data segments from an input.
• JpipDataSegment: Contains the information of a JPIP data segment, which can be either an EOR message or a data-bin segment.
• Mutex: A simple mutex implementation in Java, used to avoid threads conflicts when accessing to the image data.
• StringInputStream: An InputStream-derived class to extract strings from inputs without buffering. Useful to decode HTTP headers and chunks lengths.

The viewer follows the JPIP philosophy in the code structure, especially with remote images. That is, when it is displaying a remote image, there are three threads running in parallel: one for the main GUI, a second for the JPIP comunication that is making the requests and filling the cache with the received data, and a third to render the cache content on the user’s display.

The Java JPIP viewer has been tested in Windows and in Linux. In Windows it has been used the Sun JVM/JRE 1.5 without problems. However, in Linux, this JVM/JRE version seems quite unstable, requiring the previous version, 1.4.2. In Linux the Blackdown JVM 1.4.2 as well as the Sun JVM 1.4.2 have been tested with succesful results.

Future Development Goals

Another feature that was part of the original design but was not completed due to time pressures was to integrate the JPIP server and client into the FEDORA digital object repository system. There is also room for a lot of more features: support of the HTTP-TCPtransport protocol, allow for the display of the image metadata, more GUI utilities like the ability to save the image as a local file for image processing, increase the set of supported JPIP parameters, etc.

Gratitude and Acknowledgements

The text was modified to remove a link to http://drc-dev.ohiolink.edu/browser/jpip_server/ on January 13th, 2011.

The text was modified to remove a link to http://drc-dev.ohiolink.edu/browser/J2KViewer/ on January 13th, 2011.

The text was modified to remove a link to http://drc-dev.ohiolink.edu/browser/jpip_server/kakadu_rebuild on January 13th, 2011.

Footnotes

1. Editorial comment: although not released with an open source license, the Kakadu JPEG2000 code library is available at a very reasonable cost. Juan Pablo’s efforts initially started with one of the open source JPEG2000 libraries, but it was quickly determined that the Kakadu library was required to meet the demands of the project proposal.

OhioLINK is pleased to mentor three students working on projects for Ohio’s higher education and libraries around the world during the Google Summer of Code 2006. The three projects are:

JPIP Browser Applet and Streaming Server

JPIP is Part 9 of the JPEG 2000 specification and is used to stream image codestream blocks to a client on demand. For instance, a JPIP client on a desktop may ask for a certain quality level and resolution of a region of an image. Using the JPIP protocol, the client makes such requests to a server and the server responds with only the image codestream blocks needed by the client. This saves the overhead of transmitting the entire image file when, say, only a thumbnail version is required.

The server side of the JPIP client/server pair will connect to OhioLINK’s existing FEDORA digital object repository. FEDORA is the “Flexible Extensible Digital Object Repository Architecture”, an open source digital object repository created by Cornell University and the University of Virginia. A key aspect of the Fedora software is its use of “disseminators” to create derivatives on-demand of datastreams stored in the digital object package.

Running in the user’s browser, the JPIP applet will request portions of a JPEG2000 image in FEDORA at a specified quality/resolution/clip and the FEDORA/JPIP disseminator will retrieve and return to the applet the requested precincts/packets directly from an archival master in the repository.

Communications System

The project consists of a set of two clients, written in Java, on the basis of the Internet Relay Chat (IRC) protocol. One client is targeted at patrons (readers, researchers, scholars, etc.); the other aims at facilitating the needs of librarians and other staff. The server end of the chat system consists of an IRC daemon. The clients, being pure Java, can easily be refitted into a number of embeddable modules, including browser applets, JNLP packages, NetBeans or Eclipse platform modules, etc. Using the ubiquitous and well-developed IRC as the underlying layer provides additional possibilities for sophisticated users and administrators, namely using IRC clients of their choice, using IRC bots when staff are unavailable, etc.

The project consists of two parts: the first being the implementation of a generic IRC client in Java with a GUI, and the second being the addition of advanced functionalities specifically for the purposes of OhioLINK and member libraries: identity branding; ability to store and send “canned” messages; ability to transfer patrons among librarians; ability to email transcripts of sessions; ability to automatically email transcripts at the close of a session; a survey for user feedback; and the ability to service / monitor multiple queues.

Video Snapshot Tool

This project will provide users with a capability to browse video collections to see ‘snapshots’ of what each video contains, with index pointers to characteristic frames (scene pointers), equally distant pointers, and user-defined pointers (which are saved within users profile, something like video-browsing history). There will be a timeline with predefined pointers (scene and equally distant pointers) which cannot be changed, and sliding pointers that are user defined (user adds them, deletes them etc.) which can have user comments. Every pointer will have a snapshot that will be shown to the user when he positions cursor over that pointer. The user will also be able to play the video from a selected pointer.

With nearly 100 mentoring organizations to choose from, there were 3050 students submitting 6338 proposals to this year’s Summer of Code. OhioLINK received 21 applications.

Google is sponsoring the Summer of Code, a program designed to introduce students to the world of Open Source Software Development. OhioLINK is pleased to participate again as a mentoring organization, furthering the development of information technology in academic libraries in Ohio and around the world. We have a page on our development site describing OhioLINK’s participation and projects; take a look, augment or add your own (feel free to read the project documentation through the ‘Wiki’ link above and suggest other ideas), and apply to participate. Questions about the program? Take a look at Google’s participant FAQ. Questions about the suggested projects or about OhioLINK? Contact Peter Murray.

The Ohio Library and Information Network, OhioLINK, is a consortium of Ohio’s college and university libraries and the State Library of Ohio. OhioLINK’s membership includes 17 public universities, 23 community/technical colleges, 44 private colleges and the State Library of Ohio. Funded by the Ohio Board of Regents, it serves more than 600,000 students, faculty, and staff at these 85 institutions with a consolidated catalog of library items across the state, a physical transport service that delivers those items to users within 48 hours, and cooperative buying of journals and research databases.

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