Aware JPEG2000 for Digital Archives

Standards-Compliant Software Tools to Build Client/Server Image Viewing Applications

Preserving rare documents and photographs presents certain challenges for which JPEG 2000 is well suited. Archivists must balance the need for providing public access to special collections while preserving them for future generations.

JPEG 2000 is an international standard (ISO 15444) for image compression that uses a wavelet technique to overcome the image quality and functional limitations of current image formats. JPEG 2000 provides a lossless compression option for preservation of digital images.

Navigation and display of large archive quality images on a remote client becomes very efficient using this standard based technology.

Key Features

  • JPEG 2000 file standard includes rich support for metadata
  • Easy to integrate
  • Runs on Windows, Solaris, or Linux servers
  • All navigation, workflow, and web page design is open and customizable
  • Rich metadata support through JP2 or JPX file formats
  • Metadata editor
  • Simplified repository management and reduced storage requirements
  • Resolution and quality scalability
  • Lossless compression and lossy decompression
  • Progressive display
  • Tiling
  • Region of interest encoding

JPEG 2000 offers several benefits that make it an ideal solution for creating digital archives:

JPEG 2000 Facilitates Collaboration

Collaboration is fundamental to the mission of most archives. They may wish to transfer batches of image files and metadata to third parties in order to share responsibility for long-term custody or to build union repositories for access. Many digitization projects have been based on digitization at individual institutions for contribution to a “union” site.

The ISO standard-compliant nature of JPEG 2000 and its embedded support for multiple types of metadata helps to ensure that, when used to create digital archives, the content outlives the systems that created it.

  • For digital archives, the value of JPEG 2000 is in its “openness.”
  • The image objects are self-contained for the long term.
  • Interoperability of the data can be assured as long as each system is compliant with the standard.
  • Implementations and tools to support the standard will be widespread.
  • Eliminates the need and expense of proprietary compression.
5000 & 7000 pixel image compressed 20:1.By encoding it in tiles of 512 x 512, and five resolution layers per tile, this very large image can be efficiently decoded and managed for viewing.

5000 & 7000 pixel image compressed 20:1.By encoding it in tiles of 512 x 512, and five resolution layers per tile, this very large image can be efficiently decoded and managed for viewing.

Rich Support for Metadata

The comprehensive and flexible nature of metadata support within JPEG 2000 makes it ideal for digital archives.

Part 1 baseline JPEG 2000 supports embedded metadata in the following ways:

  1. Inclusion of comments directly in the codestream: The comments can be either ISO Latin 15 text or binary in format. The length of each text string can be up to 64 kbytes and the text strings can be placed in the main file header or the header for each tile if the image is tiled
  2. JP2 File Format: JP2 is an optional file format that may be used to wrap JPEG 2000 codestreams. The file format includes capabilities to specify the colorspace of the image, alpha channel information, and large amounts of metadata. Multiple JPEG 2000 codestreams can be wrapped into a single JP2 file. All information in a JP2 file is included in entities called “boxes”. For example, a specific box type is used to include a JPEG 2000 codestream, a different one is used to include colorspace information.

The JP2 file format defines the following box types for the inclusion of metadata into the JP2 file:

  • Intellectual Property Box – Used for carrying intellectual property
  • rights information about the image(s) in the file.
  • XML Box – Used for vendor specific information in XML format.
  • URL Box – Used for including an URL that can be used by an application to acquire more information about the associated image or vendor.
  • UUID Box – Used for any other information not covered by above metadata boxes.

The UUID box is the most versatile metadata mechanism. It allows the user or application to associate any type of information with the image file in a specific place. Decoders that are designed to read JP2 files with this information included can extract it easily, while others can disregard it completely.
https://www.aware.com/imaging/images/medford_12_r2_c2.gif

Losslessly compressed image (Ratio of 2:1) Whole image encoded in 5 quality layers. The quality layers within each tile can be individually decoded and represent rations of 12:1, 20:1, 30:1, and 50:1.

Losslessly compressed image (Ratio of 2:1) Whole image encoded in 5 quality layers. The quality layers within each tile can be individually decoded and represent rations of 12:1, 20:1, 30:1, and 50:1.

Scalability

The JPEG 2000 standard was designed to support the efficient electronic dissemination of digital documents and images to multiple end users. A properly designed system can leverage the encoding and decoding options of JPEG 2000 to provide end users with Just Enough Quality delivered Just in Time.

Resolution Scalability

JPEG 2000 allows reduced resolution images to be quickly and efficiently extracted from a compressed file. This capability is useful for generating index or catalog pages with thumbnails of each image. With JPEG 2000, sub resolution images of various size can be extracted from the single compressed file and do not need to be stored separately.

Quality Scalability

JPEG 2000 also allows reduced quality images to be extracted from a compressed file, producing images with higher effective compression ratios optimized for specific workflows.

Lossless Compression and Lossy Decompression

This implementation of quality scalability elegantly supports remote viewing and access of large losslessly compressed image files. For archival and reference purposes, a lossless image at 2:1 compression can be stored on the server. From this master file, a medium quality image at 30:1 compression can be extracted and transmitted for browsing, and a high quality image at 10:1 compression can be extracted and viewed for most research. JPEG 2000 allows the more highly compressed images to be quickly extracted from the single master file. With the layered file format, only the additional layers must be transmitted to progress to a higher quality image.

Progressive Display

JPEG 2000’s progressive transmission format displays a low resolution version of an image after only a small portion of the file has been received. As more data arrives, the display is progressively refined until the full resolution image is shown. This feature allows a user to quickly orient themselves to an image, reducing the time spent waiting for data to arrive.

User interface for the Aware large image encoder/decoder tool (source code included) - This shows Resolution 2 of 5 for each tile. Those tiles bounded by red overlay have yet to be fully decoded.

User interface for the Aware large image encoder/decoder tool (source code included) – This shows Resolution 2 of 5 for each tile. Those tiles bounded by red overlay have yet to be fully decoded.

Rich Support for Metadata

The comprehensive and flexible nature of metadata support within JPEG 2000 makes it ideal for digital archives.
Part 1 baseline JPEG 2000 supports embedded metadata in the following ways:

  1. Inclusion of comments directly in the codestream: The comments can be either ISO Latin 15 text or binary in format. The length of each text string can be up to 64 kbytes and the text strings can be placed in the main file header or the header for each tile if the image is tiled
  2. JP2 File Format: JP2 is an optional file format that may be used to wrap JPEG 2000 codestreams. The file format includes capabilities to specify the colorspace of the image, alpha channel information, and large amounts of metadata. Multiple JPEG 2000 codestreams can be wrapped into a single JP2 file. All information in a JP2 file is included in entities called “boxes”. For example, a specific box type is used to include a JPEG 2000 codestream, a different one is used to include colorspace information.

The JP2 file format defines the following box types for the inclusion of metadata into the JP2 file:

  • Intellectual Property Box – Used for carrying intellectual property rights information about the image(s) in the file.
  • XML Box – Used for vendor specific information in XML format.
  • URL Box – Used for including an URL that can be used by an application to acquire more information about the associated image or vendor.
  • UUID Box – Used for any other information not covered by above metadata boxes.

The UUID box is the most versatile metadata mechanism. It allows the user or application to associate any type of information with the image file in a specific place. Decoders that are designed to read JP2 files with this information included can extract it easily, while others can disregard it completely.