JPEG2000-hul Module

1 Introduction

The JPEG2000-hul module recognizes and validates the JPEG 2000 (ISO/IEC 15444) format, a digital representation format for lossy or losslessly-compressed bi-tonal, grayscale, palette color, and continuous color still image data.

The module is invoked by the:

jhove ... -m JPEG2000-hul ...

command line option.

2 Coverage

The JPEG2000-hul module recognizes and validates the following public profiles:

  • JP2 profile (ISO/IEC 15444-1:2000/ITU-T Rec. T.800 (2002)) [JP2, ITU-T T.800]
  • JPX profile (ISO/IEC 15444-2:2004) [JPX]

3 Well-Formedness

The following criteria must be met by a JPEG 2000 object for JHOVE to consider it well-formed:

  • The required Signature and File Type box structures are the first two boxes in the file
  • All boxes required by a given profile exist in the file
  • All box structures are well-formed (a four byte unsigned integer Box Length, followed by a four byte unsigned integer Box type, followed by a eight byte unsigned integer Box Length, followed by the Box Contents)
  • No data exist before the first byte of the first box or after the last byte of the last box

4 Validity

The following criteria must be met by a JPEG 2000 file for JHOVE to consider it valid:

  • The file is well-formed

5 Representation Information

The MIME type for the JP2 profile is reported as: image/jp2; for the JPX profile: image/jpx.

In addition to the standard JHOVE representation information, the following JPEG 2000-specific properties are reported:

  • Property “JPEG2000Metadata” of type PROPERTY and arity ARRAY
    • Properties capturing the technical attributes of the JPEG 2000 image from all boxes

Image technical properties are reported in terms of the NISO Z39.87 data dictionary.

5.1 Profiles

  • JP2

    JP2 is the file format defined by ISO/IEC 15444-1:2000/ITU-T Rec. T.800 (2002) [JP2, ITU-T T.800]. The JP2 profile provides a baseline format for the exchange of still image data using a limited range of colorspaces.

    Profile requirements include:

    • The File Type box BR field is “jp2 “ (note the trailing SPACE character)
    • JP2 Header superbox precedes any code stream or Label boxes and includes Image Header and Colour Specification boxes
    • The Colour Specification box APPROX field is 0 and the METH field is either 1 or 2

  • JPX

    JPX is the file format defined by ISO/IEC 15444-2:2004 [JPX]. The JPX profile provides extensions to JP2 that allow additional colorspaces, the specification of opacity, standardized metadata, multiple image data streams, and more non-contiguous internal organization of the image data.

    Profile requirements include:

    • The File Type box BR field is “jpx “ (note the trailing SPACE character)
    • Reader Requirements box immediately follows the File Type box
    • JP2 Header superbox includes Image Header and Colour Specification boxes
    • The Colour Specification box APPROX field is non-zero

6 Additional Module Properties

  • Nominal file extension: .jp2 (for JP2 profile) [RFC 3745]
  • Nominal file extension: .jpf (for JPX profile)
  • Alternative file extension: .jpx (for JPX profile)