JPEG-hul Module

1 Introduction

The JPEG-hul module recognizes and validates the JPEG format.

The module is invoked by the:

jhove ... -m JPEG-hul ...
command line option.

Formally, JPEG refers to a format for compressed images created by the Joint Photographic Experts Group and codified in ISO/IEC 10918-1 [JPEG]. In 1992 C-Cube Microsystems published a specification for an interchange file format called JFIF (JPEG File Interchange Format) that encapsulates the JPEG data stream [JFIF]. What most people refer to as "JPEG" files are more properly JFIF files. However, many existing "JPEG" files do in fact contain only the "raw" JPEG data stream.

2 Coverage

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

3 Well-Formedness

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

JHOVE uses the JPEG-LS algorithm for recognizing the end of a data stream, looking for a byte of 0xFF followed by a byte in the range 0X80 through 0XFE. The standard JPEG algorithm looks for a byte of 0XFF followed by any byte which is not 0 or 0xFF. Since all valid markers in existing versions of JPEG are in the range 0X80 through 0XFE, this algorithm works correctly for both JPEG and JPEG-LS.

4 Validity

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

A file which consists of a JPEG data stream, but does not contain the required segments for a JFIF, SPIFF, Exif, JTIP, or JPEG-LS file is considered well-formed but not valid.

5 Representation Information

The MIME type is reported as: image/jpeg

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

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

5.1 Profiles

6 Additional Module Properties

Copyright 2004-2005 by JSTOR and the President and Fellows of Harvard College. Used by permission.
Last updated 2005-05-26