File Access Enhancements

The following enhancements have been made to IDL's file access capabilities in the IDL 6.1 release:

New IDL JPEG2000 File Format Support

IDL 6.1 includes support for the popular JPEG 2000 compression format, enabling researchers and software developers to achieve more efficient storage and handling of large images. JPEG 2000 is an open, international transmission standard and image compression format based on powerful wavelet technology. The format supports both lossless and lossy image compression, allowing you to store higher quality images in smaller files. JPEG 2000 support in IDL also provides unprecedented memory efficiency by letting you access, manipulate, and edit image data while the images are still in compressed form.

The new IDLffJPEG2000 object class provides access to the features of the JPEG 2000 file format for both input and output. For more information, see IDLffJPEG2000. Additionally, three new JPEG 2000 routines have been added to provide read, write and query functionality. For more information on these new routines, see QUERY_JPEG2000, READ_JPEG2000, and WRITE_JPEG2000.

New XML DOM Object Classes

IDL 6.1 supports reading, querying and writing XML files through a DOM (Document Object Model) interface. XML is eXtensible Markup Language, a popular storage standard used in sharing data across networks and the web. Support for reading XML through a SAX (Simple API for XML) interface was added in IDL 5.6. SAX can be preferable when parsing large files, while DOM allows complete file browsing and writing capabilities.

For more information on the new IDL object classes that provide access to an XML document via its document object model (DOM) see IDLffXMLDOM Classes.

Expanded DICOM Support

The new IDLffDicomEx object, available as an optional, add-on module to IDL, greatly expands IDL's DICOM capabilities. Previously, DICOM support was provided through the IDLffDICOM object. (See IDLffDICOM in the IDL Reference Guide for details.) For reference information, see the Medical Imaging in IDL manual. The IDLffDicomEx object offers the following enhancements over the IDLffDICOM object:

Ability to read from and write to DICOM files. Using the IDLffDicomEx object, you can read, clone, or create a new DICOM file. The IDLffDICOM object only supports reading DICOM files.

Ability to read and write both public and private attributes including sequences and sets of repeating tags within sequences (groups).

Ability to read and write compressed DICOM files on Windows and UNIX platforms.

Additional SOP class support.

Ability to copy DICOM attributes from on file to another, and output all tags in a DICOM file to an ASCII file or to an IDL structure.

Note

Revised Language Catalog System

The language catalog for widget labeling and message content has been revised to allow easier internationalization of IDL applications. The XML-based language catalogs are accessed using the new IDLffLangCat object. For more information, see IDLffLangCat.

CDF Library Upgrade

HDF5 Library Upgrade

IDL now uses the Hierarchical Data Format version 5 (HDF5) library version 5-1.6.1.

New Application User Directory Access

The new APP_USER_DIR function provides access to the IDL application user directory. The application user directory is a location where IDL, and applications written in IDL, can store user-specific data that will persist between IDL sessions. For example, the IDL iTools store user-specified preferences, styles, and macros in the application user directory.

The application user directory is created automatically by IDL as a subdirectory (named .idl) of the user's home directory. To prevent unrelated applications from encountering each other's files, the .idl directory is organized into subdirectories with names specified by the application author. APP_USER_DIR simplifies cross-platform application development by providing a well-defined location for IDL applications to store their resource files, regardless of the platform or version of IDL. The uniform organization it enforces is also a benefit for IDL users, since it makes it easier for them to understand the meaning and importance of the files found in their .idl directory.

A related function, APP_USER_DIR_QUERY, allows you to locate application user directories that match a specified set of search criteria. This can be useful when migrating user data created for one version of an IDL application to a new version of the application.

Enhancements to READ_TIFF

Three new keywords have been added to the READ_TIFF routine. The keywords are: DOT_RANGE, ICC_PROFILE, and PHOTOSHOP. See READ_TIFF for more details.

Enhancements to WRITE_TIFF

New keywords to the WRITE_TIFF routine include: CMYK, DESCRIPTION, DOCUMENT_NAME, DOT_RANGE, ICC_PROFILE, PHOTOSHOP, XPOSITION and YPOSITION. WRITE_TIFF now also includes in every TIFF file a DateTime tag, containing the file creation time. More notably, the new CMYK keyword supports publication-quality graphics using the cyan, magenta, yellow and black (CMYK) color model. Also, the XPOSITION and YPOSITION keywords have been added to match the TIFF 6.0 standard, specifying the location of data to be specified in raster or device space. See WRITE_TIFF for more details.

New QUERY_TIFF Info Structure Fields

Four new fields have been added to the Info structure returned by QUERY_TIFF. The fields are: DESCRIPTION, DOCUMENT_NAME, DATE_TIME and POSITION. See QUERY_TIFF for more details.

GEOTIFF Support for QUERY_TIFF

The new GEOTIFF keyword to QUERY_TIFF allows you to retrieve an anonymous structure containing the GeoTIFF tags and keys found in the file. GEOTIFF returns the same information as the GEOTIFF keyword to READ_TIFF, but avoids the overhead of reading in the entire image. For more information, see QUERY_TIFF.