170 Appendix A
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Low-Level Metadata Interface
Two MediaScript objects provide support for metadata: The Media object and the
_MR_Metadata object.
The Media object provides support for loading and saving metadata along with the image
contents.
The _MR_Metadata object provides support for loading and merging just the metadata
contained within the files, without loading the image data. This allows the scripter to
modify the metadata within compressed files without decompressing and recompressing
the image data.
The Media Object
The load command of the Media object will load and attach Exif, IPTC, and XMP metadata
if the loadMetadata parameter to the load command is specified as true. For example:
var image = new Media();
image.load(name @ “myimage.jpg”, loadMetadata @ true);
This constructs an XML document for any Exif, IPTC, or XMP metadata contained in the
file and attach it to the Media object. This metadata can be accessed by the scripter using
the getMetadata command of the Media object.
var metaDoc = image.getMetadata(“IPTC”);
This metadata document can be processed and edited. To modify the metadata attached to
the image, use the setMetadata method:
image.setMetadata(“Exif”, myExifData);
Finally, use the save method to save any metadata attached to the document unless the
SaveMetadata parameter is set to false.
image.save(type @ “jpeg”);
The metadata names for use with the getMetadata and setMetadata methods are
“Exif”, “IPTC”, and “XMP” for the Exif, IPTC, and XMP metadata documents, respectively.
These names are case-sensitive.
NOTE A save() function will embed a color profile for a color profile-supporting format without
explicitly setting saveMetadata to “true” only when CMYK data is present.
The _MR_Metadata Object
The _MR_Metadata object supports extracting metadata from supported file formats
without loading the image data. It also supports merging new metadata into existing files
without the need to interpret or decompress the image data. The _MR_Metadata object has
two methods: save, and load. In addition, the _MR_Metadata object can be used as the
MediaScript response object allowing the script to stream back a file with modified
metadata.
