Image Metadata Summary of 4/18/99 NISO/DLF Image Metadata Meeting ( Howard Besser UCLA School of Education & Information

Meeting Goal examine technical information needed to manage and use digital still images that reproduce a variety of pictures, documents and artifact, which might include: –Metadata fields –Rules for Field Contents (authority control) –Core set of necessary fields –Syntax for expressing fields and contents (headers)

Break-out Groups  Characteristics and Features of Images  Image Production and Reformatting Features  Image Identification and Integrity

What does this meeting deal with? In Scope  still, bit-mapped pictorial images  scanned/reformatted images (+ born digital) Out of Scope  vector images  moving images  images of OCR-able text  structural and hierarchical relationships between images  rights management, terms of use  (authenticity/security)

Focus on Metadata that may prove helpful for  management  use  preservation ...

Introductory Talk Howard Besser’s introductory talk setting the agenda for the meeting (

Agreements a preliminary list of technical metadata elements the need for a categorization of elements as mandatory or optional the need for metadata to help evaluate the utility of an image for a particular application or use using industry standard metrics for assessing images where they existed (tone, color, icc profiles,).v the need for methods of pointing at external test charts the importance of mechanisms for referring to external metadata file the need for image specific metadata and methods for creating this metadata the importance of persistence of metadata through transformations of an image the fact that the metadata assigned an item depended on the metadata creators' definition of the work the desirability of solutions devised to work in a broad array of contexts

Break-out Groups: Work Done  Characteristics and Features of Images  Image Production and Reformatting Features  Image Identification and Integrity

Characteristics and Features of Images  Format issues  Resolution issues  Color issues  Compression stuff  Other characteristics  Characteristics passed on to other groups  Guiding Principles

Characteristics: Format issues MIME type (M) File Format (M) File Size (O) Class ID/ ‘Genotype’ (Desirable)

Characteristics: Resolution issues Spatial resolution at capture (M) Orientation (M) Pixel array size/count (M)

Characteristics: Color issues Tonal resolution (M) Channels and Layers (M) Byte Order (M) Photometric interpretation (M) Colour space (M) Colour management (M) Gamma correction (O) White point/ black point (O)

Characteristics: Compression Compression (M) Sub–sampling (R) Layering (M)

Characteristics: Others... Watermark (R) Encryption (R) External metadata (R) Thumbnail (O) ( Unique ?) Identifier (R) Test charts (O) Platen colour (O) Fill or padding (R) Image quality (O)

Characteristics: Passed to other groups Date & Time ( to both ) Image Enhancement ( to both ) Audit Trail ( to both ) Dimensions of original object ( ‘Descriptive’ ) Reflective/ Transmission ( to Production ) Lamp/Sensor characteristics ( to Production ) Identification ( to Identification )

Characteristics: Guiding principles Metadata that is not directly ‘actionable’ should not necessarily be in the file header Metadata should have a long–term utility We should specifically deal with the image at hand We should be aware of the cost of omission Those elements described as (M) are only mandatory if not already represented within the file format in question.

Image Production and Reformatting Features  Need to document the intent of the reformatting  Document what you do  Use full-text field to include all the attributes of the scanning process  Include a target with the digital image

Image Identification and Integrity Administrative and Descriptive metadata are hard to think about separately The identification and integrity problems for images are often the same as other digital files, but the solutions are not How to handle future situations when home digital camera images eventually enter archives? Often bad image metadata is good Verification needs to deal with the digital object, not a particular file format representation of that object Need a vocabular for expressing generational relationships (Image Families) “When” is easy compared to “Who”, “Why”, and “What”

Action Items Publishing an expanded/edited set of metadata elements with examples. Articulating what tools need to be developed to assess how well an image was made. Exploring the viability of creating an integrated test chart. Making an inventory of existing tools and metadata standards. Developing guidelines and a template for the kind of data that should go into a project description. Drafting a canonical image format that will express equivalence of data that may have been stored in multiple image formats. Scoping the effort involved in defining a vocabulary to express the relationships between images.

Image Metadata Howard Besser UCLA School of Education & Information #standards