Image Metadata

1. Image Metadata Summary of 4/18/99 NISO/DLF Image Metadata Meeting (http://www.niso.org/image.html) Howard Besser UCLA School of Education & Information http://www.sims.berkeley.edu/~howard

2. 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)

3. Break-out Groups • Characteristics and Features of Images • Image Production and Reformatting Features • Image Identification and Integrity

4. 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) What does this meetingdeal with?

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

6. Introductory Talk • Howard Besser’s introductory talk setting the agenda for the meeting (http://sunsite.berkeley.edu/Imaging/Databases/Metadata/niso-4-99/)

7. 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

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

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

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

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

12. 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)

13. Characteristics: Compression • Compression (M) • Sub–sampling (R) • Layering (M)

14. 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: Others...

15. 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)

16. 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.

17. 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

18. 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”

19. 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.

20. Image Metadata • Howard Besser • UCLA School of Education & Information • http://www.niso.org/image.html • http://sunsite.berkeley.edu/Imaging/Databases/Metadata/niso-4-99/ • http://www.sims.berkeley.edu/~howard • http://sunsite.Berkeley.EDU/Imaging/Databases/ #standards • http://sunsite.Berkeley.EDU/moa2/ • http://sunsite.Berkeley.EDU/Imaging/Databases/Longevity/ • http://www.nlc-bnc.ca/ifla/II/metadata.htm • http://purl.oclc.org/metadata/dublin_core/ • http://lcweb.loc.gov/ead/