Social Media systems:
metadata test procedure

The Goal

Metadata is embedded into image files to keep the metadata sticking to the picture data for the image's lifetime, this is outlined as a major goal of the Embedded Metadata Manifesto.

The goal of this Social Media Photo Metadata test was to find out if embedded metadata is stripped-off while an image goes through a Social Media system - undermining the goal of the Embedded Metadata Manifesto this way.

Test Workflow

  • Starting point was an image file with embedded metadata, e.g. this IPTC metadata reference picture. It includes Exif metadata in an Exif header and IPTC metadata in an IIM header and an XMP header.
  • This image file was uploaded to the Social Media system as outlined by the system.
  • On the user interface the required option was selected to display the uploaded photo.
  • The first test was:
    Are any of the embedded metadata fields of the image file shown by the web user interface?
    If yes, it was checked if the field values are displayed correctly. And it was checked if a label of a shown field reflects the same semantics as the corresponding IPTC or Exif metadata field.
    Find the results of this test in the "Displays correctly" column of the results grid and find our ranking criteria in the table below.
  • The second test was:
    If metadata fields were displayed did this include the most relevant metadata fields for describing the image and claiming the copyright on this image: Caption, Creator, Copyright Notice or Creditline, the 4C columns.
    Find the results in the "Displays 4Cs" column of the results grid and find our ranking criteria in the table below.
  • The third test was:
    A web browser command was executed to save the image file - in the largest available size! - to a local computer (using something like "Save Image As ...").
    If this was possible then this saved image file was checked for the existence of embedded metadata:
    - did Exif metadata exist in the Exif header
    - did IPTC metadata exist in the IIM header
    - did IPTC metadata exist in the XMP header.
    Find the results in the "Save As embedded?" column of the results grid and find our ranking criteria in the table below.
  • The fourth test was:
    The previously uploaded test image was downloaded by the system's user interface (e.g. a Download button or menu item). If this feature was provided the downloaded image file was checked for the existence of embedded metadata:
    - did Exif metadata exist in the Exif header
    - did IPTC metadata exist in the IIM header
    - did IPTC metadata exist in the XMP header?

    Find the results in the "Download embedded?" column of the results grid and find our ranking criteria in the table below.

Ranking of the Test Results

The columns of the ranking table below refer to the four tests described above.
The rows of the table below refer to the three colours the test result icons can show.

The label below the coloured dot indicates the referenced metadata or image field header to which this dot applies:

  • IPTC: any IPTC photo metadata field
  • IPTC IIM: IPTC photo metadata fields in the IPTC IIM format for saving metadata in an image file header
  • IPTC XMP: IPTC photo metadata fields in the XMP format for saving metadata in an image file header
  • Exif: any Exif photo metadata field in the format of the Exif headers for saving metadata in an image file.

(Find more about the specifications of these metadata and formats in the References section at the bottom of this page.)

 

Test 1:
Displays
correctly?

Test 2:
Displays
4Cs?

Test 3:
SaveAs
embedded?

Test 4:
Download
embedded?

Red dot Not all displayed field values appear as embedded or field labels do not align with the specification
None of the 4Cs (Copyright, Credit, Creator and Caption) are displayed
No metadata are embedded at all or only a minority; or none of the embedded field values are either from the original file or from what has been edited online (if this feature is available)

No metadata are embedded at all or only a minority; or none of the embedded field values are either from the original file or from what has been edited online (if this feature is available)
Yellow dot N/A 1 to 3 of the 4Cs (Copyright, Credit, Creator and Caption) are displayed
A majority of embedded field values are either from the original file or from what has been edited online (if this feature is available)
A majority of embedded field values are either from the original file or from what has been edited online (if this feature is available)
Green dot All displayed field values appear as embedded and the field labels do align with the specification
Copyright and/or Credit and Creator and Caption are displayed
All embedded field values are either from the original file or from what has been edited online (if this feature is available)
All embedded field values are either from the original file or from what has been edited online (if this feature is available)
Grey
dot
This icon stands for: it was not possible to test this feature. It is used for e.g. the result from "Displays correctly" if no metadata are displayed at all.

Note

The results for IPTC and Exif metadata fields are noted separately.

 

The results for IPTC metadata fields in IIM and XMP headers and Exif metadata fields in the Exif header are noted separately.

The results for IPTC metadata fields in IIM and XMP headers and Exif metadata fields in the Exif header are noted separately.

 

Who Tested?

Contributors to the photo metadata survey of controlledvocabulary.com and members of the Photo Metadata Working Group of the IPTC.

What are the results of the tests?

See them in this test results grid >>

References

Specification document of the IPTC Photo Metadata fields as of 2010:
www.iptc.org/std/photometadata/specification/IPTC-PhotoMetadata-201007_1.pdf

Specification document of the IPTC IIM metadata format as of 1997:
www.iptc.org/std/IIM/4.1/specification/IIMV4.1.pdf

Specification documents of the XMP metadata format as published by Adobe in 2012:
find them on the page www.adobe.com/devnet/xmp.html

Specification document of the Exif metadata fields and format as published by CIPA in 2010:
www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2010_E.pdf