Artwork Metadata

At the end of the day, digital artworks are files that can exist on the web as well as in offline storage. Therefore, before minting the NFT, it's worthwhile to take care of the metadata.

If someone changes the metadata of the artwork, it means that the file is modified, and it will have a different checksum. Therefore, the NFT should reference as complete a file as possible for double security against fraudsters.

Image

At Silvermind we use fields from different standards, but mainly we rely on XMP-dc, XMP-xmpRights. Exif is only used to the minimal extent, because it's not intended for carrying the semantic information.

XMP-dc:contributor

An entity responsible for making contributions to the resource. Examples of a contributor include a person, an organization, or a service. Typically, the name of a contributor should be used to indicate the entity. XMP usage is a list of contributors. These contributors should not include those listed in XMP-dc:creator.

XMP-dc:coverage

The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant. XMP usage is the extent or scope of the resource.

XMP-dc:creator

An entity primarily responsible for making the resource. Examples of a creator include a person, an organization, or a service. Typically, the name of a creator should be used to indicate the entity. XMP usage is a list of creators. Entities should be listed in order of decreasing precedence, if such order is significant.

Silvermind uses this field to define the artist. There's a separate Exif field Artist for that as well.

XMP-dc:date

A point or period of time associated with an event in the life cycle of the resource.

Silvermind suggests to put the date of publication of the NFT.

XMP-dc:description

An account of the resource. XMP usage is a list of textual descriptions of the content of the resource, given in various languages.

The description of the image should normally coincide with the description of NFT. However, people tend to put more information there, because marketplaces will show the description for sure. Moreover, the NFT description should be in Markdown syntax, this is the way to structure it minimally and have links. Marketplaces normally support this.

XMP-dc:format

The file format, physical medium, or dimensions of the resource. Examples of dimensions include size and duration. Recommended best practice is to use a controlled vocabulary such as the list of Internet Media Types [MIME]. XMP usage is a MIME type. Dimensions would be stored using a media-specific property, beyond the scope of this document.

XMP-dc:identifier

An unambiguous reference to the resource within a given context. Recommended best practice is to identify the resource by means of a string conforming to a formal identification system.

Silvermind uses this field to reference the NFT using a URN notation: urn:<blockchain>:<collectionid>:<tokenid>, for instance urn:ethereum:0x123abcdef:2

This field is probably the most important one, as it points to the NFT itself. Therefore we have a bidirectional relationship between the artwork and the NFT.

XMP-dc:language

A language of the resource. XMP usage is a list of languages used in the content of the resource.

XMP-dc:publisher

An entity responsible for making the resource available. Examples of a publisher include a person, an organization, or a service. Typically, the name of a publisher should be used to indicate the entity. XMP usage is a list of publishers.

Silvermind will default to silvermind.art in this field when the minting is performed using Silvermind.

XMP-dc:relation

A related resource. Recommended best practice is to identify the related resource by means of a string conforming to a formal identification system. XMP usage is a list of related resources.

XMP-dc:rights

Information about rights held in and over the resource. Typically, rights information includes a statement about various property rights associated with the resource, including intellectual property rights. XMP usage is a list of informal rights statements, given in various languages.

Silvermind suggests to put copyright (Exif field Copyright), a short info about the license or usage terms (derived from XMP-xmlRights:UsageTerms), and a disclaimer or a legal notice.

XMP-dc:source

A related resource from which the described resource is derived. The described resource may be derived from the related resource in whole or in part. Recommended best practice is to identify the related resource by means of a string conforming to a formal identification system.

XMP-dc:subject

The topic of the resource. Typically, the subject will be represented using keywords, key phrases, or classification codes. Recommended best practice is to use a controlled vocabulary. To describe the spatial or temporal topic of the resource, use the XMP-dc:coverage field. XMP usage is a list of descriptive phrases or keywords that specify the content of the resource (what's visible in the picture).

XMP-dc:title

A name given to the resource. Typically, a title will be a name by which the resource is formally known. XMP usage is a title or name, given in various languages. Normally this should coincide with the Exif field ImageDescription.

The title of the image should normally coincide with the name of NFT.

XMP-dc:type

The nature or genre of the resource. Recommended best practice is to use a controlled vocabulary such as the DCMI Type Vocabulary. To describe the file format, physical medium, or dimensions of the resource, use the XMP-dc:format field. For this specific case it is Image type.

XMP-xmpRights:Certificate

A web URL for a rights management certificate.

Silvermind will put the IPFS URI to the certificate of authenticity (e-autograph) in this field.

XMP-xmpRights:Marked

When true, indicates that this is a rights-managed resource. When false, indicates that this is a public-domain resource. If ommited - the state is unknown (normally it must be assumed that it's not a public domain).

For example, when creative commons licenses are used, Silvermind will put false when the CC0 is used, and true with other licenses.

XMP-xmpRights:Owner

A list of legal owners of the resource. It should be names that are mentioned in the Exif field Copyright.

XMP-xmpRights:UsageTerms

A collection of text instructions on how a resource can be legally used, given in a variety of languages. It shouldn't contain the reference to the license, instead the license should be verbatim. When there's a license referred in XMP-xmpRights:WebStatement then we can mention the licensing and usage terms only briefly, as we did in XMP-dc:rights.

XMP-xmpRights:WebStatement

A Web URL for a statement of the ownership and usage rights for this resource.

Normally one would point to a Web page, where, for instance, creative commons license is nicely presented. This wouldn't compatible with Web3 ideology. Silvermind would suggest to take the copy of the license and use IPFS reference here.

Exif:Artist (not Exif:Photographer)

Same as XMP-dc:Creator. Even if the image is actually a photo we favour Exif:Artist.

Exif:Copyright

Copyright information, which points to the owners and the relevant year(s).

Exif:ImageDescription (not Exif:Title)

It's a short description of the image, so logically it must match the XMP-dc:title. It's tempting to use XMP-dc:description here, but the semantics is somewhat mixed up, therefore Silvermind suggest to stick to XMP-dc:title. XP:Title is not standard, so we sacrifice it in favor of Exif:ImageDescription.

Exif:CreateDate (aka Exif:DateTimeDigitized), Exif:DateTimeOriginal

It's known as DateTimeDigitized, so basically it's the timesamp when the digital asset is born. If during the modification we see that Exif:DateTimeOriginal happens to be later than Exif:DateTimeDigitized then we'll make them both the same, otherwise we keep the original as it was. The timestamp should be written in UTC timezone.

Normally, when we talk about a purely digital art, the "original" and "digitized" timestamps are the same. In photography, though they may differ.

Exif:ModifyDate (aka Exif:DateTime)

It's known as DateTime, so this is the last modification timestamp. The timestamp should be written in UTC timezone.

Silvermind suggest to use the timestamp of the e-autograph, as the autograph should be the last modification by the author, before parting with the artwork.