Image Description

The Image type is defined in ActivityStreams Vocabulary.

In this support table, we only consider how the image description, commonly called AltText is handled. Image descriptions are important from an accessibility standpoint, see WCAG 2.2. Text Alternatives.

It seems that certain implementations, e.g. firefish, store the image description on a per image URL basis and not for every instance of an image reference.

Examples

Example 1

activity

{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://sharkey/users/a0tso0t2npkb0001"
  ],
  "id": "http://pasture-one-actor/actor/JrhVwvb17Vg",
  "published": "2024-11-20T18:44:15Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://sharkey/users/a0tso0t2npkb0001"
    ],
    "id": "http://pasture-one-actor/actor/_uPP66psh7Q",
    "published": "2024-11-20T18:44:15Z",
    "content": "no description",
    "attachment": {
      "type": "Document",
      "url": "http://pasture-one-actor/images/100.png"
    }
  }
}

sharkey

{
  "id": "a0tsr4m09ndr0010",
  "uri": "http://pasture-one-actor/actor/_uPP66psh7Q",
  "url": "http://pasture-one-actor/actor/_uPP66psh7Q",
  "account": {
    "id": "a0tspttm9ndr0002",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "fqn": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": false,
    "created_at": "2024-11-20T18:43:14.362Z",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 28,
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "uri": "http://pasture-one-actor/actor",
    "avatar": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "avatar_static": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "header": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "header_static": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "emojis": [],
    "moved": null,
    "fields": [],
    "bot": false,
    "discoverable": true
  },
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "content": "<p><span>no description</span></p>",
  "content_type": "text/x.misskeymarkdown",
  "text": "no description",
  "created_at": "2024-11-20T18:44:15.000Z",
  "emojis": [],
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "reblogged": false,
  "favourited": false,
  "muted": false,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "media_attachments": [
    {
      "id": "a0tsr5eo9ndr000z",
      "type": "image",
      "url": "http://pasture-one-actor/images/100.png",
      "remote_url": "http://pasture-one-actor/images/100.png",
      "preview_url": "http://pasture-one-actor/images/100.png",
      "text_url": "http://pasture-one-actor/images/100.png",
      "meta": {
        "width": 40,
        "height": 40
      },
      "description": null,
      "blurhash": "e09}cN,?fQ,?fQ,?jtfQjtfQfQfQfQfQfQ,?jtfQjtfQfQfQfQfQfQ"
    }
  ],
  "mentions": [],
  "tags": [],
  "card": null,
  "poll": null,
  "application": null,
  "language": null,
  "pinned": false,
  "reactions": [],
  "emoji_reactions": [],
  "bookmarked": false,
  "quote": null,
  "edited_at": null
}

Example 2

activity

{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://sharkey/users/a0tso0t2npkb0001"
  ],
  "id": "http://pasture-one-actor/actor/rn4h2GS0TTg",
  "published": "2024-11-20T18:44:16Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://sharkey/users/a0tso0t2npkb0001"
    ],
    "id": "http://pasture-one-actor/actor/zmyVSJ_fcnI",
    "published": "2024-11-20T18:44:16Z",
    "content": "text",
    "attachment": {
      "type": "Document",
      "url": "http://pasture-one-actor/images/100.png",
      "name": "name",
      "summary": "summary",
      "content": "content"
    }
  }
}

sharkey

{
  "id": "a0tsr5ds9ndr0012",
  "uri": "http://pasture-one-actor/actor/zmyVSJ_fcnI",
  "url": "http://pasture-one-actor/actor/zmyVSJ_fcnI",
  "account": {
    "id": "a0tspttm9ndr0002",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "fqn": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": false,
    "created_at": "2024-11-20T18:43:14.362Z",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 29,
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "uri": "http://pasture-one-actor/actor",
    "avatar": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "avatar_static": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "header": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "header_static": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "emojis": [],
    "moved": null,
    "fields": [],
    "bot": false,
    "discoverable": true
  },
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "content": "<p><span>text</span></p>",
  "content_type": "text/x.misskeymarkdown",
  "text": "text",
  "created_at": "2024-11-20T18:44:16.000Z",
  "emojis": [],
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "reblogged": false,
  "favourited": false,
  "muted": false,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "media_attachments": [
    {
      "id": "a0tsr61r9ndr0011",
      "type": "image",
      "url": "http://pasture-one-actor/images/100.png",
      "remote_url": "http://pasture-one-actor/images/100.png",
      "preview_url": "http://pasture-one-actor/images/100.png",
      "text_url": "http://pasture-one-actor/images/100.png",
      "meta": {
        "width": 40,
        "height": 40
      },
      "description": "name",
      "blurhash": "e0A+OU=$fQ=$fQ=$j[fQj[fQfQfQfQfQfQ=$j[fQj[fQfQfQfQfQfQ"
    }
  ],
  "mentions": [],
  "tags": [],
  "card": null,
  "poll": null,
  "application": null,
  "language": null,
  "pinned": false,
  "reactions": [],
  "emoji_reactions": [],
  "bookmarked": false,
  "quote": null,
  "edited_at": null
}

Example 3

activity

{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://sharkey/users/a0tso0t2npkb0001"
  ],
  "id": "http://pasture-one-actor/actor/lYttia38Esw",
  "published": "2024-11-20T18:44:17Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://sharkey/users/a0tso0t2npkb0001"
    ],
    "id": "http://pasture-one-actor/actor/Qzik7BY4O5k",
    "published": "2024-11-20T18:44:17Z",
    "content": "text",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture-one-actor/assets/FediverseLogo.png",
        "name": "name",
        "imageType": "image/jpeg"
      }
    ]
  }
}

sharkey

{
  "id": "a0tsr65k9ndr0014",
  "uri": "http://pasture-one-actor/actor/Qzik7BY4O5k",
  "url": "http://pasture-one-actor/actor/Qzik7BY4O5k",
  "account": {
    "id": "a0tspttm9ndr0002",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "fqn": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": false,
    "created_at": "2024-11-20T18:43:14.362Z",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 30,
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "uri": "http://pasture-one-actor/actor",
    "avatar": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "avatar_static": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "header": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "header_static": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "emojis": [],
    "moved": null,
    "fields": [],
    "bot": false,
    "discoverable": true
  },
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "content": "<p><span>text</span></p>",
  "content_type": "text/x.misskeymarkdown",
  "text": "text",
  "created_at": "2024-11-20T18:44:17.000Z",
  "emojis": [],
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "reblogged": false,
  "favourited": false,
  "muted": false,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "media_attachments": [
    {
      "id": "a0tsr6po9ndr0013",
      "type": "image",
      "url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "preview_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "text_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "meta": {
        "width": 1548,
        "height": 1548
      },
      "description": "name",
      "blurhash": "eQE_?c.}4.YJM^}fi{EVw[xu9JK[M~xI-T9+TJRPX2$$E]NFo}j1tO"
    }
  ],
  "mentions": [],
  "tags": [],
  "card": null,
  "poll": null,
  "application": null,
  "language": null,
  "pinned": false,
  "reactions": [],
  "emoji_reactions": [],
  "bookmarked": false,
  "quote": null,
  "edited_at": null
}

Example 4

activity

{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://sharkey/users/a0tso0t2npkb0001"
  ],
  "id": "http://pasture-one-actor/actor/cR1ngyKwbRw",
  "published": "2024-11-20T18:44:18Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://sharkey/users/a0tso0t2npkb0001"
    ],
    "id": "http://pasture-one-actor/actor/OAl_Sz9IfOw",
    "published": "2024-11-20T18:44:18Z",
    "content": "no comment in attachment",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture-one-actor/assets/FediverseLogo.png"
      }
    ]
  }
}

sharkey

{
  "id": "a0tsr6xc9ndr0015",
  "uri": "http://pasture-one-actor/actor/OAl_Sz9IfOw",
  "url": "http://pasture-one-actor/actor/OAl_Sz9IfOw",
  "account": {
    "id": "a0tspttm9ndr0002",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "fqn": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": false,
    "created_at": "2024-11-20T18:43:14.362Z",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 31,
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "uri": "http://pasture-one-actor/actor",
    "avatar": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "avatar_static": "https://dev.joinsharkey.org/static-assets/avatar.png",
    "header": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "header_static": "https://dev.joinsharkey.org/static-assets/transparent.png",
    "emojis": [],
    "moved": null,
    "fields": [],
    "bot": false,
    "discoverable": true
  },
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "content": "<p><span>no comment in attachment</span></p>",
  "content_type": "text/x.misskeymarkdown",
  "text": "no comment in attachment",
  "created_at": "2024-11-20T18:44:18.000Z",
  "emojis": [],
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "reblogged": false,
  "favourited": false,
  "muted": false,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "media_attachments": [
    {
      "id": "a0tsr6po9ndr0013",
      "type": "image",
      "url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "preview_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "text_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "meta": {
        "width": 1548,
        "height": 1548
      },
      "description": "name",
      "blurhash": "eQE_?c.}4.YJM^}fi{EVw[xu9JK[M~xI-T9+TJRPX2$$E]NFo}j1tO"
    }
  ],
  "mentions": [],
  "tags": [],
  "card": null,
  "poll": null,
  "application": null,
  "language": null,
  "pinned": false,
  "reactions": [],
  "emoji_reactions": [],
  "bookmarked": false,
  "quote": null,
  "edited_at": null
}