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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://gotosocial/users/cookie"
  ],
  "id": "http://pasture-one-actor/actor/7-Fv4lhx6KY",
  "published": "2024-10-30T16:16:36Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://gotosocial/users/cookie"
    ],
    "id": "http://pasture-one-actor/actor/rVdOhVlGcwY",
    "published": "2024-10-30T16:16:36Z",
    "content": "no description",
    "attachment": {
      "type": "Document",
      "url": "http://pasture-one-actor/images/100.png"
    },
    "tag": [
      {
        "type": "Mention",
        "href": "http://gotosocial/users/cookie"
      }
    ]
  }
}
gotosocial
{
  "id": "01JBF3DWN0WV4C753NCS407FE1",
  "created_at": "2024-10-30T16:16:36.000Z",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "language": null,
  "uri": "http://pasture-one-actor/actor/rVdOhVlGcwY",
  "url": "http://pasture-one-actor/actor/rVdOhVlGcwY",
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "favourited": false,
  "reblogged": false,
  "muted": false,
  "bookmarked": false,
  "pinned": false,
  "content": "no description",
  "reblog": null,
  "account": {
    "id": "01JBF3BAF7TWTD6EXY8466P7E3",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": true,
    "discoverable": false,
    "bot": false,
    "created_at": "2024-10-30T16:15:11.859Z",
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "avatar": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "avatar_static": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "header": "http://gotosocial/assets/default_header.png",
    "header_static": "http://gotosocial/assets/default_header.png",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 30,
    "last_status_at": "2024-10-30T16:16:36.000Z",
    "emojis": [],
    "fields": []
  },
  "media_attachments": [
    {
      "id": "01JBF3DWYJ83YVTBMWDM4V0V5Z",
      "type": "image",
      "url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DWYJ83YVTBMWDM4V0V5Z.png",
      "text_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DWYJ83YVTBMWDM4V0V5Z.png",
      "preview_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/small/01JBF3DWYJ83YVTBMWDM4V0V5Z.jpg",
      "remote_url": "http://pasture-one-actor/images/100.png",
      "preview_remote_url": null,
      "meta": {
        "original": {
          "width": 40,
          "height": 40,
          "size": "40x40",
          "aspect": 1
        },
        "small": {
          "width": 40,
          "height": 40,
          "size": "40x40",
          "aspect": 1
        },
        "focus": {
          "x": 0,
          "y": 0
        }
      },
      "description": null,
      "blurhash": "L8LM1m?1fQ?1?1j]fQj]fQfQfQfQ"
    }
  ],
  "mentions": [
    {
      "id": "01X64GSH9EB6HSAGRNPYGREMN9",
      "username": "cookie",
      "url": "http://gotosocial/@cookie",
      "acct": "cookie"
    }
  ],
  "tags": [],
  "emojis": [],
  "card": null,
  "poll": 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://gotosocial/users/cookie"
  ],
  "id": "http://pasture-one-actor/actor/iRAvcJlhI7Y",
  "published": "2024-10-30T16:16:36Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://gotosocial/users/cookie"
    ],
    "id": "http://pasture-one-actor/actor/gevLlNDODCg",
    "published": "2024-10-30T16:16:36Z",
    "content": "text",
    "attachment": {
      "type": "Document",
      "url": "http://pasture-one-actor/images/100.png",
      "name": "name",
      "summary": "summary",
      "content": "content"
    },
    "tag": [
      {
        "type": "Mention",
        "href": "http://gotosocial/users/cookie"
      }
    ]
  }
}
gotosocial
{
  "id": "01JBF3DWN0XCR43JSSXQYFRCM8",
  "created_at": "2024-10-30T16:16:36.000Z",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "language": null,
  "uri": "http://pasture-one-actor/actor/gevLlNDODCg",
  "url": "http://pasture-one-actor/actor/gevLlNDODCg",
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "favourited": false,
  "reblogged": false,
  "muted": false,
  "bookmarked": false,
  "pinned": false,
  "content": "text",
  "reblog": null,
  "account": {
    "id": "01JBF3BAF7TWTD6EXY8466P7E3",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": true,
    "discoverable": false,
    "bot": false,
    "created_at": "2024-10-30T16:15:11.859Z",
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "avatar": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "avatar_static": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "header": "http://gotosocial/assets/default_header.png",
    "header_static": "http://gotosocial/assets/default_header.png",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 31,
    "last_status_at": "2024-10-30T16:16:36.000Z",
    "emojis": [],
    "fields": []
  },
  "media_attachments": [
    {
      "id": "01JBF3DXKF2X66YPQBR1R84EB0",
      "type": "image",
      "url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DXKF2X66YPQBR1R84EB0.png",
      "text_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DXKF2X66YPQBR1R84EB0.png",
      "preview_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/small/01JBF3DXKF2X66YPQBR1R84EB0.jpg",
      "remote_url": "http://pasture-one-actor/images/100.png",
      "preview_remote_url": null,
      "meta": {
        "original": {
          "width": 40,
          "height": 40,
          "size": "40x40",
          "aspect": 1
        },
        "small": {
          "width": 40,
          "height": 40,
          "size": "40x40",
          "aspect": 1
        },
        "focus": {
          "x": 0,
          "y": 0
        }
      },
      "description": "summary",
      "blurhash": "L56ng]pffQpfpfflfQflfQfQfQfQ"
    }
  ],
  "mentions": [
    {
      "id": "01X64GSH9EB6HSAGRNPYGREMN9",
      "username": "cookie",
      "url": "http://gotosocial/@cookie",
      "acct": "cookie"
    }
  ],
  "tags": [],
  "emojis": [],
  "card": null,
  "poll": 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://gotosocial/users/cookie"
  ],
  "id": "http://pasture-one-actor/actor/WShsBCppFtM",
  "published": "2024-10-30T16:16:37Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://gotosocial/users/cookie"
    ],
    "id": "http://pasture-one-actor/actor/gSdFzCKLSYg",
    "published": "2024-10-30T16:16:37Z",
    "content": "text",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture-one-actor/assets/FediverseLogo.png",
        "name": "name",
        "imageType": "image/jpeg"
      }
    ],
    "tag": [
      {
        "type": "Mention",
        "href": "http://gotosocial/users/cookie"
      }
    ]
  }
}
gotosocial
{
  "id": "01JBF3DXM8G40HBXFA8AT50QKQ",
  "created_at": "2024-10-30T16:16:37.000Z",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "language": null,
  "uri": "http://pasture-one-actor/actor/gSdFzCKLSYg",
  "url": "http://pasture-one-actor/actor/gSdFzCKLSYg",
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "favourited": false,
  "reblogged": false,
  "muted": false,
  "bookmarked": false,
  "pinned": false,
  "content": "text",
  "reblog": null,
  "account": {
    "id": "01JBF3BAF7TWTD6EXY8466P7E3",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": true,
    "discoverable": false,
    "bot": false,
    "created_at": "2024-10-30T16:15:11.859Z",
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "avatar": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "avatar_static": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "header": "http://gotosocial/assets/default_header.png",
    "header_static": "http://gotosocial/assets/default_header.png",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 32,
    "last_status_at": "2024-10-30T16:16:37.000Z",
    "emojis": [],
    "fields": []
  },
  "media_attachments": [
    {
      "id": "01JBF3DY95FW913RX7220K0AYY",
      "type": "image",
      "url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DY95FW913RX7220K0AYY.png",
      "text_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DY95FW913RX7220K0AYY.png",
      "preview_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/small/01JBF3DY95FW913RX7220K0AYY.jpg",
      "remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "preview_remote_url": null,
      "meta": {
        "original": {
          "width": 1548,
          "height": 1548,
          "size": "1548x1548",
          "aspect": 1
        },
        "small": {
          "width": 512,
          "height": 512,
          "size": "512x512",
          "aspect": 1
        },
        "focus": {
          "x": 0,
          "y": 0
        }
      },
      "description": "name",
      "blurhash": "LIB{x~.}9Fcn}gnOEUxBDlK[N1wi"
    }
  ],
  "mentions": [
    {
      "id": "01X64GSH9EB6HSAGRNPYGREMN9",
      "username": "cookie",
      "url": "http://gotosocial/@cookie",
      "acct": "cookie"
    }
  ],
  "tags": [],
  "emojis": [],
  "card": null,
  "poll": 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://gotosocial/users/cookie"
  ],
  "id": "http://pasture-one-actor/actor/6QaDX8M8GYg",
  "published": "2024-10-30T16:16:38Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://gotosocial/users/cookie"
    ],
    "id": "http://pasture-one-actor/actor/KTqA5PQLmUI",
    "published": "2024-10-30T16:16:38Z",
    "content": "no comment in attachment",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture-one-actor/assets/FediverseLogo.png"
      }
    ],
    "tag": [
      {
        "type": "Mention",
        "href": "http://gotosocial/users/cookie"
      }
    ]
  }
}
gotosocial
{
  "id": "01JBF3DYKGW6MTYJZXE48X0RBC",
  "created_at": "2024-10-30T16:16:38.000Z",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "sensitive": false,
  "spoiler_text": "",
  "visibility": "public",
  "language": null,
  "uri": "http://pasture-one-actor/actor/KTqA5PQLmUI",
  "url": "http://pasture-one-actor/actor/KTqA5PQLmUI",
  "replies_count": 0,
  "reblogs_count": 0,
  "favourites_count": 0,
  "favourited": false,
  "reblogged": false,
  "muted": false,
  "bookmarked": false,
  "pinned": false,
  "content": "no comment in attachment",
  "reblog": null,
  "account": {
    "id": "01JBF3BAF7TWTD6EXY8466P7E3",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "display_name": "Test Actor",
    "locked": true,
    "discoverable": false,
    "bot": false,
    "created_at": "2024-10-30T16:15:11.859Z",
    "note": "",
    "url": "http://pasture-one-actor/actor",
    "avatar": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "avatar_static": "http://gotosocial/assets/default_avatars/GoToSocial_icon6.png",
    "header": "http://gotosocial/assets/default_header.png",
    "header_static": "http://gotosocial/assets/default_header.png",
    "followers_count": 0,
    "following_count": 0,
    "statuses_count": 33,
    "last_status_at": "2024-10-30T16:16:38.000Z",
    "emojis": [],
    "fields": []
  },
  "media_attachments": [
    {
      "id": "01JBF3DYYYCDPWFTBG8NNVEWW5",
      "type": "image",
      "url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DYYYCDPWFTBG8NNVEWW5.png",
      "text_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/original/01JBF3DYYYCDPWFTBG8NNVEWW5.png",
      "preview_url": "http://gotosocial/fileserver/01JBF3BAF7TWTD6EXY8466P7E3/attachment/small/01JBF3DYYYCDPWFTBG8NNVEWW5.jpg",
      "remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
      "preview_remote_url": null,
      "meta": {
        "original": {
          "width": 1548,
          "height": 1548,
          "size": "1548x1548",
          "aspect": 1
        },
        "small": {
          "width": 512,
          "height": 512,
          "size": "512x512",
          "aspect": 1
        },
        "focus": {
          "x": 0,
          "y": 0
        }
      },
      "description": null,
      "blurhash": "LIB{x~.}9Fcn}gnOEUxBDlK[N1wi"
    }
  ],
  "mentions": [
    {
      "id": "01X64GSH9EB6HSAGRNPYGREMN9",
      "username": "cookie",
      "url": "http://gotosocial/@cookie",
      "acct": "cookie"
    }
  ],
  "tags": [],
  "emojis": [],
  "card": null,
  "poll": null
}