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": [
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/GNE0EbATY-4",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
    ],
    "id": "http://pasture_one_actor/actor/b1L1VjpKF3g",
    "published": "2024-03-01T16:23:27Z",
    "content": "no description",
    "attachment": {
      "type": "Document",
      "url": "http://pasture_one_actor/images/100.png"
    }
  }
}

bovine

{
  "attachment": [
    {
      "type": "Document",
      "url": "http://pasture_one_actor/images/100.png"
    }
  ],
  "attributedTo": "http://pasture_one_actor/actor",
  "content": "no description",
  "id": "http://pasture_one_actor/actor/b1L1VjpKF3g",
  "published": "2024-03-01T16:23:27Z",
  "to": [
    "as:Public",
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
  ],
  "type": "Note"
}

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": [
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/9QpJfdnG31U",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
    ],
    "id": "http://pasture_one_actor/actor/sTlpNyBA_W4",
    "published": "2024-03-01T16:23:30Z",
    "content": "text",
    "attachment": {
      "type": "Document",
      "url": "http://pasture_one_actor/images/100.png",
      "name": "name",
      "summary": "summary",
      "content": "content"
    }
  }
}

bovine

{
  "attachment": [
    {
      "content": "content",
      "name": "name",
      "summary": "summary",
      "type": "Document",
      "url": "http://pasture_one_actor/images/100.png"
    }
  ],
  "attributedTo": "http://pasture_one_actor/actor",
  "content": "text",
  "id": "http://pasture_one_actor/actor/sTlpNyBA_W4",
  "published": "2024-03-01T16:23:30Z",
  "to": [
    "as:Public",
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
  ],
  "type": "Note"
}

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": [
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/4U-xSMQJqnQ",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
    ],
    "id": "http://pasture_one_actor/actor/m5RgewYGLkU",
    "published": "2024-03-01T16:23:32Z",
    "content": "text",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture_one_actor/assets/FediverseLogo.png",
        "name": "name",
        "imageType": "image/jpeg"
      }
    ]
  }
}

bovine

{
  "attachment": [
    {
      "b1": "image/jpeg",
      "name": "name",
      "type": "Document",
      "url": "http://pasture_one_actor/assets/FediverseLogo.png"
    }
  ],
  "attributedTo": "http://pasture_one_actor/actor",
  "content": "text",
  "id": "http://pasture_one_actor/actor/m5RgewYGLkU",
  "published": "2024-03-01T16:23:32Z",
  "to": [
    "as:Public",
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
  ],
  "type": "Note"
}

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": [
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/7D7aV6P14sE",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
    ],
    "id": "http://pasture_one_actor/actor/GJlmSq82c_o",
    "published": "2024-03-01T16:23:34Z",
    "content": "no comment in attachment",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture_one_actor/assets/FediverseLogo.png"
      }
    ]
  }
}

bovine

{
  "attachment": [
    {
      "type": "Document",
      "url": "http://pasture_one_actor/assets/FediverseLogo.png"
    }
  ],
  "attributedTo": "http://pasture_one_actor/actor",
  "content": "no comment in attachment",
  "id": "http://pasture_one_actor/actor/GJlmSq82c_o",
  "published": "2024-03-01T16:23:34Z",
  "to": [
    "as:Public",
    "http://bovine/endpoints/cCymvw_8wcviEwAgrvkkb23N6OGZlQ6wMW9bWKqWBYM"
  ],
  "type": "Note"
}