Skip to content

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

```json title="activity"
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture_one_actor/actor",
  "to": [
    "http://mitra/users/admin",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/WRqRsLGXKSo",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://mitra/users/admin"
    ],
    "id": "http://pasture_one_actor/actor/vfFpjRhOurw",
    "published": "2024-02-28T16:59:17Z",
    "content": "no description",
    "attachment": {
      "type": "Document",
      "url": "http://pasture_one_actor/images/100.png"
    }
  }
}
```


```json title="mitra"
{
  "id": "018df0a8-0429-f1e4-0fb3-5902deba4139",
  "uri": "http://pasture_one_actor/actor/vfFpjRhOurw",
  "url": null,
  "created_at": "2024-02-28T16:59:17Z",
  "edited_at": null,
  "account": {
    "id": "018df09f-1a24-4e01-0141-e371bf1c13a6",
    "username": "actor",
    "acct": "actor@pasture_one_actor",
    "actor_id": "http://pasture_one_actor/actor",
    "url": "http://pasture_one_actor/actor",
    "display_name": "Test Actor",
    "created_at": "2024-02-28T16:49:35.268860Z",
    "note": "",
    "avatar": null,
    "header": null,
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 25,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "no description",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "media_attachments": [
    {
      "id": "018df0a8-0424-0938-99ef-f607566c9fcc",
      "type": "image",
      "url": "http://mitra/media/038ddc72f9a981f291b3aeda795207d6f622b8344db2b8b3ef7508407d32ba8f.png",
      "preview_url": "http://mitra/media/038ddc72f9a981f291b3aeda795207d6f622b8344db2b8b3ef7508407d32ba8f.png",
      "description": null
    }
  ],
  "mentions": [
    {
      "id": "018df09e-1831-5367-8e8c-52e388bac223",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "ipfs_cid": null,
  "token_id": null,
  "token_tx_id": null,
  "links": []
}
```

Example 2

```json title="activity"
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture_one_actor/actor",
  "to": [
    "http://mitra/users/admin",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/gz0-X0z8q2E",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://mitra/users/admin"
    ],
    "id": "http://pasture_one_actor/actor/0nb4WiJpff4",
    "published": "2024-02-28T16:59:37Z",
    "content": "text",
    "attachment": {
      "type": "Document",
      "url": "http://pasture_one_actor/images/100.png",
      "name": "name",
      "summary": "summary",
      "content": "content"
    }
  }
}
```


```json title="mitra"
{
  "id": "018df0a8-5238-faa9-34b8-612e8b2d5c34",
  "uri": "http://pasture_one_actor/actor/0nb4WiJpff4",
  "url": null,
  "created_at": "2024-02-28T16:59:37Z",
  "edited_at": null,
  "account": {
    "id": "018df09f-1a24-4e01-0141-e371bf1c13a6",
    "username": "actor",
    "acct": "actor@pasture_one_actor",
    "actor_id": "http://pasture_one_actor/actor",
    "url": "http://pasture_one_actor/actor",
    "display_name": "Test Actor",
    "created_at": "2024-02-28T16:49:35.268860Z",
    "note": "",
    "avatar": null,
    "header": null,
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 26,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "text",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "media_attachments": [
    {
      "id": "018df0a8-5234-7930-6ea8-9b61435fd314",
      "type": "image",
      "url": "http://mitra/media/2cbe4c5f5476bf97c6894481acf4f56842c0db93dc3cf42a333f1df94d5d2485.png",
      "preview_url": "http://mitra/media/2cbe4c5f5476bf97c6894481acf4f56842c0db93dc3cf42a333f1df94d5d2485.png",
      "description": "name"
    }
  ],
  "mentions": [
    {
      "id": "018df09e-1831-5367-8e8c-52e388bac223",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "ipfs_cid": null,
  "token_id": null,
  "token_tx_id": null,
  "links": []
}
```

Example 3

```json title="activity"
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture_one_actor/actor",
  "to": [
    "http://mitra/users/admin",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/0uSx2fcAJDY",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://mitra/users/admin"
    ],
    "id": "http://pasture_one_actor/actor/OQQZjaEm8R0",
    "published": "2024-02-28T16:59:57Z",
    "content": "text",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture_one_actor/assets/FediverseLogo.png",
        "name": "name",
        "imageType": "image/jpeg"
      }
    ]
  }
}
```


```json title="mitra"
{
  "id": "018df0a8-a066-e4df-45e5-b923baef6c81",
  "uri": "http://pasture_one_actor/actor/OQQZjaEm8R0",
  "url": null,
  "created_at": "2024-02-28T16:59:57Z",
  "edited_at": null,
  "account": {
    "id": "018df09f-1a24-4e01-0141-e371bf1c13a6",
    "username": "actor",
    "acct": "actor@pasture_one_actor",
    "actor_id": "http://pasture_one_actor/actor",
    "url": "http://pasture_one_actor/actor",
    "display_name": "Test Actor",
    "created_at": "2024-02-28T16:49:35.268860Z",
    "note": "",
    "avatar": null,
    "header": null,
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 27,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "text",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "media_attachments": [
    {
      "id": "018df0a8-a062-f4da-fc42-b18d5651872a",
      "type": "image",
      "url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
      "preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
      "description": "name"
    }
  ],
  "mentions": [
    {
      "id": "018df09e-1831-5367-8e8c-52e388bac223",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "ipfs_cid": null,
  "token_id": null,
  "token_tx_id": null,
  "links": []
}
```

Example 4

```json title="activity"
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture_one_actor/actor",
  "to": [
    "http://mitra/users/admin",
    "https://www.w3.org/ns/activitystreams#Public"
  ],
  "id": "http://pasture_one_actor/actor/egtJVoXFyrs",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture_one_actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://mitra/users/admin"
    ],
    "id": "http://pasture_one_actor/actor/20UUS7XSB3U",
    "published": "2024-02-28T17:00:17Z",
    "content": "no comment in attachment",
    "attachment": [
      {
        "type": "Document",
        "url": "http://pasture_one_actor/assets/FediverseLogo.png"
      }
    ]
  }
}
```


```json title="mitra"
{
  "id": "018df0a9-020b-eb3b-b6e6-43b27f8f2a58",
  "uri": "http://pasture_one_actor/actor/20UUS7XSB3U",
  "url": null,
  "created_at": "2024-02-28T17:00:17Z",
  "edited_at": null,
  "account": {
    "id": "018df09f-1a24-4e01-0141-e371bf1c13a6",
    "username": "actor",
    "acct": "actor@pasture_one_actor",
    "actor_id": "http://pasture_one_actor/actor",
    "url": "http://pasture_one_actor/actor",
    "display_name": "Test Actor",
    "created_at": "2024-02-28T16:49:35.268860Z",
    "note": "",
    "avatar": null,
    "header": null,
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 28,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "no comment in attachment",
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "media_attachments": [
    {
      "id": "018df0a9-0208-e9ed-55a9-4e7ded7acea6",
      "type": "image",
      "url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
      "preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
      "description": null
    }
  ],
  "mentions": [
    {
      "id": "018df09e-1831-5367-8e8c-52e388bac223",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "ipfs_cid": null,
  "token_id": null,
  "token_tx_id": null,
  "links": []
}
```