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/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/activity/hC_J-9zzG1c",
"published": "2025-08-15T11:13:09Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://sharkey/users/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/object/QyT_mpTr67I",
"published": "2025-08-15T11:13:09Z",
"content": "no description",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png"
}
}
}
sharkey
{
"id": "abganb0o0e9f0014",
"uri": "http://pasture-one-actor/object/QyT_mpTr67I",
"url": "http://pasture-one-actor/object/QyT_mpTr67I",
"account": {
"id": "abgal1vf0e9f0004",
"username": "actor",
"acct": "actor@pasture-one-actor",
"fqn": "actor@pasture-one-actor",
"display_name": "Test Actor",
"locked": false,
"created_at": "2025-08-15T11:11:23.835Z",
"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,
"noindex": false,
"group": null,
"suspended": false,
"limited": false
},
"in_reply_to_id": null,
"in_reply_to_account_id": null,
"reblog": null,
"content": "<p>no description</p>",
"content_type": "text/x.misskeymarkdown",
"text": "no description",
"created_at": "2025-08-15T11:13:09.000Z",
"edited_at": null,
"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": "abganb6p0e9f0013",
"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,
"original": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1,
"frame_rate": "undefined"
},
"size": "40x40",
"aspect": 1
},
"description": null,
"blurhash": "e1H,K5^UfQ^UfQ^Uj[fQj[fQfQfQfQfQfQ^Uj[fQj[fQfQfQfQfQfQ"
}
],
"mentions": [],
"tags": [],
"card": null,
"poll": null,
"application": null,
"language": null,
"pinned": false,
"bookmarked": false,
"quote": null,
"reactions": []
}
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/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/activity/6e3NGQZHdWw",
"published": "2025-08-15T11:13:09Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://sharkey/users/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/object/0BeZme9lEL8",
"published": "2025-08-15T11:13:09Z",
"content": "text",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
sharkey
{
"id": "abganb0o0e9f0016",
"uri": "http://pasture-one-actor/object/0BeZme9lEL8",
"url": "http://pasture-one-actor/object/0BeZme9lEL8",
"account": {
"id": "abgal1vf0e9f0004",
"username": "actor",
"acct": "actor@pasture-one-actor",
"fqn": "actor@pasture-one-actor",
"display_name": "Test Actor",
"locked": false,
"created_at": "2025-08-15T11:11:23.835Z",
"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,
"noindex": false,
"group": null,
"suspended": false,
"limited": false
},
"in_reply_to_id": null,
"in_reply_to_account_id": null,
"reblog": null,
"content": "<p>text</p>",
"content_type": "text/x.misskeymarkdown",
"text": "text",
"created_at": "2025-08-15T11:13:09.000Z",
"edited_at": null,
"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": "abganbpx0e9f0015",
"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,
"original": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1,
"frame_rate": "undefined"
},
"size": "40x40",
"aspect": 1
},
"description": "name",
"blurhash": "e4J-VN.gfQ.gfQ.gj@fQj@fQfQfQfQfQfQ.gj@fQj@fQfQfQfQfQfQ"
}
],
"mentions": [],
"tags": [],
"card": null,
"poll": null,
"application": null,
"language": null,
"pinned": false,
"bookmarked": false,
"quote": null,
"reactions": []
}
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/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/activity/T07Qx0L16vU",
"published": "2025-08-15T11:13:10Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://sharkey/users/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/object/tVB3kOB2rSM",
"published": "2025-08-15T11:13:10Z",
"content": "text",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
no result
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/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/activity/LiAB0PIgUOg",
"published": "2025-08-15T11:13:22Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://sharkey/users/abgajfhntvnz0003"
],
"id": "http://pasture-one-actor/object/Bi4UjlbMl24",
"published": "2025-08-15T11:13:22Z",
"content": "no comment in attachment",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
no result