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://mitra/users/admin"
],
"id": "http://pasture-one-actor/activity/nIfzFVH3NcY",
"published": "2025-08-19T08:25:49Z",
"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/object/WwCd71Hfm8g",
"published": "2025-08-19T08:25:49Z",
"content": "no description",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png"
}
}
}
mitra
{
"id": "0198c16f-4362-eb8f-8c34-097ec5d415ae",
"uri": "http://pasture-one-actor/object/WwCd71Hfm8g",
"url": "http://pasture-one-actor/object/WwCd71Hfm8g",
"created_at": "2025-08-19T08:25:49.000Z",
"edited_at": null,
"account": {
"id": "0198c16d-6ca2-119d-3bb9-715ace3fa0ab",
"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": "2025-08-19T08:23:50.689Z",
"note": "",
"avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
"header": "http://mitra/api/v1/accounts/identicon",
"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 description",
"language": null,
"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,
"poll": null,
"media_attachments": [
{
"id": "0198c16f-435f-c1d7-bc4d-f3674ccc958b",
"type": "image",
"url": "http://mitra/media/f37f4b26b1bfe2912c8064161f6bb165231cffe748020945d6198fcfe1a2dce9.png",
"preview_url": "http://mitra/media/f37f4b26b1bfe2912c8064161f6bb165231cffe748020945d6198fcfe1a2dce9.png",
"description": null
}
],
"quote": null,
"mentions": [
{
"id": "0198c16c-2814-7f6f-b417-cc3fd1baebc3",
"username": "admin",
"acct": "admin",
"url": "http://mitra/users/admin"
}
],
"tags": [],
"emojis": [],
"favourited": false,
"reblogged": false,
"bookmarked": false,
"pleroma": {
"emoji_reactions": [],
"in_reply_to_account_acct": null,
"parent_visible": true,
"quote": null,
"quote_visible": true
},
"hidden": false,
"ipfs_cid": null,
"links": []
}
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://mitra/users/admin"
],
"id": "http://pasture-one-actor/activity/HIonhvBElmY",
"published": "2025-08-19T08:25:51Z",
"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/object/RqxnQhEd6tg",
"published": "2025-08-19T08:25:51Z",
"content": "text",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
mitra
{
"id": "0198c16f-4963-84ac-6c45-b0507e504d06",
"uri": "http://pasture-one-actor/object/RqxnQhEd6tg",
"url": "http://pasture-one-actor/object/RqxnQhEd6tg",
"created_at": "2025-08-19T08:25:51.000Z",
"edited_at": null,
"account": {
"id": "0198c16d-6ca2-119d-3bb9-715ace3fa0ab",
"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": "2025-08-19T08:23:50.689Z",
"note": "",
"avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
"header": "http://mitra/api/v1/accounts/identicon",
"locked": false,
"mention_policy": "none",
"bot": false,
"identity_proofs": [],
"payment_options": [],
"fields": [],
"emojis": [],
"followers_count": 0,
"following_count": 0,
"subscribers_count": 0,
"statuses_count": 29,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "text",
"language": null,
"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,
"poll": null,
"media_attachments": [
{
"id": "0198c16f-495d-7ead-2628-ada56f004738",
"type": "image",
"url": "http://mitra/media/8e6557e52c2dec49bd94ec31589c54d3aebb6a3d91c7d218ff2eac07d63fe0e4.png",
"preview_url": "http://mitra/media/8e6557e52c2dec49bd94ec31589c54d3aebb6a3d91c7d218ff2eac07d63fe0e4.png",
"description": "name"
}
],
"quote": null,
"mentions": [
{
"id": "0198c16c-2814-7f6f-b417-cc3fd1baebc3",
"username": "admin",
"acct": "admin",
"url": "http://mitra/users/admin"
}
],
"tags": [],
"emojis": [],
"favourited": false,
"reblogged": false,
"bookmarked": false,
"pleroma": {
"emoji_reactions": [],
"in_reply_to_account_acct": null,
"parent_visible": true,
"quote": null,
"quote_visible": true
},
"hidden": false,
"ipfs_cid": null,
"links": []
}
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://mitra/users/admin"
],
"id": "http://pasture-one-actor/activity/f-RO8UH2fgM",
"published": "2025-08-19T08:25:53Z",
"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/object/APh5bJfB9PM",
"published": "2025-08-19T08:25:53Z",
"content": "text",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
mitra
{
"id": "0198c16f-4f3d-a2f6-2651-aed51f37c627",
"uri": "http://pasture-one-actor/object/APh5bJfB9PM",
"url": "http://pasture-one-actor/object/APh5bJfB9PM",
"created_at": "2025-08-19T08:25:53.000Z",
"edited_at": null,
"account": {
"id": "0198c16d-6ca2-119d-3bb9-715ace3fa0ab",
"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": "2025-08-19T08:23:50.689Z",
"note": "",
"avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
"header": "http://mitra/api/v1/accounts/identicon",
"locked": false,
"mention_policy": "none",
"bot": false,
"identity_proofs": [],
"payment_options": [],
"fields": [],
"emojis": [],
"followers_count": 0,
"following_count": 0,
"subscribers_count": 0,
"statuses_count": 30,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "text<p><a href=\"http://pasture-one-actor/assets/FediverseLogo.png\" rel=\"noopener\">http://pasture-one-actor/assets/FediverseLogo.png</a></p>",
"language": null,
"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,
"poll": null,
"media_attachments": [],
"quote": null,
"mentions": [
{
"id": "0198c16c-2814-7f6f-b417-cc3fd1baebc3",
"username": "admin",
"acct": "admin",
"url": "http://mitra/users/admin"
}
],
"tags": [],
"emojis": [],
"favourited": false,
"reblogged": false,
"bookmarked": false,
"pleroma": {
"emoji_reactions": [],
"in_reply_to_account_acct": null,
"parent_visible": true,
"quote": null,
"quote_visible": true
},
"hidden": false,
"ipfs_cid": null,
"links": []
}
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://mitra/users/admin"
],
"id": "http://pasture-one-actor/activity/qv0ZFLJo8DI",
"published": "2025-08-19T08:25:54Z",
"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/object/wqcNoSIvEUM",
"published": "2025-08-19T08:25:54Z",
"content": "no comment in attachment",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
mitra
{
"id": "0198c16f-5501-1861-650a-91b53cc894fa",
"uri": "http://pasture-one-actor/object/wqcNoSIvEUM",
"url": "http://pasture-one-actor/object/wqcNoSIvEUM",
"created_at": "2025-08-19T08:25:54.000Z",
"edited_at": null,
"account": {
"id": "0198c16d-6ca2-119d-3bb9-715ace3fa0ab",
"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": "2025-08-19T08:23:50.689Z",
"note": "",
"avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
"header": "http://mitra/api/v1/accounts/identicon",
"locked": false,
"mention_policy": "none",
"bot": false,
"identity_proofs": [],
"payment_options": [],
"fields": [],
"emojis": [],
"followers_count": 0,
"following_count": 0,
"subscribers_count": 0,
"statuses_count": 31,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "no comment in attachment<p><a href=\"http://pasture-one-actor/assets/FediverseLogo.png\" rel=\"noopener\">http://pasture-one-actor/assets/FediverseLogo.png</a></p>",
"language": null,
"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,
"poll": null,
"media_attachments": [],
"quote": null,
"mentions": [
{
"id": "0198c16c-2814-7f6f-b417-cc3fd1baebc3",
"username": "admin",
"acct": "admin",
"url": "http://mitra/users/admin"
}
],
"tags": [],
"emojis": [],
"favourited": false,
"reblogged": false,
"bookmarked": false,
"pleroma": {
"emoji_reactions": [],
"in_reply_to_account_acct": null,
"parent_visible": true,
"quote": null,
"quote_visible": true
},
"hidden": false,
"ipfs_cid": null,
"links": []
}