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. misskey, 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://mitra/users/admin",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/5hJiZTP3Frs",
"published": "2025-10-04T15:16:52Z",
"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/Fq_OacAaXTM",
"published": "2025-10-04T15:16:52Z",
"content": "no description",
"attachment": {
"type": "Image",
"url": "http://pasture-one-actor/images/bab0c3cd-c97a-4569-a6e0-6de41e29b98d.png"
}
}
}
mitra
{
"id": "0199afcc-1bfe-47aa-f2b5-85e58c9c8f31",
"uri": "http://pasture-one-actor/object/Fq_OacAaXTM",
"url": "http://pasture-one-actor/object/Fq_OacAaXTM",
"created_at": "2025-10-04T15:16:52.000Z",
"edited_at": null,
"account": {
"id": "0199afc9-ae4e-04cd-2b42-9cd0d025cd92",
"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": "2025-10-04T15:14:14.222Z",
"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": 71,
"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": "0199afcc-1bfb-41e2-8b2b-7411715d7cd0",
"type": "image",
"url": "http://mitra/media/97d6192f545d418a4eb71872b1a00fe090c397122c7698b0b449449db6391735.png",
"preview_url": "http://mitra/media/97d6192f545d418a4eb71872b1a00fe090c397122c7698b0b449449db6391735.png",
"description": null
}
],
"quote": null,
"mentions": [
{
"id": "0199afc8-6e49-a175-e817-c99beef88df8",
"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": [
"http://mitra/users/admin",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/sUaPFhNuG_c",
"published": "2025-10-04T15:16:53Z",
"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/jhNFLXco-us",
"published": "2025-10-04T15:16:53Z",
"content": "name, summary and content",
"attachment": {
"type": "Image",
"url": "http://pasture-one-actor/images/1d04aff4-47ed-4415-8bee-659a6468e5e4.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
mitra
{
"id": "0199afcc-21f8-5882-5fa1-78d73b9c3341",
"uri": "http://pasture-one-actor/object/jhNFLXco-us",
"url": "http://pasture-one-actor/object/jhNFLXco-us",
"created_at": "2025-10-04T15:16:53.000Z",
"edited_at": null,
"account": {
"id": "0199afc9-ae4e-04cd-2b42-9cd0d025cd92",
"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": "2025-10-04T15:14:14.222Z",
"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": 72,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "name, summary and content",
"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": "0199afcc-21f2-16e3-ef1b-945e44898fe2",
"type": "image",
"url": "http://mitra/media/c56193eb43f0fe8c2224914f3557be82e3b23aa39bddef91b9a0e869ac7e66d6.png",
"preview_url": "http://mitra/media/c56193eb43f0fe8c2224914f3557be82e3b23aa39bddef91b9a0e869ac7e66d6.png",
"description": "name"
}
],
"quote": null,
"mentions": [
{
"id": "0199afc8-6e49-a175-e817-c99beef88df8",
"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": [
"http://mitra/users/admin",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/2MU6__uCbjE",
"published": "2025-10-04T15:16:55Z",
"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/eRZycFliD5Q",
"published": "2025-10-04T15:16:55Z",
"content": "only name",
"attachment": [
{
"type": "Image",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
mitra
{
"id": "0199afcc-27f0-e62d-4bec-1911e6081f3b",
"uri": "http://pasture-one-actor/object/eRZycFliD5Q",
"url": "http://pasture-one-actor/object/eRZycFliD5Q",
"created_at": "2025-10-04T15:16:55.000Z",
"edited_at": null,
"account": {
"id": "0199afc9-ae4e-04cd-2b42-9cd0d025cd92",
"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": "2025-10-04T15:14:14.222Z",
"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": 73,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "only name",
"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": "0199afcc-27ea-7f4f-307c-9fa72287c2cd",
"type": "image",
"url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"description": "name"
}
],
"quote": null,
"mentions": [
{
"id": "0199afc8-6e49-a175-e817-c99beef88df8",
"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": [
"http://mitra/users/admin",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/Z3h6bjVh98E",
"published": "2025-10-04T15:16:56Z",
"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/vktZZbuqxLY",
"published": "2025-10-04T15:16:56Z",
"content": "only summary",
"attachment": {
"type": "Image",
"url": "http://pasture-one-actor/images/9a07a7e9-1708-4f66-b66c-baaf1140dd13.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
mitra
{
"id": "0199afcc-2d92-af94-72c3-fedfbcb3d305",
"uri": "http://pasture-one-actor/object/vktZZbuqxLY",
"url": "http://pasture-one-actor/object/vktZZbuqxLY",
"created_at": "2025-10-04T15:16:56.000Z",
"edited_at": null,
"account": {
"id": "0199afc9-ae4e-04cd-2b42-9cd0d025cd92",
"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": "2025-10-04T15:14:14.222Z",
"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": 74,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "only summary",
"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": "0199afcc-2d8e-2d62-f640-594ade3c3acd",
"type": "image",
"url": "http://mitra/media/d7acf567fa338656d2e1c46f415a3e2786210627960ed31f847162f3b5ee9225.png",
"preview_url": "http://mitra/media/d7acf567fa338656d2e1c46f415a3e2786210627960ed31f847162f3b5ee9225.png",
"description": "name"
}
],
"quote": null,
"mentions": [
{
"id": "0199afc8-6e49-a175-e817-c99beef88df8",
"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 5¶
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/activity/8_0MWF1QjpE",
"published": "2025-10-04T15:16:58Z",
"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/0JPc7DNQLcc",
"published": "2025-10-04T15:16:58Z",
"content": "only content",
"attachment": {
"type": "Image",
"url": "http://pasture-one-actor/images/0821d9ea-4926-4019-8225-b97ce420ac2d.png",
"content": "content"
}
}
}
mitra
{
"id": "0199afcc-337a-0ae4-8932-8dfab10f949e",
"uri": "http://pasture-one-actor/object/0JPc7DNQLcc",
"url": "http://pasture-one-actor/object/0JPc7DNQLcc",
"created_at": "2025-10-04T15:16:58.000Z",
"edited_at": null,
"account": {
"id": "0199afc9-ae4e-04cd-2b42-9cd0d025cd92",
"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": "2025-10-04T15:14:14.222Z",
"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": 75,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "only content",
"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": "0199afcc-3375-ec74-acda-ff3f21d80c64",
"type": "image",
"url": "http://mitra/media/6b4be36cde0aa59834cfaee64f6cdd0ce21727fdbca5a9b316f52f4acd1224da.png",
"preview_url": "http://mitra/media/6b4be36cde0aa59834cfaee64f6cdd0ce21727fdbca5a9b316f52f4acd1224da.png",
"description": null
}
],
"quote": null,
"mentions": [
{
"id": "0199afc8-6e49-a175-e817-c99beef88df8",
"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 6¶
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/activity/X_ik-YPpVVE",
"published": "2025-10-04T15:16:59Z",
"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/ghpVLSuLRAE",
"published": "2025-10-04T15:16:59Z",
"content": "no comment in attachment; reused image",
"attachment": [
{
"type": "Image",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
mitra
{
"id": "0199afcc-3957-7173-2045-4d5304dabe6b",
"uri": "http://pasture-one-actor/object/ghpVLSuLRAE",
"url": "http://pasture-one-actor/object/ghpVLSuLRAE",
"created_at": "2025-10-04T15:16:59.000Z",
"edited_at": null,
"account": {
"id": "0199afc9-ae4e-04cd-2b42-9cd0d025cd92",
"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": "2025-10-04T15:14:14.222Z",
"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": 76,
"source": null,
"role": null,
"authentication_methods": null,
"client_config": null
},
"content": "no comment in attachment; reused image",
"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": "0199afcc-3953-4cda-9d81-3fff3b340f9d",
"type": "image",
"url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"description": null
}
],
"quote": null,
"mentions": [
{
"id": "0199afc8-6e49-a175-e817-c99beef88df8",
"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": []
}