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": [
"https://www.w3.org/ns/activitystreams#Public",
"http://mitra/users/admin"
],
"id": "http://pasture-one-actor/activity/gdRKGFV_Zi8",
"published": "2025-09-06T14:02:22Z",
"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/V4ignUYIctk",
"published": "2025-09-06T14:02:22Z",
"content": "no description",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png"
}
}
}
mitra
{
"id": "01991f55-d9c7-4704-7492-3b28f20d2211",
"uri": "http://pasture-one-actor/object/V4ignUYIctk",
"url": "http://pasture-one-actor/object/V4ignUYIctk",
"created_at": "2025-09-06T14:02:22.000Z",
"edited_at": null,
"account": {
"id": "01991f53-7154-4db7-39b7-32994d52b299",
"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": "2025-09-06T13:59:46.260Z",
"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": 69,
"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": "01991f55-d9c3-4073-dfea-164d888ba8b1",
"type": "image",
"url": "http://mitra/media/006366dc79d7b9787a35faf2dd6d172e049d79a7ccc9e34b82fb449854a7dc89.png",
"preview_url": "http://mitra/media/006366dc79d7b9787a35faf2dd6d172e049d79a7ccc9e34b82fb449854a7dc89.png",
"description": null
}
],
"quote": null,
"mentions": [
{
"id": "01991f52-35d7-ec78-01e6-d1713631a2d7",
"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/fP6jjSXOAXQ",
"published": "2025-09-06T14:02:24Z",
"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/jHb5DuxSJYA",
"published": "2025-09-06T14:02:24Z",
"content": "text",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
mitra
{
"id": "01991f55-dfa4-2175-bfec-a925bd3f5fb7",
"uri": "http://pasture-one-actor/object/jHb5DuxSJYA",
"url": "http://pasture-one-actor/object/jHb5DuxSJYA",
"created_at": "2025-09-06T14:02:24.000Z",
"edited_at": null,
"account": {
"id": "01991f53-7154-4db7-39b7-32994d52b299",
"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": "2025-09-06T13:59:46.260Z",
"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": 70,
"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": "01991f55-dfa0-fc39-1269-8e989ec51c3c",
"type": "image",
"url": "http://mitra/media/480797663182b662d6916f67beff90154962f3f35f8712ae01f52229c1398114.png",
"preview_url": "http://mitra/media/480797663182b662d6916f67beff90154962f3f35f8712ae01f52229c1398114.png",
"description": "name"
}
],
"quote": null,
"mentions": [
{
"id": "01991f52-35d7-ec78-01e6-d1713631a2d7",
"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/zY_Wte6FBzo",
"published": "2025-09-06T14:02:25Z",
"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/03u8HM6RJs8",
"published": "2025-09-06T14:02:25Z",
"content": "text",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
mitra
{
"id": "01991f55-e598-2a2e-ae76-789d959c4284",
"uri": "http://pasture-one-actor/object/03u8HM6RJs8",
"url": "http://pasture-one-actor/object/03u8HM6RJs8",
"created_at": "2025-09-06T14:02:25.000Z",
"edited_at": null,
"account": {
"id": "01991f53-7154-4db7-39b7-32994d52b299",
"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": "2025-09-06T13:59:46.260Z",
"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": "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": "01991f55-e594-d02c-de8c-120a69bb1782",
"type": "image",
"url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"description": "name"
}
],
"quote": null,
"mentions": [
{
"id": "01991f52-35d7-ec78-01e6-d1713631a2d7",
"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/GPacbdGjouM",
"published": "2025-09-06T14:02:27Z",
"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/_6FI_Qm-BwQ",
"published": "2025-09-06T14:02:27Z",
"content": "no comment in attachment",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
mitra
{
"id": "01991f55-eb6a-703e-1b02-66a82eac39ac",
"uri": "http://pasture-one-actor/object/_6FI_Qm-BwQ",
"url": "http://pasture-one-actor/object/_6FI_Qm-BwQ",
"created_at": "2025-09-06T14:02:27.000Z",
"edited_at": null,
"account": {
"id": "01991f53-7154-4db7-39b7-32994d52b299",
"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": "2025-09-06T13:59:46.260Z",
"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": "no comment in attachment",
"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": "01991f55-eb65-d902-c5e5-2bc995234527",
"type": "image",
"url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"description": null
}
],
"quote": null,
"mentions": [
{
"id": "01991f52-35d7-ec78-01e6-d1713631a2d7",
"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": []
}