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/actor/QOrtZr1MthU",
"published": "2025-02-07T20:57:38Z",
"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/K_HFjVh5Kw4",
"published": "2025-02-07T20:57:38Z",
"content": "no description",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png"
}
}
}
misskey
{
"id": "a3yt0ou0pl2g0015",
"createdAt": "2025-02-07T20:49:39.000Z",
"userId": "a3ysz1b3pl2g0002",
"user": {
"id": "a3ysz1b3pl2g0002",
"name": "Test Actor",
"username": "actor",
"host": "pasture-one-actor",
"avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
"avatarBlurhash": null,
"avatarDecorations": [],
"isBot": false,
"isCat": false,
"instance": {
"name": null,
"softwareName": null,
"softwareVersion": null,
"iconUrl": null,
"faviconUrl": null,
"themeColor": null
},
"emojis": {},
"onlineStatus": "unknown"
},
"text": "no description",
"cw": null,
"visibility": "public",
"localOnly": false,
"reactionAcceptance": null,
"renoteCount": 0,
"repliesCount": 0,
"reactionCount": 0,
"reactions": {},
"reactionEmojis": {},
"emojis": {},
"fileIds": [
"a3yt0p1mpl2g0014"
],
"files": [
{
"id": "a3yt0p1mpl2g0014",
"createdAt": "2025-02-07T20:49:39.274Z",
"name": "100.png",
"type": "image/png",
"md5": "1e5918785f3011d3a0bb98d94232796d",
"size": 0,
"isSensitive": false,
"blurhash": "e1K=Bb|wfQ|wfQ|wjtfQjtfQfQfQfQfQfQ|wjtfQjtfQfQfQfQfQfQ",
"properties": {
"width": 40,
"height": 40
},
"url": "http://pasture-one-actor/images/100.png",
"thumbnailUrl": "http://pasture-one-actor/images/100.png",
"comment": null,
"folderId": null,
"folder": null,
"userId": "a3ysz1b3pl2g0002",
"user": null
}
],
"replyId": null,
"renoteId": null,
"uri": "http://pasture-one-actor/actor/dT3_2uGOD4o",
"clippedCount": 0
}
mitra
{
"id": "0194e234-369c-ff27-a6f4-758c96c6f29c",
"uri": "http://pasture-one-actor/actor/K_HFjVh5Kw4",
"url": "http://pasture-one-actor/actor/K_HFjVh5Kw4",
"created_at": "2025-02-07T20:57:38Z",
"edited_at": null,
"account": {
"id": "0194e232-b067-124b-0799-4ade30ddd9a9",
"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": "2025-02-07T20:56:00.359685Z",
"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": "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,
"poll": null,
"media_attachments": [
{
"id": "0194e234-3698-ba56-b873-c6c755842aeb",
"type": "image",
"url": "http://mitra/media/d82b31e4f291070d39b8bcc089a2e08118b9ebbc143aafc6b26cb84299a6bb62.png",
"preview_url": "http://mitra/media/d82b31e4f291070d39b8bcc089a2e08118b9ebbc143aafc6b26cb84299a6bb62.png",
"description": null
}
],
"mentions": [
{
"id": "0194e231-607b-c1e5-c5c3-2ce84c557b8b",
"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": 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/actor/mxQIdj6Eeak",
"published": "2025-02-07T20:57:40Z",
"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/let60KibFhE",
"published": "2025-02-07T20:57:40Z",
"content": "text",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
misskey
{
"id": "a3yt0ou0pl2g0017",
"createdAt": "2025-02-07T20:49:39.000Z",
"userId": "a3ysz1b3pl2g0002",
"user": {
"id": "a3ysz1b3pl2g0002",
"name": "Test Actor",
"username": "actor",
"host": "pasture-one-actor",
"avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
"avatarBlurhash": null,
"avatarDecorations": [],
"isBot": false,
"isCat": false,
"instance": {
"name": null,
"softwareName": null,
"softwareVersion": null,
"iconUrl": null,
"faviconUrl": null,
"themeColor": null
},
"emojis": {},
"onlineStatus": "unknown"
},
"text": "text",
"cw": null,
"visibility": "public",
"localOnly": false,
"reactionAcceptance": null,
"renoteCount": 0,
"repliesCount": 0,
"reactionCount": 0,
"reactions": {},
"reactionEmojis": {},
"emojis": {},
"fileIds": [
"a3yt0plhpl2g0016"
],
"files": [
{
"id": "a3yt0plhpl2g0016",
"createdAt": "2025-02-07T20:49:39.989Z",
"name": "100.png",
"type": "image/png",
"md5": "6d2f26215c82116b158ac0c1819f536b",
"size": 0,
"isSensitive": false,
"blurhash": "e0GW}z|$fQ|$fQ|$jufQjufQfQfQfQfQfQ|$jufQjufQfQfQfQfQfQ",
"properties": {
"width": 40,
"height": 40
},
"url": "http://pasture-one-actor/images/100.png",
"thumbnailUrl": "http://pasture-one-actor/images/100.png",
"comment": "name",
"folderId": null,
"folder": null,
"userId": "a3ysz1b3pl2g0002",
"user": null
}
],
"replyId": null,
"renoteId": null,
"uri": "http://pasture-one-actor/actor/Xm9U3yt8k5g",
"clippedCount": 0
}
mitra
{
"id": "0194e234-3c91-d3e5-a151-219bdd816fdd",
"uri": "http://pasture-one-actor/actor/let60KibFhE",
"url": "http://pasture-one-actor/actor/let60KibFhE",
"created_at": "2025-02-07T20:57:40Z",
"edited_at": null,
"account": {
"id": "0194e232-b067-124b-0799-4ade30ddd9a9",
"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": "2025-02-07T20:56:00.359685Z",
"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": "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,
"poll": null,
"media_attachments": [
{
"id": "0194e234-3c89-4df8-8705-07eb2af58b2a",
"type": "image",
"url": "http://mitra/media/e5aa4cd95e47f0bb320ab0c44d927ef293a104d85d4b801ab39d4760d38385e2.png",
"preview_url": "http://mitra/media/e5aa4cd95e47f0bb320ab0c44d927ef293a104d85d4b801ab39d4760d38385e2.png",
"description": "name"
}
],
"mentions": [
{
"id": "0194e231-607b-c1e5-c5c3-2ce84c557b8b",
"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": 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/actor/3YZPYQhtO5k",
"published": "2025-02-07T20:57:41Z",
"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/VwGwi8ou0TA",
"published": "2025-02-07T20:57:41Z",
"content": "text",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
misskey
{
"id": "a3yt0plspl2g0019",
"createdAt": "2025-02-07T20:49:40.000Z",
"userId": "a3ysz1b3pl2g0002",
"user": {
"id": "a3ysz1b3pl2g0002",
"name": "Test Actor",
"username": "actor",
"host": "pasture-one-actor",
"avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
"avatarBlurhash": null,
"avatarDecorations": [],
"isBot": false,
"isCat": false,
"instance": {
"name": null,
"softwareName": null,
"softwareVersion": null,
"iconUrl": null,
"faviconUrl": null,
"themeColor": null
},
"emojis": {},
"onlineStatus": "unknown"
},
"text": "text",
"cw": null,
"visibility": "public",
"localOnly": false,
"reactionAcceptance": null,
"renoteCount": 0,
"repliesCount": 0,
"reactionCount": 0,
"reactions": {},
"reactionEmojis": {},
"emojis": {},
"fileIds": [
"a3yt0q7hpl2g0018"
],
"files": [
{
"id": "a3yt0q7hpl2g0018",
"createdAt": "2025-02-07T20:49:40.781Z",
"name": "FediverseLogo.png",
"type": "image/png",
"md5": "85e7feae66363e9e200570a28b0cf20a",
"size": 0,
"isSensitive": false,
"blurhash": "eQE_?c.}4.YJM^}fi{EVw[xu9JK[M~xI-T9+TJRPX2$$E]NFo}j1tO",
"properties": {
"width": 1548,
"height": 1548
},
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"thumbnailUrl": "http://pasture-one-actor/assets/FediverseLogo.png",
"comment": "name",
"folderId": null,
"folder": null,
"userId": "a3ysz1b3pl2g0002",
"user": null
}
],
"replyId": null,
"renoteId": null,
"uri": "http://pasture-one-actor/actor/VX5S8bTpetM",
"clippedCount": 0
}
mitra
{
"id": "0194e234-4281-6839-3cab-06e2055b50ee",
"uri": "http://pasture-one-actor/actor/VwGwi8ou0TA",
"url": "http://pasture-one-actor/actor/VwGwi8ou0TA",
"created_at": "2025-02-07T20:57:41Z",
"edited_at": null,
"account": {
"id": "0194e232-b067-124b-0799-4ade30ddd9a9",
"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": "2025-02-07T20:56:00.359685Z",
"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": 32,
"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,
"poll": null,
"media_attachments": [
{
"id": "0194e234-427c-e84b-9423-e05a8905829c",
"type": "image",
"url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"description": "name"
}
],
"mentions": [
{
"id": "0194e231-607b-c1e5-c5c3-2ce84c557b8b",
"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": 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/actor/A6eFWZqR0TI",
"published": "2025-02-07T20:57:43Z",
"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/58-IC0AEN_8",
"published": "2025-02-07T20:57:43Z",
"content": "no comment in attachment",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
misskey
{
"id": "a3yt0qdkpl2g001a",
"createdAt": "2025-02-07T20:49:41.000Z",
"userId": "a3ysz1b3pl2g0002",
"user": {
"id": "a3ysz1b3pl2g0002",
"name": "Test Actor",
"username": "actor",
"host": "pasture-one-actor",
"avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
"avatarBlurhash": null,
"avatarDecorations": [],
"isBot": false,
"isCat": false,
"instance": {
"name": null,
"softwareName": null,
"softwareVersion": null,
"iconUrl": null,
"faviconUrl": null,
"themeColor": null
},
"emojis": {},
"onlineStatus": "unknown"
},
"text": "no comment in attachment",
"cw": null,
"visibility": "public",
"localOnly": false,
"reactionAcceptance": null,
"renoteCount": 0,
"repliesCount": 0,
"reactionCount": 0,
"reactions": {},
"reactionEmojis": {},
"emojis": {},
"fileIds": [
"a3yt0q7hpl2g0018"
],
"files": [
{
"id": "a3yt0q7hpl2g0018",
"createdAt": "2025-02-07T20:49:40.781Z",
"name": "FediverseLogo.png",
"type": "image/png",
"md5": "85e7feae66363e9e200570a28b0cf20a",
"size": 0,
"isSensitive": false,
"blurhash": "eQE_?c.}4.YJM^}fi{EVw[xu9JK[M~xI-T9+TJRPX2$$E]NFo}j1tO",
"properties": {
"width": 1548,
"height": 1548
},
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"thumbnailUrl": "http://pasture-one-actor/assets/FediverseLogo.png",
"comment": "name",
"folderId": null,
"folder": null,
"userId": "a3ysz1b3pl2g0002",
"user": null
}
],
"replyId": null,
"renoteId": null,
"uri": "http://pasture-one-actor/actor/-5woXLD-ntM",
"clippedCount": 0
}
mitra
{
"id": "0194e234-485c-47ea-6101-279bf20b3fdd",
"uri": "http://pasture-one-actor/actor/58-IC0AEN_8",
"url": "http://pasture-one-actor/actor/58-IC0AEN_8",
"created_at": "2025-02-07T20:57:43Z",
"edited_at": null,
"account": {
"id": "0194e232-b067-124b-0799-4ade30ddd9a9",
"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": "2025-02-07T20:56:00.359685Z",
"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": 33,
"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,
"poll": null,
"media_attachments": [
{
"id": "0194e234-4854-4b29-89a0-cee508c6ff29",
"type": "image",
"url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"preview_url": "http://mitra/media/2d7a61d31393a44edf2a30160cdd70b3582a4f97d5b550f8141dfee1641b4ae7.png",
"description": null
}
],
"mentions": [
{
"id": "0194e231-607b-c1e5-c5c3-2ce84c557b8b",
"username": "admin",
"acct": "admin",
"url": "http://mitra/users/admin"
}
],
"tags": [],
"emojis": [],
"favourited": false,
"reblogged": false,
"bookmarked": false,
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