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://friendica/profile/friend",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/oR8ovip1yb0",
"published": "2025-09-06T15:09:36Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://friendica/profile/friend"
],
"id": "http://pasture-one-actor/object/qgrrHTtaJWY",
"published": "2025-09-06T15:09:36Z",
"content": "no description",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png"
}
}
}
friendica
{
"id": "66",
"created_at": "2025-09-06T15:09:36.000Z",
"edited_at": null,
"in_reply_to_id": null,
"in_reply_to_status": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": "fr",
"uri": "http://pasture-one-actor/object/qgrrHTtaJWY",
"url": "http://pasture-one-actor/object/qgrrHTtaJWY",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "no description",
"reblog": null,
"quote": null,
"application": {
"name": "ActivityPub",
"vapid_key": null
},
"account": {
"id": "5",
"username": "actor",
"acct": "",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": true,
"group": false,
"created_at": "2025-09-06T15:04:52.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"avatar": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"avatar_static": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"header": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"header_static": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"followers_count": 0,
"following_count": 0,
"statuses_count": 0,
"last_status_at": "2025-09-06T00:00:00.000Z",
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "9",
"type": "image",
"url": "http://friendica/photo/preview/9",
"preview_url": "http://friendica/photo/preview/640/9",
"remote_url": "http://pasture-one-actor/images/100.png",
"text_url": "http://pasture-one-actor/images/100.png",
"description": null,
"blurhash": "|5Ol{F}afQ}afQ}afQ}afQ}aj[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ}aj[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ}aj[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ}aj[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ",
"meta": {
"original": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1
}
}
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null,
"friendica": {
"title": "",
"changed_at": "2025-09-06T15:09:36.000Z",
"commented_at": "2025-09-06T15:09:36.000Z",
"received_at": "2025-09-06T15:09:36.000Z",
"delivery_data": {
"delivery_queue_count": null,
"delivery_queue_done": null,
"delivery_queue_failed": null
},
"dislikes_count": 0,
"disliked": false,
"network": "ActivityPub",
"platform": "ActivityPub",
"version": "",
"sitename": "",
"visibility": {
"allow_cid": [],
"deny_cid": [],
"allow_gid": [],
"deny_gid": []
},
"content": "no description"
}
}
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://friendica/profile/friend",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/I-Z27Mm4Z2g",
"published": "2025-09-06T15:09:38Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://friendica/profile/friend"
],
"id": "http://pasture-one-actor/object/L-TmXMrWaWE",
"published": "2025-09-06T15:09:38Z",
"content": "text",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
friendica
{
"id": "67",
"created_at": "2025-09-06T15:09:38.000Z",
"edited_at": null,
"in_reply_to_id": null,
"in_reply_to_status": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": "gl",
"uri": "http://pasture-one-actor/object/L-TmXMrWaWE",
"url": "http://pasture-one-actor/object/L-TmXMrWaWE",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "text",
"reblog": null,
"quote": null,
"application": {
"name": "ActivityPub",
"vapid_key": null
},
"account": {
"id": "5",
"username": "actor",
"acct": "",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": true,
"group": false,
"created_at": "2025-09-06T15:04:52.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"avatar": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"avatar_static": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"header": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"header_static": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"followers_count": 0,
"following_count": 0,
"statuses_count": 0,
"last_status_at": "2025-09-06T00:00:00.000Z",
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "11",
"type": "image",
"url": "http://friendica/photo/preview/11",
"preview_url": "http://friendica/photo/preview/640/11",
"remote_url": "http://pasture-one-actor/images/100.png",
"text_url": "http://pasture-one-actor/images/100.png",
"description": "name",
"blurhash": "|5Ftc|%%fQ%%fQ%%fQ%%fQ%%j[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ%%j[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ%%j[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ%%j[fQj[fQj[fQj[fQfQfQfQfQfQfQfQfQfQ",
"meta": {
"original": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1
}
}
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null,
"friendica": {
"title": "",
"changed_at": "2025-09-06T15:09:38.000Z",
"commented_at": "2025-09-06T15:09:38.000Z",
"received_at": "2025-09-06T15:09:38.000Z",
"delivery_data": {
"delivery_queue_count": null,
"delivery_queue_done": null,
"delivery_queue_failed": null
},
"dislikes_count": 0,
"disliked": false,
"network": "ActivityPub",
"platform": "ActivityPub",
"version": "",
"sitename": "",
"visibility": {
"allow_cid": [],
"deny_cid": [],
"allow_gid": [],
"deny_gid": []
},
"content": "text"
}
}
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://friendica/profile/friend",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/4oGuy3Ar4hM",
"published": "2025-09-06T15:09:39Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://friendica/profile/friend"
],
"id": "http://pasture-one-actor/object/i0tiIh0Hn1o",
"published": "2025-09-06T15:09:39Z",
"content": "text",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
friendica
{
"id": "68",
"created_at": "2025-09-06T15:09:39.000Z",
"edited_at": null,
"in_reply_to_id": null,
"in_reply_to_status": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": "gl",
"uri": "http://pasture-one-actor/object/i0tiIh0Hn1o",
"url": "http://pasture-one-actor/object/i0tiIh0Hn1o",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "text",
"reblog": null,
"quote": null,
"application": {
"name": "ActivityPub",
"vapid_key": null
},
"account": {
"id": "5",
"username": "actor",
"acct": "",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": true,
"group": false,
"created_at": "2025-09-06T15:04:52.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"avatar": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"avatar_static": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"header": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"header_static": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"followers_count": 0,
"following_count": 0,
"statuses_count": 0,
"last_status_at": "2025-09-06T00:00:00.000Z",
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "13",
"type": "image",
"url": "http://friendica/photo/preview/13",
"preview_url": "http://friendica/photo/preview/640/13",
"remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
"text_url": "http://pasture-one-actor/assets/FediverseLogo.png",
"description": "name",
"blurhash": "|JDSH{.}0eT?ImEdK5TVi*}fnhEVw[xvRrRQXlW-4rK[N1$S=^VtkW#Co@5cO?ROX2$yR*oa+xs;ARM{tki%t7t9m@tLRktUa7xmrvRhXKNMXRjJwExawPi^I^XSSbRpxsRWxm#kOtI]nlozNGotIwoOxsSbNFn%xsV{V]",
"meta": {
"original": {
"width": 1548,
"height": 1548,
"size": "1548x1548",
"aspect": 1
}
}
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null,
"friendica": {
"title": "",
"changed_at": "2025-09-06T15:09:40.000Z",
"commented_at": "2025-09-06T15:09:40.000Z",
"received_at": "2025-09-06T15:09:40.000Z",
"delivery_data": {
"delivery_queue_count": null,
"delivery_queue_done": null,
"delivery_queue_failed": null
},
"dislikes_count": 0,
"disliked": false,
"network": "ActivityPub",
"platform": "ActivityPub",
"version": "",
"sitename": "",
"visibility": {
"allow_cid": [],
"deny_cid": [],
"allow_gid": [],
"deny_gid": []
},
"content": "text"
}
}
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://friendica/profile/friend",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/activity/TYNCBrPzFek",
"published": "2025-09-06T15:09:41Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://friendica/profile/friend"
],
"id": "http://pasture-one-actor/object/Zxhk57lccjU",
"published": "2025-09-06T15:09:41Z",
"content": "no comment in attachment",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
friendica
{
"id": "69",
"created_at": "2025-09-06T15:09:41.000Z",
"edited_at": null,
"in_reply_to_id": null,
"in_reply_to_status": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": "ca",
"uri": "http://pasture-one-actor/object/Zxhk57lccjU",
"url": "http://pasture-one-actor/object/Zxhk57lccjU",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "no comment in attachment",
"reblog": null,
"quote": null,
"application": {
"name": "ActivityPub",
"vapid_key": null
},
"account": {
"id": "5",
"username": "actor",
"acct": "",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": true,
"group": false,
"created_at": "2025-09-06T15:04:52.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"avatar": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"avatar_static": "http://friendica/photo/contact/320/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"header": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092",
"header_static": "http://friendica/photo/header/0700725d-72c7be8a-36a431191785fdc7?ts=1757171092&static=1",
"followers_count": 0,
"following_count": 0,
"statuses_count": 0,
"last_status_at": "2025-09-06T00:00:00.000Z",
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "15",
"type": "image",
"url": "http://friendica/photo/preview/15",
"preview_url": "http://friendica/photo/preview/640/15",
"remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
"text_url": "http://pasture-one-actor/assets/FediverseLogo.png",
"description": null,
"blurhash": "|JDSH{.}0eT?ImEdK5TVi*}fnhEVw[xvRrRQXlW-4rK[N1$S=^VtkW#Co@5cO?ROX2$yR*oa+xs;ARM{tki%t7t9m@tLRktUa7xmrvRhXKNMXRjJwExawPi^I^XSSbRpxsRWxm#kOtI]nlozNGotIwoOxsSbNFn%xsV{V]",
"meta": {
"original": {
"width": 1548,
"height": 1548,
"size": "1548x1548",
"aspect": 1
}
}
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null,
"friendica": {
"title": "",
"changed_at": "2025-09-06T15:09:41.000Z",
"commented_at": "2025-09-06T15:09:41.000Z",
"received_at": "2025-09-06T15:09:41.000Z",
"delivery_data": {
"delivery_queue_count": null,
"delivery_queue_done": null,
"delivery_queue_failed": null
},
"dislikes_count": 0,
"disliked": false,
"network": "ActivityPub",
"platform": "ActivityPub",
"version": "",
"sitename": "",
"visibility": {
"allow_cid": [],
"deny_cid": [],
"allow_gid": [],
"deny_gid": []
},
"content": "no comment in attachment"
}
}