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": [
"http://mastodon/users/hippo",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/actor/gxvngwciiAY",
"published": "2025-02-27T19:36:30Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://mastodon/users/hippo"
],
"id": "http://pasture-one-actor/actor/YiF4Z_blX18",
"published": "2025-02-27T19:36:30Z",
"content": "no description",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png"
}
}
}
mastodon
{
"id": "114077531543576724",
"created_at": "2025-02-27T19:36:30.000Z",
"in_reply_to_id": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": null,
"uri": "http://pasture-one-actor/actor/YiF4Z_blX18",
"url": "http://pasture-one-actor/actor/YiF4Z_blX18",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"edited_at": null,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "no description",
"filtered": [],
"reblog": null,
"account": {
"id": "114077523922167961",
"username": "actor",
"acct": "actor@pasture-one-actor",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": false,
"indexable": false,
"group": false,
"created_at": "2025-02-27T00:00:00.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"uri": "http://pasture-one-actor/actor",
"avatar": "http://mastodon/avatars/original/missing.png",
"avatar_static": "http://mastodon/avatars/original/missing.png",
"header": "http://mastodon/headers/original/missing.png",
"header_static": "http://mastodon/headers/original/missing.png",
"followers_count": 0,
"following_count": 0,
"statuses_count": 32,
"last_status_at": "2025-02-27",
"hide_collections": true,
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "114077531534666091",
"type": "image",
"url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/534/666/091/original/5eb9f94813432afb.png",
"preview_url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/534/666/091/small/5eb9f94813432afb.png",
"remote_url": "http://pasture-one-actor/images/100.png",
"preview_remote_url": null,
"text_url": null,
"meta": {
"original": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1.0
},
"small": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1.0
}
},
"description": null,
"blurhash": "U2Rh8R|zfQ|z|zjtfQjtfQfQfQfQ|zjtfQjt"
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null
}
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://mastodon/users/hippo",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/actor/DOxtw0iv3A0",
"published": "2025-02-27T19:36:31Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://mastodon/users/hippo"
],
"id": "http://pasture-one-actor/actor/sdJdsM6pVQY",
"published": "2025-02-27T19:36:31Z",
"content": "text",
"attachment": {
"type": "Document",
"url": "http://pasture-one-actor/images/100.png",
"name": "name",
"summary": "summary",
"content": "content"
}
}
}
mastodon
{
"id": "114077531610557126",
"created_at": "2025-02-27T19:36:31.000Z",
"in_reply_to_id": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": null,
"uri": "http://pasture-one-actor/actor/sdJdsM6pVQY",
"url": "http://pasture-one-actor/actor/sdJdsM6pVQY",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"edited_at": null,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "text",
"filtered": [],
"reblog": null,
"account": {
"id": "114077523922167961",
"username": "actor",
"acct": "actor@pasture-one-actor",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": false,
"indexable": false,
"group": false,
"created_at": "2025-02-27T00:00:00.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"uri": "http://pasture-one-actor/actor",
"avatar": "http://mastodon/avatars/original/missing.png",
"avatar_static": "http://mastodon/avatars/original/missing.png",
"header": "http://mastodon/headers/original/missing.png",
"header_static": "http://mastodon/headers/original/missing.png",
"followers_count": 0,
"following_count": 0,
"statuses_count": 33,
"last_status_at": "2025-02-27",
"hide_collections": true,
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "114077531598513661",
"type": "image",
"url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/598/513/661/original/4a6c100ca4d2baf5.png",
"preview_url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/598/513/661/small/4a6c100ca4d2baf5.png",
"remote_url": "http://pasture-one-actor/images/100.png",
"preview_remote_url": null,
"text_url": null,
"meta": {
"original": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1.0
},
"small": {
"width": 40,
"height": 40,
"size": "40x40",
"aspect": 1.0
}
},
"description": "summary",
"blurhash": "U0B6q4.ifQ.i.ij@fQj@fQfQfQfQ.ij@fQj@"
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null
}
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://mastodon/users/hippo",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/actor/XOfA0MVD_ik",
"published": "2025-02-27T19:36:32Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://mastodon/users/hippo"
],
"id": "http://pasture-one-actor/actor/PC1jmL1hqAo",
"published": "2025-02-27T19:36:32Z",
"content": "text",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png",
"name": "name",
"imageType": "image/jpeg"
}
]
}
}
mastodon
{
"id": "114077531674949066",
"created_at": "2025-02-27T19:36:32.000Z",
"in_reply_to_id": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": null,
"uri": "http://pasture-one-actor/actor/PC1jmL1hqAo",
"url": "http://pasture-one-actor/actor/PC1jmL1hqAo",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"edited_at": null,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "text",
"filtered": [],
"reblog": null,
"account": {
"id": "114077523922167961",
"username": "actor",
"acct": "actor@pasture-one-actor",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": false,
"indexable": false,
"group": false,
"created_at": "2025-02-27T00:00:00.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"uri": "http://pasture-one-actor/actor",
"avatar": "http://mastodon/avatars/original/missing.png",
"avatar_static": "http://mastodon/avatars/original/missing.png",
"header": "http://mastodon/headers/original/missing.png",
"header_static": "http://mastodon/headers/original/missing.png",
"followers_count": 0,
"following_count": 0,
"statuses_count": 34,
"last_status_at": "2025-02-27",
"hide_collections": true,
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "114077531662884268",
"type": "image",
"url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/662/884/268/original/85f0ea811df8600f.png",
"preview_url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/662/884/268/small/85f0ea811df8600f.png",
"remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
"preview_remote_url": null,
"text_url": null,
"meta": {
"original": {
"width": 1548,
"height": 1548,
"size": "1548x1548",
"aspect": 1.0
},
"small": {
"width": 480,
"height": 480,
"size": "480x480",
"aspect": 1.0
}
},
"description": "name",
"blurhash": "UOEVB2.}4.T=}fjEEVw[4=K[RUw~9,TJV?bW"
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null
}
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://mastodon/users/hippo",
"https://www.w3.org/ns/activitystreams#Public"
],
"id": "http://pasture-one-actor/actor/otNYfhhFgm8",
"published": "2025-02-27T19:36:33Z",
"object": {
"type": "Note",
"attributedTo": "http://pasture-one-actor/actor",
"to": [
"https://www.w3.org/ns/activitystreams#Public",
"http://mastodon/users/hippo"
],
"id": "http://pasture-one-actor/actor/SotaXbSfPz4",
"published": "2025-02-27T19:36:33Z",
"content": "no comment in attachment",
"attachment": [
{
"type": "Document",
"url": "http://pasture-one-actor/assets/FediverseLogo.png"
}
]
}
}
mastodon
{
"id": "114077531739724248",
"created_at": "2025-02-27T19:36:33.000Z",
"in_reply_to_id": null,
"in_reply_to_account_id": null,
"sensitive": false,
"spoiler_text": "",
"visibility": "public",
"language": null,
"uri": "http://pasture-one-actor/actor/SotaXbSfPz4",
"url": "http://pasture-one-actor/actor/SotaXbSfPz4",
"replies_count": 0,
"reblogs_count": 0,
"favourites_count": 0,
"edited_at": null,
"favourited": false,
"reblogged": false,
"muted": false,
"bookmarked": false,
"content": "no comment in attachment",
"filtered": [],
"reblog": null,
"account": {
"id": "114077523922167961",
"username": "actor",
"acct": "actor@pasture-one-actor",
"display_name": "Test Actor",
"locked": false,
"bot": false,
"discoverable": false,
"indexable": false,
"group": false,
"created_at": "2025-02-27T00:00:00.000Z",
"note": "",
"url": "http://pasture-one-actor/actor",
"uri": "http://pasture-one-actor/actor",
"avatar": "http://mastodon/avatars/original/missing.png",
"avatar_static": "http://mastodon/avatars/original/missing.png",
"header": "http://mastodon/headers/original/missing.png",
"header_static": "http://mastodon/headers/original/missing.png",
"followers_count": 0,
"following_count": 0,
"statuses_count": 35,
"last_status_at": "2025-02-27",
"hide_collections": true,
"emojis": [],
"fields": []
},
"media_attachments": [
{
"id": "114077531727099815",
"type": "image",
"url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/727/099/815/original/e35defa8f5fda40c.png",
"preview_url": "http://localhost:2970/system/cache/media_attachments/files/114/077/531/727/099/815/small/e35defa8f5fda40c.png",
"remote_url": "http://pasture-one-actor/assets/FediverseLogo.png",
"preview_remote_url": null,
"text_url": null,
"meta": {
"original": {
"width": 1548,
"height": 1548,
"size": "1548x1548",
"aspect": 1.0
},
"small": {
"width": 480,
"height": 480,
"size": "480x480",
"aspect": 1.0
}
},
"description": null,
"blurhash": "UOEVB2.}4.T=}fjEEVw[4=K[RUw~9,TJV?bW"
}
],
"mentions": [],
"tags": [],
"emojis": [],
"card": null,
"poll": null
}