matrix-spec/event-schemas/schema/m.room.message#m.image

{
    "type": "object",
    "title": "ImageMessage",
    "description": "This message represents a single image and an optional thumbnail.",
    "allOf": [{
        "$ref": "core-event-schema/room_event.json"
    }],
    "properties": {
        "content": {
            "type": "object",
            "properties": {
                "msgtype": {
                    "type": "string",
                    "enum": ["m.image"]
                },
                "body": {
                    "type": "string",
                    "description": "A textual representation of the image. This could be the alt text of the image, the filename of the image, or some kind of content description for accessibility e.g. 'image attachment'."
                },
                "url": {
                    "type": "string",
                    "description": "The URL to the image."
                },
                "thumbnail_url": {
                    "type": "string",
                    "description": "The URL to the thumbnail of the image."
                },
                "thumbnail_info": {
                    "type": "object",
                    "title": "ImageInfo",
                    "description": "Metadata about the image referred to in ``thumbnail_url``.",
                    "allOf": [{
                        "$ref": "core-event-schema/msgtype_infos/image_info.json"
                    }]
                },
                "info": {
                    "type": "object",
                    "title": "ImageInfo",
                    "description": "Metadata about the image referred to in ``url``.",
                    "properties": {
                        "size": {
                            "type": "integer",
                            "description": "Size of the image in bytes."
                        },
                        "w": {
                            "type": "integer",
                            "description": "The width of the image in pixels."
                        },
                        "h": {
                            "type": "integer",
                            "description": "The height of the image in pixels."
                        },
                        "mimetype": {
                            "type": "string",
                            "description": "The mimetype of the image, e.g. ``image/jpeg``."
                        }
                    }
                }
            },
            "required": ["msgtype", "body", "url"]
        },
        "type": {
            "type": "string",
            "enum": ["m.room.message"]
        }
    }
}