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ARCore lets you useArImageMetadatato access metadata key values from the camera image capture result. Some
common types of camera image metadata you might want to access are focal length,
image timestamp data, or lighting information.
The AndroidCameramodule can record 160 or more parameters about the image
for each frame captured, depending on a device's capabilities. For a list of all
possible metadata keys, see theNDKCameradocumentation.
Get the value of an individual metadata tag
UseArImageMetadata_getConstEntry()to get a specific metadata tag value. The following example shows obtaining theACAMERA_SENSOR_EXPOSURE_TIMEmetadata value:
ArSession_update(session,frame);// Obtain the metadata object from the frame.ArImageMetadata*ar_metadata;ArFrame_acquireImageMetadata(session,frame,&ar_metadata);// Get the exposure time metadata (using ACAMERA_SENSOR_EXPOSURE_TIME in this// example).ArImageMetadata_const_entryexposure_entry;ArImageMetadata_getConstEntry(session,ar_metadata,ACAMERA_SENSOR_EXPOSURE_TIME,&exposure_entry);
ArSession_update(session,frame);// Obtain the metadata object from the frame.ArImageMetadata*ar_metadata;ArFrame_acquireImageMetadata(session,frame,&ar_metadata);// Obtain the list of all the metadata for a given frame.constuint32_t*all_tags=NULL;int32_tnumber_of_tags=-1;ArImageMetadata_getAllKeys(session,ar_metadata,&number_of_tags,&all_tags);
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2024-10-31 UTC."],[[["\u003cp\u003eARCore's \u003ccode\u003eArImageMetadata\u003c/code\u003e allows access to camera image metadata like focal length, timestamps, and lighting information.\u003c/p\u003e\n"],["\u003cp\u003eDevelopers can retrieve specific metadata values, such as exposure time, using \u003ccode\u003eArImageMetadata_getConstEntry()\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eArImageMetadata_getAllKeys()\u003c/code\u003e provides a list of all metadata tags available for a given frame.\u003c/p\u003e\n"],["\u003cp\u003eThe Android \u003ccode\u003eCamera\u003c/code\u003e module can record extensive image parameters, with a full list available in the NDK documentation.\u003c/p\u003e\n"]]],[],null,["# Camera image metadata\n\nARCore lets you use [`ArImageMetadata`](/ar/reference/c/group/ar-image-metadata)\nto access metadata key values from the camera image capture result. Some\ncommon types of camera image metadata you might want to access are focal length,\nimage timestamp data, or lighting information.\n\nThe Android `Camera` module can record 160 or more parameters about the image\nfor each frame captured, depending on a device's capabilities. For a list of all\npossible metadata keys, see the [NDK `Camera` documentation](https://developer.android.com/ndk/reference/group/camera).\n\nGet the value of an individual metadata tag\n-------------------------------------------\n\nUse [`ArImageMetadata_getConstEntry()`](/ar/reference/c/group/ar-image-metadata#arimagemetadata_getconstentry)\nto get a specific metadata tag value. The following example shows obtaining the `ACAMERA_SENSOR_EXPOSURE_TIME` metadata value: \n\n```c\nArSession_update(session, frame);\n\n// Obtain the metadata object from the frame.\nArImageMetadata* ar_metadata;\nArFrame_acquireImageMetadata(session, frame, &ar_metadata);\n\n// Get the exposure time metadata (using ACAMERA_SENSOR_EXPOSURE_TIME in this\n// example).\nArImageMetadata_const_entry exposure_entry;\nArImageMetadata_getConstEntry(session, ar_metadata,\n ACAMERA_SENSOR_EXPOSURE_TIME, &exposure_entry);\n```\n\nGet a list of all metadata tags for a given frame\n-------------------------------------------------\n\nUse [`ArImageMetadata_getAllKeys()`](/ar/reference/c/group/ar-image-metadata#arimagemetadata_getallkeys) to get a list of all metadata keys captured\nfor a given frame. \n\n```c\nArSession_update(session, frame);\n\n// Obtain the metadata object from the frame.\nArImageMetadata* ar_metadata;\nArFrame_acquireImageMetadata(session, frame, &ar_metadata);\n\n// Obtain the list of all the metadata for a given frame.\nconst uint32_t* all_tags = NULL;\nint32_t number_of_tags = -1;\n\nArImageMetadata_getAllKeys(session, ar_metadata, &number_of_tags, &all_tags);\n```"]]
