face freshness

Author: PatrickFarley

articles/cognitive-services/Face/concepts/face-detection.md

@@ -1,15 +1,15 @@
 ---
 title: "Face detection and attributes concepts"
 titleSuffix: Azure Cognitive Services
-description: Face detection is the action of locating human faces in an image and optionally returning different kinds of face-related data.
+description: Learn more about face detection; face detection is the action of locating human faces in an image and optionally returning different kinds of face-related data.
 services: cognitive-services
 author: PatrickFarley
 manager: nitime
 
 ms.service: cognitive-services
 ms.subservice: face-api
 ms.topic: conceptual
-ms.date: 04/26/2019
+ms.date: 10/27/2021
 ms.author: pafarley
 ---
 
@@ -62,18 +62,27 @@ Attributes are a set of features that can optionally be detected by the [Face -
 
 Use the following tips to make sure that your input images give the most accurate detection results:
 
-* The supported input image formats are JPEG, PNG, GIF for the first frame, and BMP.
+* The supported input image formats are JPEG, PNG, GIF (the first frame), BMP. 
 * The image file size should be no larger than 6 MB.
 * The minimum detectable face size is 36 x 36 pixels in an image that is no larger than 1920 x 1080 pixels. Images with larger than 1920 x 1080 pixels have a proportionally larger minimum face size. Reducing the face size might cause some faces not to be detected, even if they are larger than the minimum detectable face size.
 * The maximum detectable face size is 4096 x 4096 pixels.
 * Faces outside the size range of 36 x 36 to 4096 x 4096 pixels will not be detected.
-* Some faces might not be detected because of technical challenges. Extreme face angles (head pose) or face occlusion (objects such as sunglasses or hands that block part of the face) can affect detection. Frontal and near-frontal faces give the best results.
+* Some faces might not be recognized because of technical challenges, such as:
+  * Images with extreme lighting, for example, severe backlighting.
+  * Obstructions that block one or both eyes.
+  * Differences in hair type or facial hair.
+  * Changes in facial appearance because of age.
+  * Extreme facial expressions.
 
-Input data with orientation information:
-* Some input images with JPEG format might contain orientation information in Exchangeable image file format (Exif) metadata. If Exif orientation is available, images will be automatically rotated to the correct orientation before sending for face detection. The face rectangle, landmarks, and head pose for each detected face will be estimated based on the rotated image.
-* To properly display the face rectangle and landmarks, you need to make sure the image is rotated correctly. Most of image visualization tools will auto-rotate the image according to its Exif orientation by default. For other tools, you might need to apply the rotation using your own code. The following examples show a face rectangle on a rotated image (left) and a non-rotated image (right).
+### Input data with orientation information:
 
-![Two face images with/without rotation](../Images/image-rotation.png)
+Some input images with JPEG format might contain orientation information in Exchangeable image file format (Exif) metadata. If Exif orientation is available, images will be automatically rotated to the correct orientation before sending for face detection. The face rectangle, landmarks, and head pose for each detected face will be estimated based on the rotated image.
+
+To properly display the face rectangle and landmarks, you need to make sure the image is rotated correctly. Most of image visualization tools will auto-rotate the image according to its Exif orientation by default. For other tools, you might need to apply the rotation using your own code. The following examples show a face rectangle on a rotated image (left) and a non-rotated image (right).
+
+![Two face images with and without rotation](../Images/image-rotation.png)
+
+### Video input
 
 If you're detecting faces from a video feed, you may be able to improve performance by adjusting certain settings on your video camera:
 

articles/cognitive-services/Face/concepts/face-recognition.md

@@ -1,25 +1,27 @@
 ---
 title: "Face recognition concepts"
 titleSuffix: Azure Cognitive Services
-description: This article explains the concept of Face recognition, its related operations, and the underlying data structures.
+description: Learn the concept of Face recognition, its related operations, and the underlying data structures.
 services: cognitive-services
 author: PatrickFarley
 manager: nitime
 
 ms.service: cognitive-services
 ms.subservice: face-api
 ms.topic: conceptual
-ms.date: 04/23/2019
+ms.date: 10/27/2021
 ms.author: pafarley
 ---
 
 # Face recognition concepts
 
-This article explains the concept of Face recognition, its related operations, and the underlying data structures. Broadly, Face recognition refers to the method of verifying or identifying an individual using their face. Verification is one-to-one matching that takes two faces and returns whether they are the same face, and identification is one-to-many matching that takes a single face as input and returns a set of matching candidates. Face recognition is important in implementing the identity verification scenario, which enterprises and apps use to verify that a (remote) user is who they claim to be.
+This article explains the concept of Face recognition, its related operations, and the underlying data structures. Broadly, Face recognition refers to the method of verifying or identifying an individual by their face. 
+
+Verification is one-to-one matching that takes two faces and returns whether they are the same face, and identification is one-to-many matching that takes a single face as input and returns a set of matching candidates. Face recognition is important in implementing the identity verification scenario, which enterprises and apps can use to verify that a (remote) user is who they claim to be.
 
 ## Related data structures
 
-The recognition operations use mainly the following data structures. These objects are stored in the cloud and can be referenced by their ID strings. ID strings are always unique within a subscription. Name fields may be duplicated.
+The recognition operations use mainly the following data structures. These objects are stored in the cloud and can be referenced by their ID strings. ID strings are always unique within a subscription, but name fields may be duplicated.
 
 |Name|Description|
 |:--|:--|
@@ -28,10 +30,11 @@ The recognition operations use mainly the following data structures. These objec
 |[FaceList](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/563879b61984550f3039524b) or [LargeFaceList](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/5a157b68d2de3616c086f2cc)| This data structure is an assorted list of PersistedFace objects. A FaceList has a unique ID, a name string, and optionally a user data string.|
 |[Person](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/563879b61984550f3039523c)| This data structure is a list of PersistedFace objects that belong to the same person. It has a unique ID, a name string, and optionally a user data string.|
 |[PersonGroup](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/563879b61984550f30395244) or [LargePersonGroup](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/599acdee6ac60f11b48b5a9d)| This data structure is an assorted list of Person objects. It has a unique ID, a name string, and optionally a user data string. A PersonGroup must be [trained](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/563879b61984550f30395249) before it can be used in recognition operations.|
+|PersonDirectory | This data structure is like **LargePersonGroup** but offers additional storage capacity and other added features. For more information, see [Use the PersonDirectory structure](Face-API-How-to-Topics/use-persondirectory.md).
 
 ## Recognition operations
 
-This section details how the underlying operations use the data structures previously described to identify and verify a face.
+This section details how the underlying operations use the above data structures to identify and verify a face.
 
 ### PersonGroup creation and training
 
@@ -43,12 +46,10 @@ The [Train](https://westus.dev.cognitive.microsoft.com/docs/services/563879b6198
 
 The [Identify](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/563879b61984550f30395239) operation takes one or several source face IDs (from a DetectedFace or PersistedFace object) and a PersonGroup or LargePersonGroup. It returns a list of the Person objects that each source face might belong to. Returned Person objects are wrapped as Candidate objects, which have a prediction confidence value.
 
-
 ### Verification
 
 The [Verify](https://westus.dev.cognitive.microsoft.com/docs/services/563879b61984550e40cbbe8d/operations/563879b61984550f3039523a) operation takes a single face ID (from a DetectedFace or PersistedFace object) and a Person object. It determines whether the face belongs to that same person. Verification is one-to-one matching and can be used as a final check on the results from the Identify API call. However, you can optionally pass in the PersonGroup to which the candidate Person belongs to improve the API performance.
 
-
 ## Input data
 
 Use the following tips to ensure that your input images give the most accurate recognition results:

articles/cognitive-services/Face/index.yml

@@ -11,7 +11,7 @@ metadata:
   ms.topic: landing-page
   author: PatrickFarley
   ms.author: pafarley
-  ms.date: 9/01/2020
+  ms.date: 10/27/2021
 
 
 # linkListType: architecture | concept | deploy | download | get-started | how-to-guide | learn | overview | quickstart | reference | tutorial | video | whats-new
@@ -31,8 +31,6 @@ landingContent:
           - text: What's new in Face service?
             url: releasenotes.md
 
-  
-
   - title: Face recognition
     linkLists:
       - linkListType: concept