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# VNRequestRevisionProviding

A protocol for specifying the revision number of Vision algorithms.

```
protocol VNRequestRevisionProviding
```

## Overview

Subclasses of [`VNRequest`](/documentation/Vision/VNRequest) should adopt this protocol to specify which revision of an algorithm the Vision framework uses to generate requests.

## Topics

### Specifying Revision Number

[`requestRevision`](/documentation/Vision/VNRequestRevisionProviding/requestRevision)

The revision of the [`VNRequest`](/documentation/Vision/VNRequest) subclass used to generate the implementing object.

### Determining Revision Type

[`VNRequestRevisionUnspecified`](/documentation/Vision/VNRequestRevisionUnspecified)

A constant for specifying an unspecified request revision.

[`VNDetectRectanglesRequestRevision1`](/documentation/Vision/VNDetectRectanglesRequestRevision1)

A constant for specifying revision 1 of the rectangle detection request.

[`VNTrackRectangleRequestRevision1`](/documentation/Vision/VNTrackRectangleRequestRevision1)

A constant for specifying revision 1 of the rectangling tracking request.

[`VNTrackObjectRequestRevision1`](/documentation/Vision/VNTrackObjectRequestRevision1)

A constant for specifying revision 1 of the object tracking request.

[`VNDetectFaceRectanglesRequestRevision2`](/documentation/Vision/VNDetectFaceRectanglesRequestRevision2)

A constant for specifying revision 2 of the face rectangles detection request.

[`VNDetectFaceRectanglesRequestRevision1`](/documentation/Vision/VNDetectFaceRectanglesRequestRevision1)

A constant for specifying revision 1 of the face rectangles detection request.

[`VNDetectFaceLandmarksRequestRevision3`](/documentation/Vision/VNDetectFaceLandmarksRequestRevision3)

A constant for specifying revision 3 of the face landmarks detection request.

[`VNDetectFaceLandmarksRequestRevision2`](/documentation/Vision/VNDetectFaceLandmarksRequestRevision2)

A constant for specifying revision 2 of the face landmarks detection request.

[`VNDetectFaceLandmarksRequestRevision1`](/documentation/Vision/VNDetectFaceLandmarksRequestRevision1)

A constant for specifying revision 1 of the face landmarks detection request.

[`VNRecognizeTextRequestRevision1`](/documentation/Vision/VNRecognizeTextRequestRevision1)

A constant for specifying revision 1 of the text recognition request.

[`VNDetectTextRectanglesRequestRevision1`](/documentation/Vision/VNDetectTextRectanglesRequestRevision1)

A constant for specifying revision 1 of the text rectangles detection request.

[`VNDetectBarcodesRequestRevision1`](/documentation/Vision/VNDetectBarcodesRequestRevision1)

A constant for specifying revision 1 of the barcode detection request.

[`VNDetectHorizonRequestRevision1`](/documentation/Vision/VNDetectHorizonRequestRevision1)

A constant for specifying revision 1 of the horizon detection request.

[`VNTranslationalImageRegistrationRequestRevision1`](/documentation/Vision/VNTranslationalImageRegistrationRequestRevision1)

A constant for specifying revision 1 of the translational image registration request.

[`VNHomographicImageRegistrationRequestRevision1`](/documentation/Vision/VNHomographicImageRegistrationRequestRevision1)

A constant for specifying revision 1 of the homographic image registration request.

[`VNCoreMLRequestRevision1`](/documentation/Vision/VNCoreMLRequestRevision1)

A constant for specifying revision 1 of a Core ML request.

[`VNGenerateAttentionBasedSaliencyImageRequestRevision1`](/documentation/Vision/VNGenerateAttentionBasedSaliencyImageRequestRevision1)

A constant for specifying revision 1 of the image saliency request.

[`VNGenerateObjectnessBasedSaliencyImageRequestRevision1`](/documentation/Vision/VNGenerateObjectnessBasedSaliencyImageRequestRevision1)

A constant for specifying revision 1 of the image saliency request.

[`VNClassifyImageRequestRevision1`](/documentation/Vision/VNClassifyImageRequestRevision1)

A constant for specifying the first revision of the image-classification request.

[`VNGenerateImageFeaturePrintRequestRevision1`](/documentation/Vision/VNGenerateImageFeaturePrintRequestRevision1)

A constant for specifying the first revision of the feature-print request.

[`VNDetectFaceCaptureQualityRequestRevision1`](/documentation/Vision/VNDetectFaceCaptureQualityRequestRevision1)

A constant for specifying revision 1 of the face capture detection request.

[`VNDetectHumanRectanglesRequestRevision1`](/documentation/Vision/VNDetectHumanRectanglesRequestRevision1)

A constant for specifying revision 1 of the human rectangles detection request.


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