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# CIRectangleFeature

Information about a rectangular region detected in a still or video image.

```
class CIRectangleFeature
```

## Overview> Note: In macOS 10.13, iOS 11, and tvOS 11 or later, the Vision framework replaces these classes
> for identifying and analyzing image features.
> See <doc://com.apple.documentation/documentation/Vision/VNDetectFaceRectanglesRequest>)

A detected rectangle feature is not necessarily rectangular in the plane of the image; rather, the
feature identifies a shape that may be rectangular in space (for example a book on a desk) but which
appears as a four-sided polygon in the image. The properties of a `CIRectangleFeature` object
identify its four corners in image coordinates.

You can use rectangle feature detection together with the `CIPerspectiveCorrection` filter
to transform the feature to a normal orientation.

To detect rectangles in an image or video, choose [`CIDetectorTypeRectangle`](/documentation/CoreImage/CIDetectorTypeRectangle) when initializing a
[`CIDetector`](/documentation/CoreImage/CIDetector) object, and use the `CIDetectorAspectRatio` and `CIDetectorFocalLength` options to
specify the approximate shape of rectangular features to search for. The detector returns at
most one rectangle feature, the most prominent found in the image.

## Topics

### Locating a Detected Feature

[`bounds`](/documentation/CoreImage/CIRectangleFeature/bounds-swift.property)

A rectangle indicating the position and extent of the feature in image coordinates.

### Identifying the Corners of a Detected Rectangle

[`bottomLeft`](/documentation/CoreImage/CIRectangleFeature/bottomLeft-swift.property)

The lower-left corner of the detected rectangle, in image coordinates.

[`bottomRight`](/documentation/CoreImage/CIRectangleFeature/bottomRight-swift.property)

The lower-right corner of the detected rectangle, in image coordinates.

[`topLeft`](/documentation/CoreImage/CIRectangleFeature/topLeft-swift.property)

The upper-left corner of the detected rectangle, in image coordinates.

[`topRight`](/documentation/CoreImage/CIRectangleFeature/topRight-swift.property)

The upper-right corner of the detected rectangle, in image coordinates.


---

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