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# areaMinMaxRed()

Calculates the minimum and maximum red component value.

```
class func areaMinMaxRed() -> any CIFilter & CIAreaMinMaxRed
```

## Return Value

The generated image.

## Discussion

This method applies the area-minimum-maximum-red filter to an image. This effect calculates the darkest and lightest red color value in the region defined by `extent`. The red and green components of the 1 x 1 pixel output image contain the result.

The area-minimum-maximum-red filter uses the following properties:

- `inputImage`: An image with the type [`CIImage`](/documentation/CoreImage/CIImage).
- `extent`:  A <doc://com.apple.documentation/documentation/CoreFoundation/CGRect> that specifies the subregion of the image that you want to process.

The following code creates a filter that results in a 1 x 1 pixel image with the red and green color components populated:

```swift
func areaMinMaxRed(inputImage: CIImage) -> CIImage {
    let filter = CIFilter.areaMinMaxRed()
    filter.inputImage = inputImage
    filter.extent = CGRect(
        x: inputImage.extent.width/2-250,
        y: inputImage.extent.height/2-250,
        width: 500,
        height: 500)
     return filter.outputImage!
}
```

![Two images arranged horizontally. The left image contains a photograph of three hydrangea flowers with leaves in the background. A 500 x 500 pixel square in the center of the image is highlighted using an outlined box. The image on the right shows the result of applying the area min-max red filter to the 500 x 500 pixel square. The result is a 1 x 1 pixel image containing a green color. This indicates that the 100 x 100 pixel square contains colors that contain a strong red component along with colors that contain a weak red component.](images/com.apple.coreimage/media-4331787@2x.png)

---

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