---
title: areaMinimumAlpha()
framework: coreimage
role: symbol
role_heading: Type Method
path: coreimage/cifilter-swift.class/areaminimumalpha()
---

# areaMinimumAlpha()

Calculates the pixel within a specified area that has the smallest alpha value.

## Declaration

```swift
class func areaMinimumAlpha() -> any CIFilter & CIAreaMinimumAlpha
```

## Return Value

Return Value A 1 x 1 pixel image containing the color with the smallest alpha value.

## Discussion

Discussion This method applies the area minimum alpha filter to an image. This effect finds and returns the pixel with the lowest alpha value in the region defined by extent. The area minimum alpha filter uses the following properties: The following code creates a filter that results in a 1 x 1 pixel image containing the color with the lowest alpha value: func areaMinimumAlpha(inputImage: CIImage) -> CIImage {     let filter = CIFilter.areaMinimumAlpha()     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! }

## See Also

### Filters

- [areaAverage()](coreimage/cifilter-swift.class/areaaverage().md)
- [areaHistogram()](coreimage/cifilter-swift.class/areahistogram().md)
- [areaLogarithmicHistogram()](coreimage/cifilter-swift.class/arealogarithmichistogram().md)
- [areaMaximum()](coreimage/cifilter-swift.class/areamaximum().md)
- [areaMaximumAlpha()](coreimage/cifilter-swift.class/areamaximumalpha().md)
- [areaMinimum()](coreimage/cifilter-swift.class/areaminimum().md)
- [areaMinMax()](coreimage/cifilter-swift.class/areaminmax().md)
- [areaMinMaxRed()](coreimage/cifilter-swift.class/areaminmaxred().md)
- [columnAverage()](coreimage/cifilter-swift.class/columnaverage().md)
- [histogramDisplay()](coreimage/cifilter-swift.class/histogramdisplay().md)
- [kMeans()](coreimage/cifilter-swift.class/kmeans().md)
- [rowAverage()](coreimage/cifilter-swift.class/rowaverage().md)