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# equalizeHistogram(binCount:destination:)

Equalizes the histogram of a 32-bit planar pixel buffer.

```
func equalizeHistogram(binCount: Int, destination: vImage.PixelBuffer<vImage.PlanarF>)
```

## Parameters

`binCount`

The number of histogram entries for each channel.

`destination`

The destination pixel buffer.

## Discussion

Use this function to transform an image so that its histogram is more uniformly distributed across the entire range of values.

For example, the following code equalizes the histogram of an image:

```swift
let srcImage =  imageLiteral(resourceName: " ... ").cgImage(
    forProposedRect: nil,
    context: nil,
    hints: nil)!

var cgImageFormat = vImage_CGImageFormat(
    bitsPerComponent: 32,
    bitsPerPixel: 32 * 1,
    colorSpace: CGColorSpaceCreateDeviceGray(),
    bitmapInfo: CGBitmapInfo(rawValue: CGBitmapInfo.byteOrder32Little.rawValue |
                             CGBitmapInfo.floatComponents.rawValue |
                             CGImageAlphaInfo.none.rawValue))!

let buffer = try vImage.PixelBuffer(
    cgImage: srcImage,
    cgImageFormat: &cgImageFormat,
    pixelFormat: vImage.PlanarF.self)

buffer.equalizeHistogram(binCount: 1024,
                         destination: buffer)

let outputImage = buffer.makeCGImage(cgImageFormat: cgImageFormat)
```

## See Also

  <doc://com.apple.accelerate/documentation/Accelerate/enhancing-image-contrast-with-histogram-manipulation>


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