---
title: "extractChannel(at:destination:)"
framework: accelerate
role: symbol
role_heading: Instance Method
path: "accelerate/vimage/pixelbuffer/extractchannel(at:destination:)-8xrq1"
---

# extractChannel(at:destination:)

Extracts a single channel from an 32-bit-per-channel, 4-channel interleaved pixel buffer.

## Declaration

```swift
func extractChannel(at channelIndex: Int, destination: vImage.PixelBuffer<vImage.PlanarF>)
```

## Parameters

- `channelIndex`: The index of the channel that the function extracts.
- `destination`: The destination pixel buffer.

## Discussion

Discussion For example, the following code extracts channel `2` from a four-channel pixel buffer. let src = vImage.PixelBuffer<vImage.InterleavedFx4>(     pixelValues: [0.10, 0.11, 0.12, 0.13,                   0.20, 0.21, 0.22, 0.23,                   0.30, 0.31, 0.32, 0.33],     size: vImage.Size(width: 1, height: 3))

let dest = vImage.PixelBuffer<vImage.PlanarF>(     size: src.size)

src.extractChannel(at: 2,                    destination: dest)

// Prints "[0.12, 0.22, 0.32]" print(dest.array)

## See Also

### Extracting Channels

- [extractChannel(at:destination:)](accelerate/vimage/pixelbuffer/extractchannel(at:destination:)-ageg.md)
- [extractChannel(at:destination:)](accelerate/vimage/pixelbuffer/extractchannel(at:destination:)-i1zm.md)