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# vImageOverwriteChannelsWithScalar_ARGBFFFF(_:_:_:_:_:)

Overwrites the selected channels of a 32-bit-per-channel, 4-channel interleaved buffer with the specified scalar value.

```
func vImageOverwriteChannelsWithScalar_ARGBFFFF(_ scalar: Pixel_F, _ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ copyMask: UInt8, _ flags: vImage_Flags) -> vImage_Error
```

## Parameters

`scalar`

The scalar value that provides the new channel values.

`src`

The source vImage buffer that provides the original pixel values.

`dest`

A pointer to the destination vImage buffer structure. You’re responsible for filling out the [`height`](/documentation/Accelerate/vImage_Buffer/height), [`width`](/documentation/Accelerate/vImage_Buffer/width), and [`rowBytes`](/documentation/Accelerate/vImage_Buffer/rowBytes) fields of this structure, and for allocating a data buffer of the appropriate size. On return, the data buffer this structure points to contains the destination image data. When you no longer need the data buffer, deallocate the memory to prevent memory leaks.

`copyMask`

A bitmask that specifies the channel or channels that the function overwrites with the scalar value. The value `0x8` represents channel `0`, the value `0x4` represents channel `1`, the value `0x2` represents channel `2`, and the value `0x1` represents channel `3`.

`flags`

The options to use when performing the operation. If your code implements its own tiling or its own multithreading, pass [`kvImageDoNotTile`](/documentation/Accelerate/kvImageDoNotTile); otherwise, pass [`kvImageNoFlags`](/documentation/Accelerate/kvImageNoFlags).

## Return Value

[`kvImageNoError`](/documentation/Accelerate/kvImageNoError); otherwise, one of the error codes in <doc://com.apple.documentation/documentation/Accelerate/data-types-and-constants>.

## Discussion

The following code overwrites channel `0` of the source pixels in `pixelBuffer` with the scalar value:

```swift
let pixelBuffer = vImage.PixelBuffer<vImage.InterleavedFx4>(
    pixelValues: [10, 20, 30, 40,
                  50, 60, 70, 80],
    size: .init(width: 1, height: 2))

let scalar: Pixel_F = 101

pixelBuffer.withUnsafePointerToVImageBuffer { buf in
    _ = vImageOverwriteChannelsWithScalar_ARGBFFFF(scalar,
                                                   buf,
                                                   buf,
                                                   0x8,
                                                   vImage_Flags(kvImageNoFlags))
}

// Prints:
//      "[101.0, 20.0, 30.0, 40.0,
//        101.0, 60.0, 70.0, 80.0]"
print(pixelBuffer.array)
```

---

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