---
title: "preferredAlignmentAndRowBytes(width:height:bitsPerPixel:)"
framework: accelerate
role: symbol
role_heading: Type Method
path: "accelerate/vimage_buffer/preferredalignmentandrowbytes(width:height:bitsperpixel:)"
---

# preferredAlignmentAndRowBytes(width:height:bitsPerPixel:)

Returns the preferred alignment and row bytes for a specified size and bits per pixel.

## Declaration

```swift
static func preferredAlignmentAndRowBytes(width: Int, height: Int, bitsPerPixel: UInt32) throws -> (alignment: Int, rowBytes: Int)
```

## Parameters

- `width`: The width of the image, in pixels.
- `height`: The height of the image, in pixels.
- `bitsPerPixel`: The number of bits in a single pixel.

## Return Value

Return Value A tuple that contains the alignment and row bytes.

## Discussion

Discussion If you provide your own buffer storage, call preferredAlignmentAndRowBytes(width:height:bitsPerPixel:) to get the row stride that ensures your buffer achieves the best performance. let width = 10 let height = 5

let alignmentAndRowBytes = try vImage_Buffer.preferredAlignmentAndRowBytes(     width: width,     height: height,     bitsPerPixel: 8)

// Prints "16". print(alignmentAndRowBytes.rowBytes)

let data = UnsafeMutableRawPointer.allocate(     byteCount: alignmentAndRowBytes.rowBytes * height,     alignment: alignmentAndRowBytes.alignment)

let buffer = vImage_Buffer(data: data,                            height: vImagePixelCount(height),                            width: vImagePixelCount(width),                            rowBytes: alignmentAndRowBytes.rowBytes)

## See Also

### Creating a buffer that references existing data

- [init(data:height:width:rowBytes:)](accelerate/vimage_buffer/init(data:height:width:rowbytes:).md)