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# blockSize

Used to assist with allocating memory for pixel formats that don’t have an integer value for bytes per pixel.
Block width/height is essentially the width/height in pixels of the smallest “byte addressable” group of pixels.
This works in close conjunction with [`bitsPerBlock`](/documentation/CoreVideo/CVPixelFormatDescription/PixelLayout/bitsPerBlock).
Examples:
8-bit luminance only, blockSize.width would be 1, bitsPerBlock would be 8
16-bit 1555 RGB, blockSize.width would be 1, bitsPerBlock would be 16
32-bit 8888 ARGB, blockSize.width would be 1, bitsPerBlock would be 32
2vuy (CbYCrY), blockSize.width would be 2, bitsPerBlock would be 32
1-bit bitmap, blockSize.width would be 8, bitsPerBlock would be 8
v210, blockSize.width would be 6, bitsPerBlock would be 128

```
var blockSize: CVImageSize
```

---

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