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# kCVPixelFormatBlockWidth

```
let kCVPixelFormatBlockWidth: CFString
```

## Discussion

The width, in pixels, of the smallest byte-addressable group of pixels (type `CFNumber`). Used to assist with allocating memory for pixel formats that don’t have an integer value for bytes per pixel. Assumed to be 1 if this key is not present. Here are some examples of block widths for standard pixel formats:

- 8-bit luminance only, block width is 1, the bits per block value is 8.
- 16-bit 1555 RGB, block width is 1, the bits per block value is 16.
- 32-bit 8888 ARGB, block width is 1, the bits per block value is 32.
- 2vuy (CbYCrY), block width is 2, the bits per block value is 32.
- 1-bit bitmap, block width is 8, the bits per block value is 8.
- v210, block width is 6, the bits per block value is 128 .

---

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