# Is there no binary type '01' in the pixel type of SimpleItk?
**URL:** https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211
**Category:** Algorithms
**Tags:** python, simpleitk
**Created:** [September 15, 2023, 12:50pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211 "2023-09-15T12:50:01Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@jumbojing](https://discourse.itk.org/u/jumbojing)
#### Post date: [September 15, 2023, 12:50pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/1 "2023-09-15T12:50:01Z")
## Is there no binary type ‘01’ in the pixel type of SimpleItk?
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### Author:  [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [September 15, 2023, 1:00pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/2 "2023-09-15T13:00:05Z")
SimpleITK and ITK commonly use unsigned bytes, uint8 or `sitkUInt8` type to represent binary images. These are commonly referred to as mask images. We have a FAQ entry in SimpleITK which discussed this common convention:
[https://simpleitk.readthedocs.io/en/master/conventions.html#mask-image-types-and-default-values](https://simpleitk.readthedocs.io/en/master/conventions.html#mask-image-types-and-default-values)
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### Author:  [@jumbojing](https://discourse.itk.org/u/jumbojing)
#### Post date: [September 15, 2023, 2:43pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/3 "2023-09-15T14:43:13Z")
Why is there no ‘2-bit int’ type? I think this type is very commonly used…
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### Author:  [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [September 15, 2023, 2:54pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/4 "2023-09-15T14:54:21Z")
It is not directly addressable in memory. Reading memory which is not aligned with processor cache lines is inconvenient/slower, and most processor architectures, and therefore most programming languages, do not expose `bit` as a primitive type, like they do for `int`.
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### Author:  [@jumbojing](https://discourse.itk.org/u/jumbojing)
#### Post date: [September 15, 2023, 3:17pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/5 "2023-09-15T15:17:11Z")
Can’t make a _pseudo_ `bit int` type?
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### Author:  [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [September 15, 2023, 3:25pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/6 "2023-09-15T15:25:00Z")
In C and C++, that is available in structs. Read more about it:
>
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### Author:  [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [September 15, 2023, 3:26pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/7 "2023-09-15T15:26:26Z")
Also, C++ has a specialized [`std::vector`](https://stackoverflow.com/questions/17794569/why-isnt-vectorbool-a-stl-container).
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### Author:  [@jumbojing](https://discourse.itk.org/u/jumbojing)
#### Post date: [September 15, 2023, 3:32pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/8 "2023-09-15T15:32:42Z")
Howto write a `bit-int` type with python?
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### Author:  [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [September 15, 2023, 3:43pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/9 "2023-09-15T15:43:12Z")
I don’t think Python has that:
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### Author:  [@jumbojing](https://discourse.itk.org/u/jumbojing)
#### Post date: [September 15, 2023, 10:47pm UTC](https://discourse.itk.org/t/is-there-no-binary-type-01-in-the-pixel-type-of-simpleitk/6211/10 "2023-09-15T22:47:51Z")
Thanks!..it’s a hassle.