# Transform Hounsfield unit to intensity values
**URL:** https://discourse.itk.org/t/transform-hounsfield-unit-to-intensity-values/2818
**Category:** Beginner Questions
**Created:** [March 11, 2020, 12:38pm UTC](https://discourse.itk.org/t/transform-hounsfield-unit-to-intensity-values/2818 "2020-03-11T12:38:13Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@flaviu2](https://discourse.itk.org/u/flaviu2)
#### Post date: [March 11, 2020, 12:38pm UTC](https://discourse.itk.org/t/transform-hounsfield-unit-to-intensity-values/2818/1 "2020-03-11T12:38:14Z")
Hello all of you. can you tell me how to convert Hounsfield unit to intensity window level values ? I far I understand, there is standard mathematical way called windowing …
But how can apply it when I have, let say bone HU (1000 - 1900) and I want to know the window level values associated with 1000 HU ? Can you give a help hand ?
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### Author:  [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [March 11, 2020, 2:10pm UTC](https://discourse.itk.org/t/transform-hounsfield-unit-to-intensity-values/2818/2 "2020-03-11T14:10:44Z")
Windowing transforms intensities from one range to another, for example from 1000-1900 into 0-255 in order to display CT pixels on regular screens. Values outside the range map to endpoints: -1000, 0, 200 and 999 all map to 0, while 1901, 3000 and 25000 all map to 255. Window is the width of the range (901 in the example above) and level is center of the range (1450.5 in the example).
Therefore, window and level need a range to exist, they are not defined for a single value.
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### Author:  [@flaviu2](https://discourse.itk.org/u/flaviu2)
#### Post date: [March 11, 2020, 2:23pm UTC](https://discourse.itk.org/t/transform-hounsfield-unit-to-intensity-values/2818/3 "2020-03-11T14:23:20Z")
Thank you Dzenan, I got it !