# A problem about  window\_leveling mapping issues

**URL:** <https://discourse.slicer.org/t/a-problem-about-window-leveling-mapping-issues/33419>\
**Category:** Support\
**Created:** [December 17, 2023, 1:12pm UTC](https://discourse.slicer.org/t/a-problem-about-window-leveling-mapping-issues/33419 "2023-12-17T13:12:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![l\_xx](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/l_xx/32/68699_2.png) [@l\_xx](https://discourse.slicer.org/u/l_xx)\
**Post date:** [December 17, 2023, 1:12pm UTC](https://discourse.slicer.org/t/a-problem-about-window-leveling-mapping-issues/33419/1 "2023-12-17T13:12:34Z")

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Is there any way to implement the mapping of my red arrows, and the CT displayed will still be normal? The top one was linearly mapped, but only the window level of the bone was left. What I need is the bottom result, that is Normal results.

 ![c94597384e409dc609cc624bf85dcba](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/e/ee34ea3d4ab92d79dfa9c485ed89b967112198d2.jpeg)

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [March 17, 2024, 12:01pm UTC](https://discourse.slicer.org/t/a-problem-about-window-leveling-mapping-issues/33419/2 "2024-03-17T12:01:27Z")

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Window/level mapping from HU to displayed range (black to white) is always done using a linear ramp function. Both CT display that you show above are normal. It is up to you what you want to emphasize (bone, soft-tissues, etc.).

In addition to the window/level mapping, there is an optional thresholding operation (off by default), that allows hiding part of the image that is outside the specified range.