# defautl pixel value for out of bounds during registration
**URL:** https://discourse.itk.org/t/defautl-pixel-value-for-out-of-bounds-during-registration/605
**Category:** Beginner Questions
**Created:** [January 19, 2018, 12:30pm UTC](https://discourse.itk.org/t/defautl-pixel-value-for-out-of-bounds-during-registration/605 "2018-01-19T12:30:31Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@asertyuio](https://discourse.itk.org/u/asertyuio)
#### Post date: [January 19, 2018, 12:30pm UTC](https://discourse.itk.org/t/defautl-pixel-value-for-out-of-bounds-during-registration/605/1 "2018-01-19T12:30:32Z")
Dear all,
I’m wondering if there is a way of forcing a default pixel value in the registration metric for out of bounds pixels. I don’t know if I’m clear. Basically I have images for which I know that out of bound value is 0, so how can I make that the metric take that into account…
Thanks for your help!
Yann
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### Author:  [@tim-evain](https://discourse.itk.org/u/tim-evain)
#### Post date: [January 19, 2018, 1:00pm UTC](https://discourse.itk.org/t/defautl-pixel-value-for-out-of-bounds-during-registration/605/2 "2018-01-19T13:00:34Z")
Hi,
As far as I know, metrics don’t use out-of-bound values.
If these values matter for you, one way to do it is to [pad](https://itk.org/Doxygen/html/classitk_1_1PadImageFilter.html) your image with wanted value, thus increasing the extent of considered space.
Note that now that the v4 framework use an intermediate virtual domain to register, I don’t know how the registration behaves if you set a bigger domain than the fixed image one (as I usually set the virtual domain to be the one of the fixed image).
HTH,
Tim
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### Author:  [@asertyuio](https://discourse.itk.org/u/asertyuio)
#### Post date: [January 20, 2018, 4:51pm UTC](https://discourse.itk.org/t/defautl-pixel-value-for-out-of-bounds-during-registration/605/3 "2018-01-20T16:51:45Z")
Ok Thanks Tim, I’ll investigate the padding !