# Error with calculation image difference in Registration QA module using ROI

**URL:** <https://discourse.slicer.org/t/error-with-calculation-image-difference-in-registration-qa-module-using-roi/15293>\
**Category:** Support\
**Created:** [December 30, 2020, 12:48pm UTC](https://discourse.slicer.org/t/error-with-calculation-image-difference-in-registration-qa-module-using-roi/15293 "2020-12-30T12:48:50Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![marianaslicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/marianaslicer/32/8555_2.png) [@marianaslicer](https://discourse.slicer.org/u/marianaslicer)\
**Post date:** [December 30, 2020, 12:48pm UTC](https://discourse.slicer.org/t/error-with-calculation-image-difference-in-registration-qa-module-using-roi/15293/1 "2020-12-30T12:48:50Z")

</div>

Slicer version: 4.13.0 and Slicer 4.11.20200930

Hello everyone,

I want to calculate the image difference between the fixed and warped image, after registration, using a specified ROI. I manually created the ROI, but after assign it the role as ROI in Registration Quality Assurance module, there was a shift and the result of the image difference was wrong.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/c/fc5bb84082f657868b7b5280c476f7edf6ebee2c.jpeg)

The error occurred in both 3D Slicer versions.

Thanks for the help.