# MicroCT--Rescale, Resample

**URL:** <https://discourse.slicer.org/t/microct-rescale-resample/14388>\
**Category:** Support\
**Created:** [November 2, 2020, 4:38pm UTC](https://discourse.slicer.org/t/microct-rescale-resample/14388 "2020-11-02T16:38:57Z")\
**Posts on this page:** 1\
**Showing post:** 3

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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:** [November 2, 2020, 5:10pm UTC](https://discourse.slicer.org/t/microct-rescale-resample/14388/3 "2020-11-02T17:10:48Z")

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> [@tsehrhardt](#):
>
> shows up as a 700mb file in my file explorer, but when I open it in Fiji, it shows it as 2.1gb.

File size may be smaller due to image compression, but since it is exactly 3x more, it is also possible that Fiji chooses to store the image in 3 channels (RGB). You can try to change color mode to grayscale.

> [@tsehrhardt](#):
>
> When I re-import the DICOM slices into Slicer 4.11 and re-save the volume and rescale, I’m getting the 8bit to show in my file explorer as 2.1gb

Check Volume module / Volume information / Number of scalars. If you see 3 there then it confirms that Fiji converted the grayscale image to RGB, needlessly tripling the memory usage.

> [@tsehrhardt](#):
>
> Since I don’t need to generate a 3D model from an 82 micron scan, I resampled to 0.1637 mm using Resample Scalar Volume. The new volume shows the correct dimensions (still showing as microns though in Fiji), but shows the Scalar Range as 0 to 254 instead of 0 to 255. This happens in both Slicer 4.10.2 and 4.11.

When you resample your image to lower resolution then small details in the image are lost. For example, if you only had a few, isolated voxels that had the intensity value of 255 then it is very likely that you will not have a value of 255 in the downsampled output. You can slightly increase the quality by applying antialiasing filter (low-pass filter, such as Gaussian smoothing should suffice), but it rarely makes a practical difference (see [this discussion](https://discourse.slicer.org/t/downsampling-nrrds/14033/10) for details).

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