Posted by
Fred Damen on
URL: http://imagej.273.s1.nabble.com/Hyperstack-with-nz-1-problem-tp5019980p5020061.html
Greetings,
Beauty is in the eyes of the beholder... and my beauty is MRI.
In MRI a slice is a 3D entity with length, width and depth -- which we call
slice thickness. A voxel, i.e., volume element, represents a single value for
a location in 3D space. Voxels are contiguous within the slice and depending
on how data was collected may be contiguous in z also -- you can have what we
call an interslice gap. In MRI there is no way to acquire a slice with
infinitesimally thin slice thickness. Usually the slice thickness is more
than twice that of the in-slice voxel size.
Thanks for the info,
Fred
On Fri, February 9, 2018 11:03 am, Herbie wrote:
> Good day!
>
> "[...] so that ImageJ treats a single slice as a volume?"
>
> A slice is an image!
>
> A slice has no extension orthogonal to itself.
> A pixel also has no extension in any direction because it is a mathematical
> point in 2D, i.e. a number or sample value.
> A voxel also has no extension in any direction because it is a mathematical
> point in 3D, i.e. a number or sample value.
>
> Pixels, i.e. values at points in 2D, are arranged in a 2D grid and the
> sometimes equidistant *spacing* of the grid points is often confused with
> the pixel size, that actually doesn't exist.
> (A pixel doesn't have a size.)
>
> Voxels, i.e. values at points in 3D, are arranged in a 3D grid and the
> sometimes equidistant *spacing* of the grid points is often confused with
> the voxel size, that actually doesn't exist.
> (A voxel doesn't have a size.)
>
> In short:
> A slice has no neighbors orthogonal to itself, i.e. there is no (defined)
> spacing in the third dimension.
>
> That said, you may indeed use dummy slices to define the missing spacing!
>
> HTH
>
> Herbie
>
>
>
> --
> Sent from:
http://imagej.1557.x6.nabble.com/>
> --
> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>
--
ImageJ mailing list:
http://imagej.nih.gov/ij/list.html