Missed img vol return tutorial updates

[garrettwrong]

Somehow these were missed.

We will be adding doc building to the CI jobs that run on "Review" readiness, since I forgot these (my bad).

[codecov]

Codecov Report

Merging #884 (ff274fa) into develop (1ae3546) will decrease coverage by 0.07%.
The diff coverage is 94.73%.

@@             Coverage Diff             @@
##           develop     #884      +/-   ##
===========================================
- Coverage    88.70%   88.63%   -0.07%     
===========================================
  Files          117      117              
  Lines         9788     9575     -213     
===========================================
- Hits          8682     8487     -195     
+ Misses        1106     1088      -18     

Impacted Files	Coverage Δ
src/aspire/source/image.py	91.62% <94.44%> (-0.31%)	⬇️
src/aspire/source/__init__.py	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

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[garrettwrong]

Moving to merge this so develop docs will build.

Discussed converting the older scripts towards using the gallery formatting so we can just avoid the ugly subplot usage. (Will make an issue).

[j-c-c]

This looks good. Aside from the one vol plot in experimental I couldn't find any other instances.

[janden]

Looks good.

There's an interesting point here, though: we have to call copy on the ndarrays returned by asnumpy to avoid modifying the original Image? We may want to consider forcing asnumpy to make a copy (or to mark it read-only) to avoid this issue. This may be less important to Images, but when they're part of a source, we certainly don't want people to go around modifying them by accident (especially if the sources are to be seen as immutable).

[garrettwrong]

I agree that is a concern. Disabling writable is probably the best compromise to avoid unneeded deep copies. I'll put that together. Thanks!

https://numpy.org/doc/stable/reference/generated/numpy.ndarray.flags.html