Updates for negative axis labels

[K-Meech]

Closes #106

In #106, we'd noted that there were sometimes issues with the axis labels when displaying images with different numbers of dimensions. Looking at the release notes for napari 0.7.0 it seems these issues should have been fixed by their move to using negative axis labels.

To match these new changes, I've updated affected parts of the multi-dimensional images episode including:

• explaining the difference between positive and negative indexes
• updating images that show a slider underneath (so the axis label shown to the left of the slider is now negative)

Even though napari now uses negative indexes thoughout its UI, I thought it was still important to explain positive indexes too (as this is what they will encounter most often using python / numpy etc directly)

[github-actions]

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Rendered Changes

🔍 Inspect the changes: https://github.com/HealthBioscienceIDEAS/microscopy-novice/compare/md-outputs..md-outputs-PR-125

The following changes were observed in the rendered markdown documents:

 fig/brain-napari.png        | Bin 76000 -> 87715 bytes
 fig/cells-napari.png        | Bin 239735 -> 239140 bytes
 fig/cells-time-napari.png   | Bin 192709 -> 194260 bytes
 fig/plate1-czi-napari.png   | Bin 307952 -> 289758 bytes
 md5sum.txt                  |   2 +-
 multi-dimensional-images.md |  55 +++++++++++++++++++++++++++++++++-----------
 6 files changed, 42 insertions(+), 15 deletions(-)

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⏱️ Updated at 2026-06-05 12:47:16 +0000

[stellaprins]

Description looks good to me.

There's still a bunch of screenshots (e.g. episodes\fig\instance-seg-napari.png) that have an index label of 0 instead of what now would be -3.

I would be surprised though if this would confuse anyone? Especially as the emphasis is not so much on the dimensions there.

[K-Meech]

Thanks @stellaprins ! Yes I agree - I only updated the screenshots on episodes where we directly refer to the dimensions / channel axes etc. I figured it wasn't worth updating all the other screenshots for now, as it would take a long time and, as you said, it's unlikely to cause confusion.

[stellaprins]

Sounds sensible to me.

For a future iteration / new material, we could consider adding pictures of the layers rather than screenshots including the napari GUI where appropriate to avoid things getting out of date.