Persist color channels in rasterize()

[clwgg]

Fixes scverse/spatialdata-plot#249

Please see the above spatialdata-plot issue for a problem description.

This is just a draft of how this issue could be addressed. I could see several different routes this could be tackled, including:

• splitting the tests into a separate function
• using if schema in (Image2DModel, Image3DModel): logic instead of the current try: except:
• using get_channels() instead of xdata.coords["c"].values, although this is a bit awkward since xdata is not the correct type for get_channels(), so one would have to either modify get_channels() or call it on data instead of xdata which feels a little less clean

Let me know what you think!

[giovp]

thanks @clwgg , looks good! would you mind adding a release note here? https://github.com/scverse/spatialdata/blob/main/CHANGELOG.md thanks!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.55%. Comparing base (db6a55b) to head (9d4f98e).
Report is 84 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #544   +/-   ##
=======================================
  Coverage   92.55%   92.55%           
=======================================
  Files          42       42           
  Lines        6000     6001    +1     
=======================================
+ Hits         5553     5554    +1     
  Misses        447      447           

Files	Coverage Δ
src/spatialdata/_core/operations/rasterize.py	83.93% <100.00%> (+0.08%)	⬆️
src/spatialdata/datasets.py	100.00% <100.00%> (ø)

[LucaMarconato]

Thanks @clwgg! I went for "using if schema in (Image2DModel, Image3DModel): logic instead of the current try: except:"; merging now 😊