Histogram followup

[youri-k]

• add sampling for float layers and better support for uint24 layers

URL of deployed dev instance (used for testing):

• https://histogramfollowup.webknossos.xyz

Steps to test:

• request histogram for float layer => response json should contain min, max entries
• request histogram for uint24 layer => response json should contain 3 histograms for each channel

Issues:

• fixes Histogram followup: Refine float/uint16 layer support #4095

---

• Updated changelog
• Updated migration guide if applicable
• Updated documentation if applicable
• Adapted wk-connect if datastore API changes
• Needs datastore update after deployment
• Ready for review

[youri-k]

@daniel-wer could you do the necessary frontend changes? Please note that the json keys slightly changed and that the backend now always sends an array of histograms.

[fm3]

LGTM!

[daniel-wer]

@philippotto Frontend should be ready for review.
I added histogram support for uint16 and float layers, and fixed the uint24 histograms (they are colored now). (The min/max/minRange/maxRange naming is kind of confusing right now, maybe I should rework this code a bit.)

I updated the data_types Dataset to contain a properly scaled uint16 layer now (with values from 0 to 2**16 and not only 2**8) and also another float layer that only contains values between 0 and 1. Please download the updated dataset to properly test this :)

@youri-k Could you also download the updated dataset and have a look at the color_float_small Layer. To me it looks like the min/max range is detected properly, but all the counts are in the first half then (they should be across the whole interval though, I think). Do you agree?

[philippotto]

Awesome! Code looks good 👍 The histogram for the RGB dataset might be a bit too overwhelming, but I think it's fine for this iteration.

Sorry, I had the strong urge to scratch the itch coming from #4129. I pushed a small commit to this PR to resolve this. @MichaelBuessemeyer I hope you didn't do this already somewhere else. I wasn't aware that you were assigned to this. Sorry again!

[MichaelBuessemeyer]

@philippotto It did not work on #4129 yet. Thanks for already solving this issue 🙂.

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