Fix histogram scale

[MichaelBuessemeyer]

This PR fixes the histogram scale. Previously we downscaled the data before applying the logarithm. This leads to a linear scale.
With this fix, the logarithm is applied before scaling the data to the histogram height.

During testing, I found 2 errors in the console produced by the new downscaling modal added by the multi-resolution PR. I just fixed those on the fly.

URL of deployed dev instance (used for testing):

• https://fixhistogramscale.webknossos.xyz

Steps to test:

• Open a dataset and look at the histogram. Come this with the master. The small values should now be much higher in the histogram. The details in the data should also be increased for small values.
• As I also fiddled with the modal mentioned above please check whether it looks alright and does not throw errors anymore.
• For that: Open a only tracing that did not get downscaled on your local machine and then open the modal using the orange icon above the segmentation layer settings in the tracing view.

Issues:

• fixes Fix histogram scale #4925

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

[MichaelBuessemeyer]

After a discussion, we decided to use a linear scale 📈

[MichaelBuessemeyer]

@daniel-wer I got an exciting update. The scale is now linear and there are now even values on the y-axis 🤯

Could you please check out my changes?

[MichaelBuessemeyer]

A quick internal discussion stated that we do not need the y-axis as the values are sampled and as the scale now is linear (which is what a user should expect)

Nevertheless, could you please check out this PR?

[daniel-wer]

Thanks @MichaelBuessemeyer for fixing this and reacting dynamically to the feedback others and I gave you 🙏

One weird thing I noticed on this branch, but not on master. At first the histogram line is thin, but when moving a histogram handle for the first time, the line becomes thicker all of a sudden and there's also a line at the bottom. See this gif:

[MichaelBuessemeyer]

One weird thing I noticed on this branch, but not on master. At first the histogram line is thin, but when moving a histogram handle for the first time, the line becomes thicker all of a sudden and there's also a line at the bottom.

Oh, thanks for finding this bug. This was caused, because the canvas always used the same path. Refreshing was done in the drawYAxis method. I just added using a new path directly to the beginning of the drawHistogram method to fix this 👍

[daniel-wer]

Nice find with the fix for the double line drawing bug 💯