Add no-op image_ready enhancement

[mraspaud]

This PR adds a no-op enhancement for data that is image-ready, ie where nothing needs to be done. The enhancement key (standard_name) is called image_ready.

I didn't add any test, as the function is not doing anything. But shout if you think I should do otherwise.

[pnuu]

I'm curious to see if there's a performance boost to what I've had before. I've only added a crude stretch from 0 to 1 for the composites using DayNightCompositor as enhancement. Will test tomorrow.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.08%. Comparing base (ba30733) to head (b408e65).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2933   +/-   ##
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  Coverage   96.08%   96.08%           
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  Files         375      375           
  Lines       54578    54586    +8     
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+ Hits        52441    52449    +8     
  Misses       2137     2137           

Flag	Coverage Δ
behaviourtests	3.98% <11.11%> (+<0.01%)	⬆️
unittests	96.18% <100.00%> (+<0.01%)	⬆️

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[mraspaud]

I'm curious to see if there's a performance boost to what I've had before. I've only added a crude stretch from 0 to 1 for the composites using DayNightCompositor as enhancement. Will test tomorrow.

IIRC, the stretch function is "smart" and doesn't do anything if min and max are respectively 0 and 1. But the method in this PR is cleaner I think.

[coveralls]

Pull Request Test Coverage Report for Build 11379521585

Details

• 9 of 9 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.001%) to 96.181%

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Totals
Change from base Build 11365975625:	0.001%
Covered Lines:	52685
Relevant Lines:	54777

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💛 - Coveralls

[pnuu]

I'm curious to see if there's a performance boost to what I've had before. I've only added a crude stretch from 0 to 1 for the composites using DayNightCompositor as enhancement. Will test tomorrow.

IIRC, the stretch function is "smart" and doesn't do anything if min and max are respectively 0 and 1. But the method in this PR is cleaner I think.

You were right, no difference in performance.

[pnuu]

LGTM

[ameraner]

What is the difference between using this and a simple operations: []?

[mraspaud]

IIRC, if operations is empty, a default enhancement is applied. This block any enhancement.

[gerritholl]

As far as I remember, operations: [] means no enhancement is applied. If operations is not defined at all, the default enhancement is applied. It is possible that I am mistaken.

[mraspaud]

Ok, I can check, but either way, isn't it better to have it explicit?

[ameraner]

Exactly, as Gerrit is saying, operations: [] means no enhancement, I use it explicitly when I don't want the default enhancement to kick in, e.g. for a BackgroundCompositor (see for example these usages). This is actually the indicated way in the documentation, see the warning box here: https://satpy.readthedocs.io/en/stable/composites.html#enhancing-the-images

[gerritholl]

Ok, I can check, but either way, isn't it better to have it explicit?

Probably yes, but then please also update the documentation in the warning box that Andrea linked :)

[mraspaud]

Will do!