Added rgb_to_grayscale

[IMvision12]

@fchollet

[IMvision12]

Hi @fchollet Thanks for the initial review, can you tell me how can i fix failing tests?

[fchollet]

There seems to be more than one issue with the unit tests. For the particular issue you mentioned, I think you just need to make sure to call super().__init__(). Basically just do the same as what the other ops are doing and it will work.

[IMvision12]

@fchollet can you review?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 74.71264% with 22 lines in your changes are missing coverage. Please review.

Project coverage is 76.24%. Comparing base (cbb64ab) to head (98e587d).
Report is 86 commits behind head on master.

Files	Patch %	Lines
keras/ops/image.py	63.63%	4 Missing and 4 partials ⚠️
keras/backend/torch/image.py	73.68%	3 Missing and 2 partials ⚠️
keras/backend/jax/image.py	81.25%	1 Missing and 2 partials ⚠️
keras/backend/numpy/image.py	81.25%	1 Missing and 2 partials ⚠️
keras/backend/tensorflow/image.py	78.57%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #19393      +/-   ##
==========================================
+ Coverage   75.95%   76.24%   +0.28%     
==========================================
  Files         366      367       +1     
  Lines       40707    41161     +454     
  Branches     7934     8051     +117     
==========================================
+ Hits        30920    31384     +464     
+ Misses       8074     8057      -17     
- Partials     1713     1720       +7     

Flag	Coverage Δ
keras	76.10% <74.71%> (+0.29%)	⬆️
keras-jax	60.24% <33.33%> (+0.14%)	⬆️
keras-numpy	54.17% <34.48%> (+0.12%)	⬆️
keras-tensorflow	61.51% <31.03%> (+0.11%)	⬆️
keras-torch	60.31% <34.48%> (+0.03%)	⬆️

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[fchollet]

Thanks for the update -- the code looks good overall, however the tests are still failing for two backends with shape correctness issues. Please take a look.

[fchollet]

LGTM, thank you!