rename some Image metrics

[Borda]

What does this PR do?

unify the name convention for image functions
part of #729

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

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[codecov]

Codecov Report

Merging #752 (7dad89f) into master (d044d33) will increase coverage by 21%.
The diff coverage is 87%.

@@           Coverage Diff           @@
##           master   #752     +/-   ##
=======================================
+ Coverage      74%    94%    +21%     
=======================================
  Files         170    170             
  Lines        6831   6858     +27     
=======================================
+ Hits         5027   6472   +1445     
+ Misses       1804    386   -1418     

[ethanwharris]

Looks good, small suggestion 😃

[ethanwharris]

LGTM 😃