Add support for more Image Quality Indexes.

[ashwinn-v]

Is it possible to add more image quality indexes like:

• NormalizedCrossCorrelation
• NormalizedAbsoluteError
• Maximum Difference
  I've been working on python implementations of the same and would like to add them to the current library.

[johnnychen94]

The variants of these are provided in ImageDistances.jl at present

• NormalizedCrossCorrelation. Currently there is ZNCC, see also clarification of NCC and ZNCC ImageDistances.jl#63
• NormalizedAbsoluteError: cityblock(x, y)/mean(abs, y). Because mean(abs, y) loops over y, for better performance, you might want to rewrite the entire calculation in one single loop instead of two loops.
• Maximum Difference: would you mind providing a reference for this? I don't know how this is used in image processing.

We might want to merge ImageDistances and ImageQualityIndexes into one package in the future but that's not of high priority for myself.

[ashwinn-v]

I got to know about Maximum Difference from here:
https://arxiv.org/abs/1604.00546
https://serialsjournals.com/abstract/56305_34-ravichandran.pdf