WIP: add macro channelwise

[johnnychen94]

This is the very draft of my @channelwise idea in JuliaImages/Images.jl#817

The basic idea is to insert a channelview to each possible argument. For example, @channelwise euclidean(x, y) is equivalent to euclidean(channelview(x), channelview(y)).

I'm not familiar with the macro mechanism at present, the current code doesn't work properly. (I guess I need to quote the codes in has_channel for Symbol and Expr)

[timholy]

Out of curiosity, how often do you need the view? Could we do something similar using mapc or mapreducec? The reason I ask is that it's more straightforward to achieve very high performance that way (tuples are almost always better than arrays for performance).

[AliMalik9599]

Hey @johnnychen94 so I think I figured out how to make this work. The only problem is that channelview returns a Base.reinterpretArray, so I do not know how to send this to euclidean (just as an example) without specifying the parameters for that function as Base.reinterpretarray{...}. Any advice? Thanks!

[johnnychen94]

Hmmm, could you illustrate it a bit more? I probably don't get what your problem is. The functions(e.g., euclidean) should just work generically for AbstractArray.

[AliMalik9599]

Yes, I think I made a mistake as I was testing using a custom function I made which did not have the correct code to work for any abstract array. I think this works now, in what file can I find the euclidean function? Thanks for the help

[johnnychen94]

euclidean is defined in ImageDistances (for images) and Distances (for numerical array)