Adds deprecation warnings and exports ImageContrastAdjustment

[zygmuntszpak]

Also removes code in exposure.jl which is now found in the ImageContrastAdjustment.jl package.

[zygmuntszpak]

Addresses part of #841

[zygmuntszpak]

Are we OK to bump the minimum requirement for Julia for the Images package to version 1.1? The minimum requirement for ImageContrastAdjustment is Julia 1.1 and I now recall that this is because I used Base.@kwdef in various place. That function only got introduced in Julia version 1.1 https://pkg.julialang.org/docs/julia/THl1k/1.1.1/NEWS.html

[Tokazama]

I personally think that if JuliaPro has reached a version number for a while it's probably safe to set it as the minimum version number. They seem to be pretty proactive about making sure packages work with each new JuliaPro release.

[johnnychen94]

Unless there's another LTS version, dropping 1.0 compatibility is really risking

[Tokazama]

I guess we should probably consider which "Risk Tolerance Persona" we should cater to.

[timholy]

Yeah, I'm a bit uncomfortable about not continuing to support Julia 1.0. How bad would it be to just write out the default-filling constructors manually?

Otherwise, this is really nice to see!

[zygmuntszpak]

I've tagged a new version of ImageContrastAdjustment which now supports Julia 1.0. Hence, I am going to close and re-open this pull-request to trigger a new build.

[zygmuntszpak]

@timholy I'll wait for you to approve this before I merge.

[timholy]

Main issue is I think your depwarns don't actually work. If you tested them and I'm wrong about that, please let me know.

[timholy]

Looking good! Just a couple of changes below.

Eventually, we'll just delete test/exposure.jl, right? If yes, maybe add a comment at the top of the file saying it can be removed when src/deprecations.jl is deleted. If no, we might want to separate out the stuff we'll keep and move the stuff we'll delete into test/deprecations.jl.

[zygmuntszpak]

• Moved all deprecated code from exposure.jl into deprecations.jl
• Deprecation messages say "is deprecated" instead of "will be deprecated".
• Removed mention of adjust_histogram, adjust_histogram!, Matching, Equalization and build_histogram from export statement (it is now automatically reexported)
• Rerouted old variants of adjust_histogram, adjust_histogram!, and build_histogram so that they call the new API in ImageContrastAdjustment. User receives a deprecation message, but their code still works (with the exception of code that used Matching()).
• Any code that matched histograms using adjust_histogram(Matching(), ...) is broken. The user receives an error message stating that the keyword targetimg in the construction of Matching needs to be supplied.

[johnnychen94]

It's the Spring festival here in China so I didn't follow the whole discussion here with my limited time. Looks like there're still some breaking changes, so a minor version bump is required, i.e., 0.21.0

[timholy]

Let's give anyone else who wants to review another day to check it, and then merge.

[timholy]

Thanks for merging, I've been swamped! We should get this out as 0.21, will try to get to it over the weekend.

[timholy]

And it's out! Thanks again @zygmuntszpak, great contribution!

[tlnagy]

The suggested fix in the dep warning for imadjustintensity doesn't work:

julia> using Images

julia> img = Gray{N0f8}.(rand(10, 10));

julia> imadjustintensity(img);
┌ Warning: `imadjustintensity` will be removed in a future release, please use `adjust_histogram(img, LinearStretching())` instead.
│   caller = top-level scope at REPL[10]:1
└ @ Core REPL[10]:1

julia> adjust_histogram(img, LinearStretching())
ERROR: MethodError: no method matching adjust_histogram(::Array{Gray{Normed{UInt8,8}},2}, ::LinearStretching{Float64,Float64})
Stacktrace:
 [1] top-level scope at REPL[11]:1

[zygmuntszpak]

It looks like the reason for this is that I forgot to add

import ImageContrastAdjustment: adjust_histogram, adjust_histogram!

to ensure that the new definitions of adjust_histogram and adjust_histogram! in deprecations.jl don't make the definitions in ImageContrastAdjustment "disappear".

I'm putting together a quick fix, and will add some test to make sure that the advertised API is actually callable. Sorry for the oversight, and thanks for reporting the issue.

[timholy]

Another thing we should have done is fill in the parameters for the actual usage; anyone who copy/pastes the suggested deprecation would be throwing away whatever custom parameters they're supplying for the call. A prototype of a better deprecation might have been

@deprecate clahe(img, nbins=100) adjust_histogram(img, AdaptiveEqualization(; nbins))

and then the user will see a copy/pastable suggestion.