Relax Colorant type

src/preprocessing.jl

@@ -165,20 +165,20 @@ function apply!(buf, ::ImageToTensor, image::Image; randstate = nothing)
     return buf
 end
 
-function imagetotensor(image::AbstractArray{C, N}, T = Float32) where {C<:Color, N}
+function imagetotensor(image::AbstractArray{C, N}, T = Float32) where {C<:Colorant, N}
     T.(PermutedDimsArray(_channelview(image), ((i for i in 2:N+1)..., 1)))
 end
 
 #=
-function imagetotensor(image::AbstractArray{C, N}, T = Float32) where {TC, C<:Color{TC, 1}, N}
+function imagetotensor(image::AbstractArray{C, N}, T = Float32) where {TC, C<:Colorant{TC, 1}, N}
     return T.(_channelview(image))
 end
 =#
 
 
 # TODO: relax color type constraint, implement for other colors
 # single-channel colors need a `channelview` that also expands the array
-function imagetotensor!(buf, image::AbstractArray{<:Color, N}) where N
+function imagetotensor!(buf, image::AbstractArray{<:Colorant, N}) where N
     permutedims!(
         buf,
         _channelview(image),
@@ -197,22 +197,19 @@ function tensortoimage(a::AbstractArray)
     end
 end
 
-function tensortoimage(C::Type{<:Color}, a::AbstractArray{T, N}) where {T, N}
+function tensortoimage(C::Type{<:Colorant}, a::AbstractArray{T, N}) where {T, N}
     perm = (N, 1:N-1...)
     return _colorview(C, PermutedDimsArray(a, perm))
 end
 
-
-function _channelview(img)
-    chview = channelview(img)
-    # for single-channel colors, expand the color dimension anyway
-    if size(img) == size(chview)
-        chview = reshape(chview, 1, size(chview)...)
-    end
-    return chview
+# for single-channel colors, expand the color dimension anyway
+_channelview(img::AbstractArray{<:Colorant{T, N}}) where {T, N} = channelview(img)
+function _channelview(img::AbstractArray{<:Colorant{T, 1}}) where T
+    cv = channelview(img)
+    return reshape(cv, 1, size(cv)...)
 end
 
-function _colorview(C::Type{<:Color}, img)
+function _colorview(C::Type{<:Colorant}, img)
     if size(img, 1) == 1
         img = reshape(img, size(img)[2:end])
     end