imfilter!: TypeError: in Type{...} expression, expected UnionAll

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julia> using Images, ImageFiltering

julia> img = zeros(RGB24, (170, 287));

julia> imfilter!(img, img, Kernel.gaussian(8.0))
ERROR: TypeError: in Type{...} expression, expected UnionAll, got Type{RGB24}
Stacktrace:
  [1] filtfft(A::OffsetArrays.OffsetMatrix{RGB24, Matrix{RGB24}}, krn::FFTViews.FFTView{Float64, 2, Matrix{Float64}})
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:845
  [2] _imfilter_fft!(r::ComputationalResources.CPU1{ImageFiltering.Algorithm.FFT}, out::Matrix{RGB24}, A::OffsetArrays.OffsetMatrix{RGB24, Matrix{RGB24}}, kernel::Tuple{OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}, OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}}, border::NoPad{Pad{2}})
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:820
  [3] imfilter!(r::ComputationalResources.CPU1{ImageFiltering.Algorithm.FFT}, out::Matrix{RGB24}, A::OffsetArrays.OffsetMatrix{RGB24, Matrix{RGB24}}, kernel::Tuple{OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}, OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}}, border::NoPad{Pad{2}})
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:807
  [4] imfilter!(r::ComputationalResources.CPU1{ImageFiltering.Algorithm.FFT}, out::Matrix{RGB24}, img::Matrix{RGB24}, kernel::Tuple{OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}, OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}}, border::Pad{2})
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:340
  [5] imfilter!(r::ComputationalResources.CPU1{ImageFiltering.Algorithm.FFT}, out::Matrix{RGB24}, img::Matrix{RGB24}, kernel::Tuple{OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}, OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}}, border::Pad{0})
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:327
  [6] imfilter!(out::Matrix{RGB24}, img::Matrix{RGB24}, kernel::Tuple{OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}, OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}}}, border::Pad{0}, alg::ImageFiltering.Algorithm.FFT)
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:236
  [7] imfilter!
    @ ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:230 [inlined]
  [8] imfilter!
    @ ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:213 [inlined]
  [9] imfilter!(::Matrix{RGB24}, ::Matrix{RGB24}, ::OffsetArrays.OffsetMatrix{Float64, Matrix{Float64}})
    @ ImageFiltering ~/.julia/packages/ImageFiltering/OyzRu/src/imfilter.jl:205
 [10] top-level scope
    @ REPL[3]:1

Hi, thanks for your work. Is the code above supposed to work? I'm not sure if imfilter! with the same source and destination is allowed. It works for kernels with 7.0 or smaller, but for bigger ones it fails.

julia> size(Kernel.gaussian(7.0))  # Doesn't throw.
(29, 29)

julia> size(Kernel.gaussian(7.01)) # Throws.
(33, 33)

Anyway, if the size is the problem perhaps a better error can be reported.
Thanks!

⌃ [6a3955dd] ImageFiltering v0.7.6

Reproduce the RGB24 imfilter! case with Kernel.gaussian(8.0), then inspect src/imfilter.jl around lines 807-845, where the stack trace reports the failure. Compare the behavior with kernels of size 29 and 33 and determine whether aliased source and destination arrays are supported. Done means the case either works correctly or reports a clear, tested error.