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Refactor imresize using Interpolations #7

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Feb 23, 2017
Merged

Refactor imresize using Interpolations #7

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d96ed6c
Refactor imresize and cleanup tests
Evizero Feb 17, 2017
634a2c3
add method for imresize with AbstractInterpolation
Evizero Feb 18, 2017
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2 changes: 1 addition & 1 deletion REQUIRE
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
julia 0.5
ImageCore 0.1.2
CoordinateTransformations
CoordinateTransformations 0.4.0
Interpolations 0.3.7
OffsetArrays
StaticArrays
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1 change: 1 addition & 0 deletions src/ImageTransformations.jl
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@@ -1,3 +1,4 @@
__precompile__()
module ImageTransformations

using CoordinateTransformations, Interpolations, OffsetArrays, StaticArrays, Colors, ColorVectorSpace, ImageCore
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55 changes: 28 additions & 27 deletions src/resizing.jl
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Expand Up @@ -18,7 +18,10 @@ function restrict{T,N}(A::AbstractArray{T,N}, dim::Integer)
return A
end
newsz = ntuple(i->i==dim?restrict_size(size(A,dim)):size(A,i), Val{N})
out = Array{typeof(A[1]/4+A[2]/2),N}(newsz)
# FIXME: The following line fails for interpolations because
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Interesting. I haven't coded with Interpolations recently, but if it supports what we need then

R = CartesianRange(indices(A))
f = A[first(R)]

should work. Though perhaps the better strategy would to add support for first to Interpolations.

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first(A) works for interpolations. A[1] does not. For extrapolations neither work

# interpolations can be accessed linearily A[i].
# out = Array{typeof(A[1]/4+A[2]/2),N}(newsz)
out = Array{typeof(first(A)/4+first(A)/2),N}(newsz)
restrict!(out, A, dim)
out
end
Expand Down Expand Up @@ -78,7 +81,7 @@ for N = 1:5
oneeighth = convert(eltype(T), 0.125)
indx = 0
if dim == 1
z = convert(T, zero(A[1]))
z = convert(T, zero(first(A)))
@inbounds @nloops $N i d->(d==1 ? (1:1) : (1:size(A,d))) d->(j_d = i_d) begin
c = d = z
for k = 1:size(out,1)-1
Expand Down Expand Up @@ -125,32 +128,30 @@ end

restrict_size(len::Integer) = isodd(len) ? (len+1)>>1 : (len>>1)+1

## imresize
function imresize!(resized, original::AbstractMatrix)
scale1 = (size(original,1)-1)/(size(resized,1)-0.999f0)
scale2 = (size(original,2)-1)/(size(resized,2)-0.999f0)
for jr = 0:size(resized,2)-1
jo = scale2*jr
ijo = trunc(Int, jo)
fjo = jo - oftype(jo, ijo)
@inbounds for ir = 0:size(resized,1)-1
io = scale1*ir
iio = trunc(Int, io)
fio = io - oftype(io, iio)
tmp = (1-fio)*((1-fjo)*original[iio+1,ijo+1] +
fjo*original[iio+1,ijo+2]) +
+ fio*((1-fjo)*original[iio+2,ijo+1] +
fjo*original[iio+2,ijo+2])
resized[ir+1,jr+1] = convertsafely(eltype(resized), tmp)
end
end
resized
# imresize
imresize(original::AbstractArray, dim1, dimN...) = imresize(original, (dim1,dimN...))

function imresize{T,N}(original::AbstractArray{T,N}, short_size::NTuple)
len_short = length(short_size)
new_size = ntuple(i -> (i > len_short ? size(original,i) : short_size[i]), N)
imresize(original, new_size)
end

imresize(original, new_size) = size(original) == new_size ? copy!(similar(original), original) : imresize!(similar(original, new_size), original)
function imresize{T,N}(original::AbstractArray{T,N}, new_size::NTuple{N})
if size(original) == new_size
copy!(similar(original), original)
else
imresize!(similar(original, new_size), original)
end
end

convertsafely{T<:AbstractFloat}(::Type{T}, val) = convert(T, val)
convertsafely{T<:Integer}(::Type{T}, val::Integer) = convert(T, val)
convertsafely{T<:Integer}(::Type{T}, val::AbstractFloat) = round(T, val)
convertsafely{T}(::Type{T}, val) = convert(T, val)
function imresize!{T,S,N}(resized::AbstractArray{T,N}, original::AbstractArray{S,N})
itp = interpolate(original, BSpline(Linear()), OnGrid())
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Might want to dispatch to a version of imresize! that accepts original::AbstractInterpolation. That way if people want higher-order interpolation they can get it easily.

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Good idea

sf = map(/, size(original), size(resized))
for I in CartesianRange(size(resized))
I_o = map(*, I.I, sf)
resized[I] = itp[I_o...]
end
resized
end

38 changes: 19 additions & 19 deletions test/runtests.jl
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@@ -1,26 +1,26 @@
using ImageTransformations, CoordinateTransformations, TestImages, ImageCore, Colors, FixedPointNumbers
using Base.Test

#img = testimage("camera")
#tfm = recenter(RotMatrix(-pi/8), center(img))
#imgr = warp(img, tfm)
#@test indices(imgr) == (-78:591, -78:591)
img = testimage("camera")
tfm = recenter(RotMatrix(-pi/8), center(img))
imgr = warp(img, tfm)
@test indices(imgr) == (-78:591, -78:591)
#imgr2 = warp(imgr, inv(tfm)) # this will need fixes in Interpolations
#@test imgr2[indices(img)...] ≈ img

@testset "Restriction" begin
imgcol = colorview(RGB, rand(3,5,6))
A = reshape([convert(UInt16, i) for i = 1:60], 4, 5, 3)
B = restrict(A, (1,2))
Btarget = cat(3, [ 0.96875 4.625 5.96875;
2.875 10.5 12.875;
1.90625 5.875 6.90625],
[ 8.46875 14.625 13.46875;
17.875 30.5 27.875;
9.40625 15.875 14.40625],
[15.96875 24.625 20.96875;
32.875 50.5 42.875;
16.90625 25.875 21.90625])
Btarget = cat(3, [ 0.96875 4.625 5.96875;
2.875 10.5 12.875;
1.90625 5.875 6.90625],
[ 8.46875 14.625 13.46875;
17.875 30.5 27.875;
9.40625 15.875 14.40625],
[ 15.96875 24.625 20.96875;
32.875 50.5 42.875;
16.90625 25.875 21.90625])
@test B ≈ Btarget
Argb = reinterpret(RGB, reinterpret(N0f16, permutedims(A, (3,1,2))))
B = restrict(Argb)
Expand All @@ -31,12 +31,12 @@ using Base.Test
@test isapprox(reinterpret(eltype(eltype(B)), B), restrict(A, (2,3))/reinterpret(one(N0f16)), atol=1e-12)
A = reshape(1:60, 5, 4, 3)
B = restrict(A, (1,2,3))
@test cat(3, [ 2.6015625 8.71875 6.1171875;
4.09375 12.875 8.78125;
3.5390625 10.59375 7.0546875],
[10.1015625 23.71875 13.6171875;
14.09375 32.875 18.78125;
11.0390625 25.59375 14.5546875]) ≈ B
@test cat(3, [ 2.6015625 8.71875 6.1171875;
4.09375 12.875 8.78125;
3.5390625 10.59375 7.0546875],
[ 10.1015625 23.71875 13.6171875;
14.09375 32.875 18.78125;
11.0390625 25.59375 14.5546875]) ≈ B
#imgcolax = AxisArray(imgcol, :y, :x)
#imgr = restrict(imgcolax, (1,2))
#@test pixelspacing(imgr) == (2,2)
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