--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/PET/AlgorithmZeroDual.jl Sun Apr 21 13:43:18 2024 +0300
@@ -0,0 +1,181 @@
+####################################################################
+# Predictive online PDPS for optical flow with known velocity field
+####################################################################
+
+__precompile__()
+
+module AlgorithmZeroDual
+
+identifier = "pdps_known_zerodual"
+
+using Printf
+
+using AlgTools.Util
+import AlgTools.Iterate
+using ImageTools.Gradient
+using ImageTools.Translate
+
+using ..Radon
+using ImageTransformations
+using Images, CoordinateTransformations, Rotations, OffsetArrays
+using ImageCore, Interpolations
+
+using ..OpticalFlow: ImageSize,
+ Image,
+ petpdflow!
+
+#########################
+# Iterate initialisation
+#########################
+
+function init_rest(x::Image)
+ imdim=size(x)
+ y = zeros(2, imdim...)
+ Δx = copy(x)
+ Δy = copy(y)
+ x̄ = copy(x)
+ radonx = copy(x)
+ return x, y, Δx, Δy, x̄, radonx
+end
+
+function init_iterates(xinit::Image)
+ return init_rest(copy(xinit))
+end
+
+function init_iterates(dim::ImageSize)
+ return init_rest(zeros(dim...))
+end
+
+#########################
+# PETscan related
+#########################
+function petvalue(x, b, c)
+ tmp = similar(b)
+ radon!(tmp, x)
+ return sum(@. tmp - b*log(tmp+c))
+end
+
+function petgrad!(res, x, b, c, S)
+ tmp = similar(b)
+ radon!(tmp, x)
+ @. tmp = S .- b/(tmp+c)
+ backproject!(res, S.*tmp)
+end
+
+function proj_nonneg!(y)
+ @inbounds @simd for i=1:length(y)
+ if y[i] < 0
+ y[i] = 0
+ end
+ end
+ return y
+end
+
+############
+# Algorithm
+############
+
+function solve( :: Type{DisplacementT};
+ dim :: ImageSize,
+ iterate = AlgTools.simple_iterate,
+ params::NamedTuple) where DisplacementT
+
+ ################################
+ # Extract and set up parameters
+ ################################
+ α, ρ = params.α, params.ρ
+ R_K² = ∇₂_norm₂₂_est²
+ γ = 1
+ L = params.L
+ τ₀, σ₀ = params.τ₀, params.σ₀
+ τ = τ₀/L
+ σ = σ₀*(1-τ₀)/(R_K²*τ)
+
+ println("Step length parameters: τ=$(τ), σ=$(σ)")
+
+ λ = params.λ
+ c = params.c*ones(params.radondims...)
+
+
+ ######################
+ # Initialise iterates
+ ######################
+
+ x, y, Δx, Δy, x̄, r∇ = init_iterates(dim)
+
+ if params.L_experiment
+ oldpetgradx = zeros(size(x)...)
+ petgradx = zeros(size(x))
+ oldx = ones(size(x))
+ end
+
+ ####################
+ # Run the algorithm
+ ####################
+
+ v = iterate(params) do verbose :: Function,
+ b :: Image, # noisy_sinogram
+ v_known :: DisplacementT,
+ theta_known :: DisplacementT,
+ b_true :: Image,
+ S :: Image
+
+ ###################
+ # Prediction steps
+ ###################
+
+ petpdflow!(x, Δx, y, Δy, v_known, theta_known, false)
+ y .= zeros(size(y)...)
+
+ if params.L_experiment
+ @. oldx = x
+ end
+
+ ############
+ # PDPS step
+ ############
+
+ ∇₂ᵀ!(Δx, y) # primal step:
+ @. x̄ = x # | save old x for over-relax
+ petgrad!(r∇, x, b, c, S) # | Calculate gradient of fidelity term
+
+ @. x = x-(τ*λ)*r∇-τ*Δx # |
+ proj_nonneg!(x) # | non-negativity constaint prox
+ @. x̄ = 2x - x̄ # over-relax: x̄ = 2x-x_old
+ ∇₂!(Δy, x̄) # dual step:
+ @. y = y + σ*Δy # |
+ proj_norm₂₁ball!(y, α) # | prox
+
+ #####################
+ # L update if needed
+ #####################
+ if params.L_experiment
+ petgrad!(petgradx, x, b, c, S)
+ petgrad!(oldpetgradx, oldx, b, c, S)
+ if norm₂(x-oldx)>1e-12
+ L = max(0.9*norm₂(petgradx - oldpetgradx)/norm₂(x-oldx),L)
+ println("Step length parameters: L=$(L)")
+ τ = τ₀/L
+ σ = σ₀*(1-τ₀)/(R_K²*τ)
+ end
+ end
+
+ ################################
+ # Give function value if needed
+ ################################
+
+ v = verbose() do
+ ∇₂!(Δy, x)
+ value = λ*petvalue(x, b, c) + params.α*norm₂₁(Δy)
+ value, x, [NaN, NaN], nothing, τ, σ
+ end
+
+ v
+ end
+
+ return x, y, v
+end
+
+end # Module
+
+