3D Data Denoising via Nonlocal Means Filter by Using Parallel GPU Strategies

Algorithm 1

Pseudocode of the NLM algorithm.

(1)  for  each voxel (𝑖₁,𝑖₂,𝑖₃) of the 3D image to be filtered do

(2)    Initialize the cumulative sum of weights and the restored value to 0;

(3)    for  each voxel (𝑗₁,𝑗₂,𝑗₃) of the search window 𝑉_{(𝑖1,𝑖2,𝑖3)}  do

(4)      for  each voxel (𝑘₁,𝑘₂,𝑘₃) of the similarity window _{(𝑗1,𝑗2,𝑗3)}𝐵_{(𝑖1,𝑖2,𝑖3)}  do

(5)       Cumulate squared Euclidean distance;

(6)      end  for

(7)      Calculate and cumulate the weight of the voxel in search window;

(8)      Cumulate the restored value;

(9)       end  for

(10)    Normalize restored value to the sum of the weights;

(11)     end  for