You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: algo_SB_proxA_2D.m
    path of file: ./repos/CS_MoCo_LAB/reconstruction/matlab/CS_LAB_matlab/@Proximal
    
    the code of the file until where you have to start completion: function [imageCha, ssim_map, metrics] = algo_SB_proxA_2D( obj,input )
% 2D variant of SB
% based on Goldstein and Oshers paper on Split Bregman
%

    
function [imageCha, ssim_map, metrics] = algo_SB_proxA_2D( obj,input )
% 2D variant of SB
% based on Goldstein and Oshers paper on Split Bregman
%
% input:
% obj           CS reconstruction object (holding all parameters)
% input         struct containing recon parameters and image
%
% output:
% imageCha      reconstructed channel individual image
% ssim_map      structural similarity map
% metrics       evaluation metrics 
%
% (c) Marc Fischer, Thomas Kuestner, May 2015
% -------------------------------------------------------------------------

%%
timer_proxA = tic;

%% variables:
% internal flags
flag_wavetree = true;
flag_fast = true;
flag_extend