LDR_reconstruction.m

function out = LDR_reconstruction(im,sigmaRN,T,B,denoise) 
% Authors : Abhiram Gnanasambandam (agnanasa@purdue.edu),
%Stanley H. Chan (stanchan@purdue.edu)
%Intelligent Imaging Lab, Dept. of ECE, Purdue University
% Reference:
%[1]HDR Imaging with Quanta Image Sensors: Theoretical Limits and Optimal
%Reconstruction, Abhiram Gnanasambandam and Stanley H. Chan, 
%IEEE Transactions on Computational Imaging, 2020
%[2]High Dynamic Range Imaging using Quanta Image Sensors, Abhiram
%Gnansambandam, Jiaju Ma, Stanley H. Chan, IISW 2019.
% This function reconstructs LDR QIS images
%im - Noisy sum of static QIS data
%sigmaRN - Read noise of the sensor
% T - Number of frames summer to get T
% B - Non-linear mapping corresponding to q-bit QIS.
% denoise - use BM3D denoiser if denoise = 1.

    addpath('utils/denoisers')
    if denoise == 1
        im = 2 * sqrt(im + 3/8 + T * sigmaRN^2);
        maxi = max(im(:));
        mini = min(im(:));
        im = (im - mini)/(maxi-mini);
        im = wrapper_BM3D(im,1/(maxi-mini))*(maxi-mini) + mini ;
        im = (im/2).^2 - 1/8 - T * sigmaRN^2;
        im(im<0) = 0;
        im(im>max(im(:))) = max(im(:));
    end

    im = im/T;
    out = B(im);
end