LIME: Low-Light Image Enhancement via Illumination Map Estimation

This is a MATLAB implementation of the paper, "LIME: Low-Light Image Enhancement via Illumination Map Estimation". It has been done as a course Capstone project for Digital Image Processing (EE60062), under the guidance of Prof. Debdoot Sheet.

• The project report can be found here.
• The IEEE reference paper can be found here

How to Use

Clone the repository:

git clone https://github.com/YASHANAND23IITKGP/LIME_IMAGE-_PROCESSING

  Open MATLAB, go to the git repository folder.

Add paths

  Run the following to the MATLAB command window:

addpath('./imgs');

Load images and run

  Run the following commands in the MATLAB command window:

img_in = imread('x.bmp'); 
[Ti, Tout, img_out, Iout] = lime_main_module(img_in, mu, rho, ds, ss, flag);

• x is some image from imgs
• flag = 1 to view the results.
• Ti and Tout are initial and refined illumination maps, img_out and Iout are enhanced and denoised results.
• Use the table mentioned below for selecting optimum values of mu, rho, ds, ss for each image.

Table for optimized hyperparameters

Name	mu	rho	ds	ss
building	0.01	1.188	10	1.5
cars	0.045	1.134	5	0.75
lamp	0.8	1.07	0.1	1
land	0.5	1.09	0.3	4
moon	0.01	1.2	1	0.5
paint	0.3	1.15	1	0.5
robot	0.01	1.25	10	1
table	0.002	1.035	100	1
wires	0.01	1.165	1	0.6

Information regarding other files:

• lime_loop.m is the file for tuning the parameters for the solver, i. e. alpha, mu, rho.

• lime_bf_loop.m is the file for tuning the parameters for the bilateral filter, i. e. ds, ss. By default, lime_bf_loop.m is used for post-processing.

• initial_map.m is the file for obtaining initial illumination map.

• gamma_corr.m is the file for applying gamma correction.

• make_weight_matrix.m is the file for making the weight matrix.

• shrinkage.m is the file for performing shrinkage operation.

• updateT.m is the file for updating the value of illumination map.

• maked_alt.m is the file for creating the matrix D for calculating gradient using matrix multiplication.

Results

First column: Low-light images, second column: heat map of initial illumination map, third column: heat map of estimated illumination map, fourth column: enhanced results, fifth column: denoised results via bilateral filtering.

Citation

If you find this code helpful and use it in your research, please cite the following work:

@ARTICLE{guo_lime,
  author={X. {Guo} and Y. {Li} and H. {Ling}},
  journal={IEEE Transactions on Image Processing}, 
  title={LIME: Low-Light Image Enhancement via Illumination Map Estimation}, 
  year={2017},
  volume={26},
  number={2},
  pages={982-993},}

Contributors

• @KAUSHALKISHOR9939
• @atulsaurabh1995