LSC(lens shading correction)

clc,clear,close all

%-------parameters of correction- ---------
filePath = ' images/1scRefIng. jpg' ;
side_ num =17:
% load org inage
image=imread(filePath) ;
[height, width] = size (image) ;
sideX = floor (height/side_ num) :
sideY=floor (width/side_ num) ;

% load gain of each channel
load(' ./src/ data/Gain. mat' )
%---------correction-------------
disImg = zeros(size (image)):
gainStepX = 0
gainStepY = 0:
gainTab = zeros(size (image));
for i = 1:height
　　for j = 1:width
　　　　gainStepX = floor(i / sideX) + 1:
　　　　if gainStepX > 16
　　　　　　gainStepX = 16
　　　　end
　　　　gainStepY = floor(j / sideY) + 1:
　　　　if gainStepY > 16
　　　　　　gainStepY =16
　　　　end
　　%get tht gain of the point by interpolation(Bilinear interpolation)
　　% f(x,y) = [f(1.0)-f(0, 0)]*x+[f(0, 1)-f(0, 0)]*y+[f(1.1)+f(0, 0)-f(1. 0)-f(0, 1)]*xy+f (0, 0)
　　gainTab(i, j)=(Gain(gainStepX+1, gainStepY) - Gain(gainStepX, gainStepY)) * (i - (gainStepX - 1) *sideX)/sideX +...
　　　　(Gain(gainStepX, gainStepY+1) - Gain (gainStepX, gainStepY)) *(j - (gainStepY - 1)*sideY)/sideY
　　　　(Gain(gainStepX+1, gainStepY+1) + Gain(gainStepX，gainStepY) - Gain(gainStepX+1, gainStepY)- Gain(gainStepX， gainStepY + 1))
　　　　*(i - (gainStepX - 1)*sideX)/sideX * (j - (gainStepY - 1) *sideY)/sideY + Gain(gainStepX, gainStepY) :
end
end
disImg = double(image) .* gainTab:

figure():
subplot (121) ; imshow(image):title(' org image' ):
subplot (122) :imshow (uint8(disImg));title(' corrected image' ):