% BRIGHTENIING:

% brighten images

image = testImage;

method = 3;

filePath = 'C:\Documents and Settings\Kim Shultz\My Documents\ee362\brightened pictures\';

fileName = cat(2,filePath,'test_image.jpg');

% methods are as follows:

% 1 = make mean 0.5 by addition

% 2 = make mean 0.5 by multiplication

% 3 = multiply by exponential decay

% 4 = multiply by gaussian

if method == 1;

Rav = mean(image(:,:,1));

Rav = mean(Rav);

Gav = mean(image(:,:,2));

Gav = mean(Gav);

Bav = mean(image(:,:,3));

Bav = mean(Bav);

av = mean([Gav,Bav,Rav]);

image = image +0.5 - av;

%if any values are over 1, cutoff at 1

image = min(image,1);

%if any values are under 0, cutoff at 0

image = max(image,0);

end

if method == 2;

Rav = mean(image(:,:,1));

Rav = mean(Rav);

Gav = mean(image(:,:,2));

Gav = mean(Gav);

Bav = mean(image(:,:,3));

Bav = mean(Bav);

av = mean([Gav,Bav,Rav]);

image = image*0.5/av;

%if any values are over 1, cutoff at 1

image = min(image,1);

%if any values are under 0, cutoff at 0

image = max(image,0);

end

if method == 3

x = .1;

y = 3;

image(:,:,1) = image(:,:,1).*y.*(exp(-mean(image,3)/x)+1/y-exp(-1/x));

image(:,:,2) = image(:,:,2).*y.*(exp(-mean(image,3)/x)+1/y-exp(-1/x));

image(:,:,3) = image(:,:,3).*y.*(exp(-mean(image,3)/x)+1/y-exp(-1/x));

%if any values are over 1, cutoff at 1

image = min(image,1);

%if any values are under 0, cutoff at 0

image = max(image,0);

end

if method == 4

x = .2;

y = 2;

xx = [0:.01:1];

yy = y.*(exp(-(xx./x).^2)+1/y-exp(-1/x^2));

image(:,:,1) = image(:,:,1).*y.*(exp(-(mean(image,3)./x).^2)+1/y-exp(-1/x^2));

image(:,:,2) = image(:,:,2).*y.*(exp(-(mean(image,3)./x).^2)+1/y-exp(-1/x^2));

image(:,:,3) = image(:,:,3).*y.*(exp(-(mean(image,3)./x).^2)+1/y-exp(-1/x^2));

%if any values are over 1, cutoff at 1

image = min(image,1);

%if any values are under 0, cutoff at 0

image = max(image,0);

end

imwrite(image,fileName,'jpeg');