Noise in images

Noise is just another function that is combined with the original function to get a new – guess what – function

I(x,y) = I(x,y)+n(x,y)

Salt and pepper noise: random occurrences of black and white pixels
Impulse noise: random occurrences of white pixels
Gaussian noise: variations in intensity drawn from a Gaussian normal distribution

>> noise = randn(size(im)).*sigma;
>> output = im + noise;

dolphin = imread('dolphin.png');
bicycle = imread('bicycle.png');

diff = dolphin - bicycle;

abs_diff = abs(bicycle - dolphin);
imshow(abs_diff);

preserve image difference: uint8
・(a – b)+(b – a)
・Convert to floating point

pkg load image;

abs_diff2 = imabsdiff(dolphin, bicycle);
imshow(abs_diff2);