Filters are operations where the value of each pixel depends on some neighbourhood of that pixel. Blurring and edge detection are good examples.
Methods
void blur(int size,int times)
blur the image: smoothen transitions and remove edges.
size is the size of the filter: a larger filter gives more blur.
times is the number of times filtering must take place. Filtering a number of times gives more blur. If you don't know what to do, choose size and times equal, for instance 3 or 5.
out.blur(3,3); 

double[][] newblurfilter(int sx,int sy)
Create a blurfilter that can be used in convolute.
void convolute(double[][] d, boolean evenodd)
apply a linear filter to the image. d a matrix of coefficients. The numbers
in it can be positive or negative, and preferrably add up to 1.
boolean evenodd: does not matter if you are filtering once or with an oddsized filter. If you repeatedly filter with an evensized filter, let it switch: true, false, true, false, ...
void scatter(int hsize,int vsize)
apply a distortion that moves pixels around
out.scatter(10,10); 

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