%?-----------------------------------------------------------------------
%?
%?This?function?uses?the?SUSAN?algorithm?to?find?edges?within?an?image
%?
%
%?>>image_out?=?susan（image_inthreshold）
%
%
%?Input?parameters?...?The?gray?scale?image?and?the?threshold?
%?image_out?..?（class:?double）?image?indicating?found?edges
%?typical?threshold?values?may?be?from?10?to?30
%
%
%The?following?steps?are?performed?at?each?image?pixel:?
%?（?from?the?SUSAN?webpage?http://www.fmrib.ox.ac.uk/~steve/susan/susan/node4.html?）
%?
%?Place?a?circular?mask?around?the?pixel?in?question.?
%?Calculate?the?number?of?pixels?within?the?circular?mask?which?have?similar?brightness?to?
%?the?nucleus.?These?define?the?USAN.?
%?Subtract?USAN?size?from?geometric?threshold?to?produce?edge?strength?image.?
%
%?Estimating?moments?to?find?the?edge?direction?has?not?been?implemented?.?
%?Non-maximal?suppresion?to?remove?weak?edges?has?not?been?implemented?yet.
%
%?example:
%
%?>>?image_in=imread（‘test_pattern.tif‘）;
%?>>?image?=?susan（image_in27）;
%?>>?imshow（image[]）?
%
%
%?Abhishek?Ivaturi
%?
%?-------------------------------------------------------------------------

function?image_out?=?susan（imthreshold）

close?all

clc

%?check?to?see?if?the?image?is?a?color?image...
d?=?length（size（im））;
if?d==3
????image=double（rgb2gray（im））;
elseif?d==2
????image=double（im）;
end

%?mask?for?selecting?the?pixels?within?the?circular?region?（37?pixels?as
%?used?in?the?SUSAN?algorithm

mask?=?（[?0?0?1?1?1?0?0?;0?1?1?1?1?1?0;1?1?1?1?1?1?1;1?1?1?1?1?1?1;1?1?1?1?1?1?1;0?1?1?1?1?1?0;0?0?1?1?1?0?0]）;



%?the?outpu