function?[outImwhatScaleDirection]?=?FrangiFilter2D（I?options）??
%?This?function?FRANGIFILTER2D?uses?the?eigenvectors?of?the?Hessian?to??
%?compute?the?likeliness?of?an?image?region?to?vessels?according??
%?to?the?method?described?by?Frangi:2001?（Chapter?2）.??
%?[JScaleDirection]?=?FrangiFilter2D（I?Options）??
%?inputs??
%???I?:?The?input?image?（vessel?image）??
%???Options?:?Struct?with?input?options??
%???????.FrangiScaleRange?:?The?range?of?sigmas?used?default?[1?8]??
%???????.FrangiScaleRatio?:?Step?size?between?sigmas?default?2??
%???????.FrangiBetaOne?:?Frangi?correction?constant?default?0.5??
%???????.FrangiBetaTwo?:?Frangi?correction?constant?default?15??
%???????.BlackWhite?:?Detect?black?ridges?（default）?set?to?true?for??
%???????????????????????white?ridges?set?to?false.??
%???????.verbose?:?Show?debug?information?default?true??
%?outputs??
%???J?:?The?vessel?enhanced?image?（pixel?is?the?maximum?found?in?all?scales）??
%???Scale?:?Matrix?with?the?scales?on?which?the?maximum?intensity???
%???????????of?every?pixel?is?found??
%???Direction?:?Matrix?with?directions?（angles）?of?pixels?（from?minor?eigenvector）?????
%??
%?Written?by?Marc?Schrijver?2/11/2001??
%?Re-Written?by?D.Kroon?University?of?Twente?（May?2009）??
??
defaultoptions?=?struct（‘FrangiScaleRange‘?[1?5]?‘FrangiScaleRatio‘?2?‘FrangiBetaOne‘?0.5?‘FrangiBetaTwo‘?15?‘verbose‘true‘BlackWhite‘true）;??
??
%?Process?inputs??
if（~exist（‘options‘‘var‘））???
????options=defaultoptions;???
else??
????tags?=?fieldnames（defaultoptions）;??
????for?i=1:length（tags）??
?????????if（~isfield（optionstags{i}））??options.（tags{i}）=defaultoptions.（tags{i}）;?end??
????end??
????if（length（tags）~=length（fieldnames（options）））???
????????warning（‘FrangiFilter2D:unknownoption‘‘unknown?options?found‘）;??
????end??
end??
??
%sigam范圍從FrangiScaleRange（1）到FrangiScaleRange（2），步長為FrangiScaleRatio，具體要結合圖像??
??
sigmas=options.FrangiScaleRange（1）:options.FrangiScaleRatio:options.FrangiScaleRange（2）;??
sigmas?=