clear;
close?all;
clc;

%%%%%%%%%%%%%%%%%%%%%%%%%
%%%Input?parameters%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%
MaskSize?=?3;
Sigma?=?5;???%（for?Gaussian）
Threshold?=?0.30;?%（building?brick?0.13?monkey?0.22?lena0.18?building?outline?）
%?ThresholdRatio?=?0;
ThresholdRatio?=?1e-40;

%==========================================================================
%===================Opening?the?files?of?images============================
%==========================================================================
[filename?pathname]=uigetfile（{‘*.jpg‘;...
????‘*.bmp‘;...
????‘*.gif‘;...
????‘*.png‘;...
????‘*.tif‘}...
????‘Open?the?files?of?images‘）;
if?filename~=0
????openfilename?=?strcat（pathnamefilename）;?%processing?diversified?forms?of?images
????eval（[‘info=imfinfo（‘‘‘openfilename?‘‘‘）;‘]）;
????switch?info.ColorType
????????case?‘truecolor‘
????????????eval（[‘RGB?=?imread（‘‘‘openfilename?‘‘‘）;‘]）;??%[X?map]?=?rgb2ind（RGB?256）;
????????????InImg?=?rgb2gray（RGB）;
????????????clear?RGB;
????????case?‘indexed‘
????????????eval（[‘[X?map]?=?imread（‘‘‘openfilename?‘‘‘）;‘]）;
????????????InImg?=?ind2gray（X?map）;
????????????clear?X;
????????case?‘grayscale‘
????????????eval（[‘InImg?=?imread（‘‘‘openfilename?‘‘‘）;‘]）;
????end
else
????return;
end
st?=?cputime;
%?subplot（211）;imagesc（InImg）;title（‘lotus?picture‘）;
InImg?=?double（InImg）;
[rows?cols]?=?size（InImg）;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%?Calculate?Filtered?Gradient
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

GausDer_x?=?ones（MaskSizeMaskSize）;
GausDer_y?=?ones（MaskSizeMaskSize）;
Amp=-1/sqrt（2*pi*Sigma）;
for?g_x=1:MaskSize;
????for?g_y=1:MaskSize;
????????x?=?g_x-（MaskSize+1）/2;
????????y?=?g_y-（MaskSize+1）/2;
????????GausDer_x（g_xg_y）=Amp*（x/Sigma^2）.*exp（-（x^2+y^2）/（2*Sigma^2））;
????????GausDer_y（g_xg_y）=Amp*（y/Sigma^2）.*exp（-（x^2+y^2）/（2*Sigma^2））;???%derivative?of?a?Gaussian
????end
end

GausDer_x（g_xg_y）?=?sum（sum（GausDer_x（g_xg_y）））;
GausDer_y（g_xg_y）?=?sum（sum（GausDer_x（g_xg_y）））;????%normalization

Img_gx?=?conv2（InImgGausDer_x‘same‘）;
Img_gy?=?conv2（InImgGausDer_y‘same‘）;

F?=?sqrt（Img_gx.*Img_gx+Img_gy.*Img_gy）;??%the?magnitude?of?the?gradient
D?=?atan（Img_gy./Img_gx）;?????????????????%edge?orientation?of?the?gradient
figure（1）;
subplot（121）;
imagesc（F）;
title（‘Gradient?Amplitude‘）;
subplot（122）;
imagesc（D）;
title（‘Gradient?Angle‘）;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%?Nonmaximum?suppression
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

EdgGrad?=?zeros（rows?cols）;
EdgDirc?=?zeros（rows?cols）;
for?i?=?2:?（rows-1）
????for?j?=?2:?（cols-1）
????????switch?fix（8*D（ij）/pi）
????????????case?0?????????????????????????????????????%?from?0?-?pi/8??and?7pi/8?-pi
??

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2018-06-09?14:05??53623196Cmp_vis_canny\
?????文件????????7315??2018-06-09?10:56??53623196Cmp_vis_canny\Cmp_vis_canny.m
?????文件???????30046??2018-06-09?11:00??53623196Cmp_vis_canny\edge?detection.jpg
?????文件??????460040??2018-06-09?10:59??53623196Cmp_vis_canny\edge?gradient.fig
?????文件??????136304??2018-06-09?11:00??53623196Cmp_vis_canny\edge?gradient.jpg
?????文件???????11914??2006-08-09?11:57??53623196Cmp_vis_canny\flower.jpg
?????文件?????2120064??2018-06-09?10:57??53623196Cmp_vis_canny\gradient.fig
?????文件??????147180??2018-06-09?11:00??53623196Cmp_vis_canny\gradient.jpg
?????文件???????26152??2018-06-09?10:21??53623196Cmp_vis_canny\lotus.jpg
?????文件???????25586??2018-06-09?11:01??53623196Cmp_vis_canny\untitled.jpg