matlab特征匹配部分程序整理

Affine

function img2 = affine(img, r, sx, sy, a, b, xo, yo)

R = [cos(r) -sin(r) 0;

sin(r) cos(r) 0;

0 0 1];

S = [sx a 0;

b sy 0;

0 0 1];

T2 = [1 0 -xo;

0 1 -yo;

0 0 1];

T1 = [1 0 xo;

0 1 yo;

0 0 1];

A = T1*R*S*T2;

[h,w]=size(img);

[x,y] = meshgrid(1:h,1:w);

x=x(:);

y=y(:);

XP = [x';y';ones(1,length(x))];

X = A*XP;

z = find(X(1,:)>w-1);

X(1,z) = w-1;

z = find(X(1,:)<=1);

X(1,z) = 1.5;

z= find(X(2,:)>h-1);

X(2,z) = h-1;

z= find(X(2,:)<1.5);

X(2,z) = 1.5;

x = X(1,:);

y = X(2,:);

alpha = x - floor(x); %calculate alphas and betas for each point

beta = y - floor(y);

fx = floor(x); fy = floor(y);

inw = fy + (fx-1)*h; %create index（索引）for neighboring pixels ine = fy + fx*h;

isw = fy+1 + (fx-1)*h;

ise = fy+1 + fx*h;

img2 = (1-alpha).*(1-beta).*img(inw) + ... %interpolate（同样）(1-alpha).*beta.*img(isw) + ...

alpha.*(1-beta).*img(ine) + ...

alpha.*beta.*img(ise);

img2 = reshape(img2,h,w);

imagesc(img2);

%build_pyramid

function [pyr,imp] = build_pyramid(img,levels,scl)

img2 = img;

img2 = resample_bilinear(img2,1/2); %expand to retain spatial frequencies %img2 = imresize(img2,2,'bilinear'); %expand to retain spatial frequencies sigma=1.5; %variance for laplacian filter

sigma2=1.5; %variance for downsampling

sig_delta = (1.6-.6)/levels;

for i=1:levels

if i==1

img3 = img2;

img2 = filter_gaussian(img2,7,.5); %slightly filter bottom level end

imp{i}=img2;

A = filter_gaussian(img2,7,sigma); %calculate difference of gaussians

B = filter_gaussian(A,7,sigma);

pyr{i} = A-B; %store result in cell array

if i==1

img2 = img3;

else

B = filter_gaussian(img2,7,sigma2); %anti-alias for downsampling

B = filter_gaussian(B,7,sigma2);

end

img2 = resample_bilinear(B,scl); %downsample for next level

end

%show_pyramid(pyr) %show pyramid if desired

%///////////////////////////////////////////////////////////////////////////////

function show_pyramid(pyr)

close all

[h,w] = size(pyr);

for i=1:

figure

imagesc(pyr{i});

colormap gray;

end

3\

function key = construct_key(px, py, img, sz)

pct = .75;

[h,w] = size(img);

[yoff,xoff] = meshgrid(-1:1,-1:1);

yoff = yoff(:)*pct;

xoff = xoff(:)*pct;

for i = 1:size(yoff,1)

ctrx = px + xoff(i)*sz*2; %method using interpolated values