Workshop proceeding - final.pdf - Faculty of Information and ...
Workshop proceeding - final.pdf - Faculty of Information and ...
Workshop proceeding - final.pdf - Faculty of Information and ...
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speed, several methods can be utilized. Here we use the changeable resolution algorithm to accelerate<br />
it. The key step <strong>of</strong> the changeable resolution algorithm is to reduce the resolution at first, then roughly<br />
do image registration in the lower resolution images, <strong>and</strong> then do it accurately near the possible<br />
positions in the full resolution images, <strong>final</strong>ly we can get the registration results.<br />
Optical image<br />
IR image<br />
Edge extraction<br />
Edge extraction<br />
Resolution Reducing<br />
Resolution Reducing<br />
NCC<br />
Roughly registration<br />
NCC at certain positions<br />
Selecting optimal position<br />
Rotation angle estimation<br />
Image registration parameters<br />
Fig 1 Flow diagram <strong>of</strong> changeable resolution algorithm based on NCC<br />
Suppose Im O <strong>and</strong> Im IR (image size is M×N) st<strong>and</strong>s for the optical <strong>and</strong> IR image respectively, f is<br />
the image zoom factor, Im Ol <strong>and</strong> Im IRl (image size is Mh×Nh) st<strong>and</strong>s for the lower resolution one,<br />
accordingly, Im Oe , Im IRe , Im Ole , Im IRle are the edged images <strong>of</strong> the corresponding images, then the<br />
generalize cross correlation can be expressed as<br />
ρ ( u,<br />
v)<br />
=<br />
l<br />
ρ(<br />
k,<br />
l)<br />
=<br />
Mh<br />
Nh<br />
∑∑<br />
i= 0 j=<br />
0<br />
M<br />
N<br />
∑∑<br />
i= 0 j=<br />
0<br />
(Im<br />
(Im<br />
Oleu, v<br />
( i,<br />
j)<br />
− ImIRle<br />
( i,<br />
j))<br />
σ<br />
lu,<br />
v<br />
k , l<br />
σ<br />
IR<br />
IRl<br />
Oek, l<br />
( i,<br />
j)<br />
− ImI<br />
Re<br />
( i,<br />
j))<br />
σ<br />
σ<br />
Where ρ<br />
l<br />
( u,<br />
v)<br />
is the cross correlation coefficient calculated from the lower resolution image pair<br />
Im Ole <strong>and</strong> Im IRle , (u,v) is the coordinate index <strong>of</strong> the optical image Im Ole , Im Oleu,v<br />
is an image located in<br />
(u,v)th <strong>of</strong> the image Im Ole <strong>and</strong> its size is the same as image Im IRle , σ lu,v <strong>and</strong> σ IRl are the st<strong>and</strong>ard<br />
deviation <strong>of</strong> the corresponding images respectively; ρ ( k,<br />
l)<br />
is the cross correlation coefficient<br />
calculated from the raw resolution image pair Im Oe <strong>and</strong> Im IRe , (k,l) is the coordinate index <strong>of</strong> the<br />
(1)<br />
(2)<br />
28