1.5 The complex wavelet approach

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A description of our algorithm for generating signatures.

Our basic approach remains the same as that proposed by Jacobs et al. We compute the signatures of images in the database and compare them to the signature of the query. However, we propose a novel method to compute the signatures:

• Compute the CDWT of the image and find the magnitudes of the coefficients.
• Set all but the highest magnitude coefficients to 0.
• Set the remaining coefficients to +1. (No way to use –1 since magnitudes of complex numbers are always positive).
• Compute the two-dimensional DFT of each subband.

After step 3, the signature matrices correspond to the major feature points in an image. The +1’s characterize the image structure. Note that due to the high degree shift-invariance offered by the CDWT, the signature of a shifted image after step 3 will just be a shifted version of the signature of the original image (after step 3). Now, computing the DFT in each subband gets rid of these shift effects, since the magnitude of the DFT of both the signatures (after step 3) will be the same. In this manner, our proposed algorithm incorporates the multiresolution characteristics of the CDWT in addition to accounting for translations in the query image. We compare signatures by computing the L1 norm of the difference between the signature of an image in the database and that of its query.

An implementation of our algorithm is available on Owlnet at

`~venkatc/elec301/tmproject/code/cdwt`

The m-file for generating signatures is `sig_gen.m` , and the metric function for comparing signatures is `metric.m` .

what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
how did you get the value of 2000N.What calculations are needed to arrive at it
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