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A description of the actual comparison process of FFT from the input image vs. image in the database. Also, construction of the database.

So, now we have an FFT of the coin. What are we going to compare it to? A pre-created database of course! Thedatabase creation steps are pretty straightforward, but there are a number of reasons for developing a streamlined approach toit.

Database creation

You could create the database manually by taking subsets of the input picture matrix and performing theunwrapping on them manually. Manual database editing might be feasible if you only had 10 coins to recognize. However,considering that the United States has minted coins for all fifty states in addition to entries for dirty coins and differentlighting conditions, you’ll probably want to simplify the process. What we did was basically take our full code and hack it off beforethe unwrapping process. The radii and centers go into a function that displays the image of the coin to the user. The user thenenters in values for the metadata associated with that image. In our case we used heads/tails, value in USD, coin name, andabbreviated coin descriptor (for debugging). We created a graphical interface in Matlab for loading images and loading and savingdatabase files.

Coin input gui

The coin input GUI we developed.


The resulting database should contain the metadata and the precomputed FFTs of the already unwrapped coins.The code then takes each input FFT and compares it to each stored FFT. There are many different algorithms to determine the“closeness”of two FFTs.

Dot product

You can normalize each line of the FFT, and then do a vector dot product with the corresponding line in theother FFT. Then you take the average value of the resulting one-line vector. If the two FFTs are identical, they will return avalue of 1. Depending on how different they are, the number will be something between 0 and 1.

Sum of differences

You can take the FFTs, subtract them from each other, take the absolute value, and sum all of the resultingdifferences. Two identical matrices will return a value of 0. If the matrices are at all different, the sum will be greater thanzero.

In our implementation we found the dot product approach to work best, though any number of matrixcomparison algorithms could work. Once all of the FFTs have been identified, they should return the metadata to be displayed to theuser.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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.
what is the actual application of fullerenes nowadays?
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Elec 301 projects fall 2006. OpenStax CNX. Sep 27, 2007 Download for free at http://cnx.org/content/col10462/1.2
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