Basic Plotting In MATLAB



Enjoyed our previous posts??
Now Do read us further for something like an Introduction about Plotting graphs in MATLAB
Well now, proceeding towards  the next step by graphically plotting your calculations and results. MATLAB  makes it easy for you to do so by just typing a few commands!! So what are you waiting for ?? … Let’s get started!!

Suppose you have a set of points to be plotted, for this you have to create two arrays (row or column vectors) namely X and Y (for example).

X  and Y contains the set of points corresponding to the X-axis and Y-axis respectively.

The command used fo this is "plot(x,y)"

Example:- You have to plot the following points (1,2),(2,3),(3,4),(4,5).

Then just do type it like this:-
>> X=[1 2 3 4] ;
>> Y=[2 3 4 5];
>> plot(X,Y)

Now See what plot you have obtained from that:-

MATLAB Plot of Graph
MATLAB Plot of Graph
 If you have obtained something like above, I must congratulate you that you did it. You have plotted a graph in the MATLAB using the X & Y axis value.


Let’s try to plot a simple function sin(x) in the interval [0,2π]. To get this done create a vector having the range of the values to be plotted .
Example:-

X varying from 0 to 2 π in the intervals of π/50.
>>X=0:pi/100:2 *π;
>>Y=sin(X);
>>plot(X,Y)
Lets See results!!
MATLAB Sine Plot Graph
MATLAB Sine Plot Graph

Now that are done with the basics of plotting we will move further in plotting. For that you need to hold on and be eager to read the next post (coming soon)!!
Hope you learnt a new thing from this…
Please drop on your comments below.

Pulkit Khandelwal,
VIT University ,Vellore.

An Introduction To Retinal Scanning and Iris Scan


Introduction To Retinal Scanning and Iris Scan

Retinal scanning is the analysis of the blood vessels at the back of the eye whereas Iris scanning takes a reading of the characteristics of the iris.Scanning involves a low-intensity light and an coupler to read different  patterns.
Points of reference used in an iris pattern as a basis for a match are 240 while fingerprints uses about 60.

Known Facts

The left eye and right eye are not the same on one person,and even identical twins (who shares the same DNA pattern) have different iris patterns.The iris scanning has  six times more distinct identifiable features than fingerprints.The probability of having two irises alike are one in ten to the 78th power (the population of the earth is approx. ten to the tenth power). Glasses or contact lenses do not interfere with the operation of iris recognition,and there is no possible known way of copying a retina.

Retina
Eye Structure
Eye Structure

The human retina is a thin tissue composed of neuralcells that is located in the posterior portion of the eye. Because of the complex structure of the capillaries that supply the retina with blood, each person’s retina is unique. The network of blood vessels in the retina is complex, although retinal patterns may be altered in cases of diabetes, & other medical disorders, the retina typically remains unchanged from birth until death.
Retinal scanning also has any medical applications. Communicable illnesses such as AIDS, syphilis, malaria, chicken pox well as hereditary diseases like leukemia, lymphoma, and sickle cell anemia impact the eyes. Pregnancy also affects the eyes. Likewise, indications of chronic health conditions such as congestive heart failure, atherosclerosis, and cholesterol issues first appear in the eyes.

 Iris           
It is a  circular structure in the eye, responsible for controlling the diameter and size of the pupils and amount of light reaching the retina. “Eye color” is the color of the iris, which can be green, blue, or brown. Iris recognition is an automated method of biometric identification that uses mathematical pattern-recognition techniques on video images of the irises of an eye.
                                                    
                   
IRIS Scan On Work
IRIS Scan On Work
                              

How Does Retinal Scanning Works
Blood vessels on the retina are known to absorb the infrared light faaster than the surrounding eye tissues so a low intensity infrared light is used ,the light is reflected back to  a video camera which takes 2 seconds to scan the pattern.Then the pattern of blood vessels are converted to mathematical patterns , which is then fed to computer(stored data).

                                                     
Shortcomings
Iris scanners can be easily fooled by a high quality image of an iris or face in place of the real thing.
It is usually difficult to adjust scanners for different hieghts person’s if there irises pictures are to be captured in succession.
Iris recognition is very difficult to perform at a distance larger than a few meters and if the person to be identified is not cooperating by holding the head still and looking into the camera.
Researchers have tricked iris scanners using images generated from digital codes of stored irises. Criminals could exploit this flaw to steal the identities of others.
Alcohol consumption causes recognition degradation as the pupil dilates/constricts causing deformation in the iris pattern.

Iris recognition in fiction
In Demolition Man(1993), a character played by Wesley Snipes uses the Warden's gouged eye to gain access through a security door.
In Dan Brown’s 2000 novel Angels and Demons an assassin gains access to a top secret CERN laboratory using a scientist's eye using retina scan.
Steven Spielberg's 2002 science fiction film Minority Report depicts a society in which what appears to be a form of iris recognition has become daily practice. 


An Article By Ajay Rai
VIT Universty