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image(B);

colormap(gray(256));

axis('image');

The image command works for both type uint8 and double images. The colormap command specifies the range of displayed gray levels, assigning black to 0 and white to 255.It is important to note that if any pixel values are outside the range 0 to 255 (after processing), they will be clipped to 0 or 255 respectivelyin the displayed image. It is also important to note that a floating point pixel value will berounded down ("floored") to an integer before it is displayed. Therefore the maximum number of gray levels that will be displayed onthe monitor is 255, even if the image values take on a continuous range.

Now we will practice some simple operations on the yacht.tif image. Make a horizontally flipped version of the image by reversing theorder of each column. Similarly, create a vertically flipped image. Print your results.

Now, create a "negative" of the image by subtracting each pixel from 255 (here's an example of where conversion to double is necessary.) Print the result.

Finally, multiply each pixel of the original image by 1 . 5 , and print the result.

Inlab report

  1. Hand in two flipped images.
  2. Hand in the negative image.
  3. Hand in the image multiplied by factor of 1.5. What effect did this have?

Pixel distributions

Download the files house.tif and narrow.tif for the following sections.

Histogram of an image

Histogram of an 8-bit image

The histogram of a digital image shows how its pixel intensities are distributed. The pixel intensities vary along the horizontal axis,and the number of pixels at each intensity is plotted vertically, usually as a bar graph.A typical histogram of an 8-bit image is shown in [link] .

Write a simple Matlab function Hist(A) which will plot the histogram of image matrix A . You may use Matlab's hist function, however that function requires a vector as input.An example of using hist to plot a histogram of a matrix would be

x=reshape(A,1,M*N);

hist(x,0:255);

where A is an image, and M and N are the number of rows and columns in A . The reshape command is creating a row vector out of the image matrix, and the hist command plots a histogram with bins centered at [ 0 : 255 ] .

Download the image file house.tif , and read it into Matlab.Test your Hist function on the image. Label the axes of the histogram and give it a title.

Hand in your labeled histogram. Comment on the distribution of the pixel intensities.

Pointwise transformations

Pointwise transformation of image

A pointwise transformation is a function that maps pixels from one intensity to another.An example is shown in [link] . The horizontal axis shows all possible intensitiesof the original image, and the vertical axis shows the intensities of the transformed image. This particular transformation maps the"darker" pixels in the range [ 0 , T 1 ] to a level of zero (black), and similarly maps the "lighter" pixels in [ T 2 , 255 ] to white. Then the pixels in the range [ T 1 , T 2 ] are "stretched out" to use the full scale of [ 0 , 255 ] . This can have the effect of increasing the contrast in an image.

Pointwise transformations will obviously affect the pixel distribution, hence they will change the shape of the histogram.If a pixel transformation can be described by a one-to-one function, y = f ( x ) , then it can be shown that the input and output histograms are approximately related by the following:

Questions & Answers

how can chip be made from sand
Eke Reply
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Purdue digital signal processing labs (ece 438). OpenStax CNX. Sep 14, 2009 Download for free at http://cnx.org/content/col10593/1.4
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