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In Y C b C r , the luminance parameter is related to an overall intensity of the image.The chrominance components are a measure of the relative intensities of the blue and red components. The inverse of the transformation in [link] can easily be shown to be the following.

R = Y + 1 . 4025 ( C r - 128 ) G = Y - 0 . 3443 ( C b - 128 ) - 0 . 7144 * ( C r - 128 ) B = Y + 1 . 7730 ( C b - 128 )

Color exercise

Download the files girl.tif and ycbcr.mat . For help on image command select the link.

You will be displaying both color and monochrome images in the following exercises.Matlab's image command can be used for both image types, but care must be taken for the command to work properly.Please see the help on the image command for details.

Download the R G B color image file girl.tif , and load it into Matlab using the imread command. Check the size of the Matlab array for this image by typing whos . Notice that this is a three dimensional array of type uint8 . It contains three gray scale image planes corresponding to the red, green, andblue components for each pixel. Since each color pixel is represented bythree bytes, this is commonly known as a 24-bit image. Display the color image using

image(A);

axis('image');

where A is the 3-D R G B array.

You can extract each of the color components using the following commands.

RGB = imread('girl.tif'); % color image is loaded into matrix RGB

R = RGB(:,:,1); % extract red component from RGB

G = RGB(:,:,2); % extract green component from RGB

B = RGB(:,:,3); % extract blue component from RGB

Use the subplot and image commands to plot the original image, along with each of the three color components.Note that while the original is a color image, each color component separately is a monochrome image.Use the syntax subplot(2,2,n) , where n = 1 , 2 , 3 , 4 , to place the four images in the same figure.Place a title on each of the images, and print the figure(use a color printer).

We will now examine the Y C b C r color space representation. Download the file ycbcr.mat , and load it intoMatlab using load ycbcr . This file contains a Matlab array for a color image in Y C b C r format. The array containsthree gray scale image planes that correspond to the luminance ( Y ) and two chrominance ( C b C r ) components. Use subplot(3,1,n) and image to display each of the components in the same figure.Place a title on each of the three monochrome images, and print the figure.

In order to properly display this color image, we need to convert it to R G B format. Write a Matlab function that will perform the transformation of [link] . It should accept a 3-D Y C b C r image array as input, and return a 3-D R G B image array.

Now, convert the ycbcr array to an R G B representation and display the color image.Remember to convert the result to type uint8 before using the image command.

An interesting property of the human visual system, with respect to the Y C b C r color space, is that we are much more sensitive to distortion in the luminance component than in the chrominancecomponents. To illustrate this, we will smooth each of these components with a Gaussian filter and view the results.

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Damian Reply
absolutely yes
Daniel
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Maciej
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Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
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
Abhijith Reply
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?
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
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
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what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
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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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