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Lab 5: histogram equalization  (Page 5/2)

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Students will implement histogram equalization on the Android platform. Concepts include color conversion, histograms, cumulative distribution functions, and tone mappings.

Lab overview

In this lab, you will create an Android application that performs histogram equalization on streaming video, and deploy it on the Google Nexus 7 tablet. You will input a video stream from the front-facing camera, equalize each frame of video, and then display the equalized video on the screen alongside the unprocessed video.

Part 1: setting up android and eclipse

After completing Lab 4, you should be familiar with the Android development process, and you should feel comfortable working with Eclipse and the Nexus 7. This includes understanding the difference between Java and native C code, being able to compile and run your code on the tablet, and using both the Java and C debuggers to troubleshoot your code.

If you are not familiar with all of the above concepts, go back to Lab 4 and read the relevant sections.
  1. Start Cygwin by double-clicking on C:\NvPack\cygwin\cygwin.bat
  2. In the prompt, navigate to the Eclipse folder by typing cd /cygdrive/c/NvPack/eclipse
  3. Launch Eclipse with ./eclipse

Once Eclipse opens, select File>Import...

  1. General>Existing Projects into Workspace
  2. V:\ece420\nexus\OpenCV - 2.4.5
  3. V:\ece420\nexus\Lab5\
  4. Check "Copy into Workspace"

Additionally, in Lab5 Project Properties>Android , remove the current reference to the OpenCV library, which should have a red check mark next to it, and add the library that is in your workspace.

The lab machines currently do not support Android 4.2.2. If your tablet has upgraded, you have two options:

  • Get a TA to roll back your OS to 4.1.2. See this link for instructions.
  • Develop on your own machine by installing the latest Nvidia Tegra Development Pack.

For this lab project, the build process in Eclipse has already been configured to build everything automatically, and so building your project is as simple as clicking Project>Build Project .

You may want to uncheck Build Automatically , and then build by first Clean ing the project and checking the "Immediately start build" option.

The first time you run the application, you will be asked to download the OpenCV Manager from the Play Store; make sure you are connected to the internet.

Running the demo now will only stream video in grayscale. Pressing the ... in the corner of the screen will bring up the options menu, allowing you to view the RGB or equalized image; you will implement these functionalities in Parts 2 and 3.

Part 2: color conversion

In this part, you will implement your own color-conversion algorithm. The purpose is to obtain a better understanding of different color spaces, along with becoming more comfortable with accessing multidimensional data in an environment other than MATLAB.

As discussed in the prelab, there is more than one way to represent the pixels in an image. We will be applying histogram equalization in a color space known as YUV. The Y channel encodes the luma component (brightness), and the U and V are the chroma (color) components. The equalized image will be displayed in RGB.

Questions & Answers

what does the ideal gas law states
Joy Reply
Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
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Source:  OpenStax, Ece 420 spring 2014. OpenStax CNX. Jan 18, 2014 Download for free at http://cnx.org/content/col11618/1.3
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