Problem Solving Assignment 7

Due: Tuesday, Feb 17th, 11:59 pm

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There is one problem in this PSA.

Note 1: Besides writing the code there is an interview process required for this PSA. Your interview is worth 10% of the PSA grade and is done individually.

Note 2: You will be required to submit your result from in the class wiki. This will count for 5% of your PSA grade.

This homework requires skills from all Chapters up to Chapter 6.

1. Chromakey -- Write a program that uses at least 3 images to create a new image.
   • You will take a picture with at least one person wearing a colored T-shirt in front of a blue screen.
   • You will then find two pictures. One will be the background (to replace the blue screen) and one will replace the T-shirt. You could put the person in the picture in Hawaii by using the Hawaii background and give them a fractal colored T-shirt.
   • There is room for creativity. You can have multiple people in the image, or you could use a blue and a green sheet to provide two different backgrounds. The minimum required is replacing one background and one T-shirt.
   
   

Details

You must put a comment at the top of your code that specifies, for both you and your partner, your: real names, login names, and PIDs, And a two to four sentence description of the program (one description for each program).

Use a multi-line comment (/* */).

Comments are important. Code must be properly commented to receive full credit.

You must observe an 80 column limit. No line of your program may be longer than the 80th column on the screen.

chromaKey

Method: chromaKey

• For this project, you have a fairly large range of freedom to make your picture interesting. At the core, you are using the colors of pixels in the image to allow you to substitute pixels from other images. You will be able to take a picture of a person wearing a red (or other colored) shirt in front of a blue canvas and make the background (canvas) look like another locale (Hawaii, Big Bear, etc.) and their T-shirt have a new design (Tie-Dye, Star Wars, etc.).
• To perform this project these are the minimal requirements.
  • Add at least one method (to Picture.java) called chromaKeyColor where "Color" is the color you are replacing. This method will alter the calling object and take at least two parameters. One (or more) integer parameters providing the threshold values of red, blue, and/or green. The other parameter is a Picture which will be the picture you use when replacing pixels.
    • Example 1: void chromakeyBlue(int bluethreshold, Picture input). Any pixel in the calling object with a blue value greater than the bluethreshold is replaced with the corresponding pixel in input.
    • Example 2: void chromakeyBlack(int bluethresh, int redthresh, int greenthresh, Picture input). Any pixel in the calling object with ALL the RGB values less than the threshold is replaced with the corresponding pixel in input.
  • UPDATE!!! You may use other heuristics in addition to the threshold value. For example, you may want to check to see if the blue is over the threshold and if the blue value is greater than the red and the green components.

Testing your method (in an application):

• Create a new file called PSA7.java where you will write an application to test your methods. Start by copying in this code.
• REQUIREMENT You must use the picture that you and your partner took using the sheets in the lab as the source picture. The background and shirt pictures can be used from pictures in media sources or from the internet.
• IMPORTANT In order for the grader to grade your submission your code must work with different paths. To obtain each media file, do NOT use the file path or MediaPath functions. Copy the images you want to use for your final submission into the same folder as your code. Then ensure that the file path is simply "imagename.jpg". For example, if you want to use barbara.jpg, use
  • String fileName = "barbara.jpg";
  • Picture p = new Picture(fileName);
• Using the above method for creating pictures, you will open your three images.
• Show your original image (the picture of you in front of the blue screen).
• You will then call your chromakey method to change the background.
  • For example: If your background is a blue sheet, you would call chromakeyBlue on your picture and pass it the background picture and threshold. This will cause the blue pixels in your image be replaced with the background.
• You will then call your chromakey method to change the T-shirt color.
  • For example: If your T-shirt is green you would call chromakeyGreen on your picture and pass it the picture for the T-shirt and threshold. This will cause the green pixels in your image be replaced with the new T-shirt picture.
• UPDATE!!! You may also use a "source" Picture as a parameter to the second chromakey method. Let's say you replace your blue background with a scene from Star Wars. Then you want to replace the red in your shirt, but the lasers are also getting replaced. For this, the best thing to do is to pass the original "source" Picture (before any changes) as an additional parameter to the method. You would then check the "source" picture for red values and if they are red, replace the pixels in the calling object with the pixels from your T-shirt background.
• Finally, show your new picture!
• Lastly, You must post your resulting image on the wiki AND include the hyperlink to your wiki submission in your PSA7 comments.

CREATIVITY

• You are absolutely encouraged to be creative in this assignment, we expect some AWESOME looking pictures to be posted on the wiki!
• Make sure it looks good, this assignment shouldn't take too long, so we expect the final picture to look almost real.
• NOTE: It works well if your source picture is smaller then the other two, why is this?

How to turnin your homework electronically

Before turning in your files, rename all of the pictures you wish to use in this assignment picture1.jpg, picture2.jpg, etc for all pictures you are submitting. If you name them anything else, they will not be collected or turned in. Your methods can have the pictures hard coded in, but they should be hard coded as "picture1.jpg" etc so that the graders know what pictures should be used where and there is no confusion on why your code doesn't work. If you are confused on this, please ask a tutor.

When you submit, the bundle script will be expecting 10 pictures, if you only have 2 or 3 this is OK. You will get a warning saying you are missing files, but as long as you are sure you included all of the pictures you wanted to include, and as long as it says you aren't missing any java files, it it ok and you will not be marked down.

When you are ready to turn in your homework, first open a terminal window by right clicking on the empty area of your computer's desktop (have to use lab computers or remotely connect from your home computer using SSH or Putty) and select "Open a New Terminal". Then, run bundlePSA7 from your PSA7/bookClasses directory. Files are required to be submitted for PSA7:

• Picture.java
• PSA7.java
• Any jpgs you use in your assignment (should be named picture1.jpg, etc)

If you don't have one of these files present or have misspelled the name of one of these files, the bundle script will complain! Here you can see how you can run these commands:

-bash-2.05b$  cd ~/PSA7/bookClasses 

-bash-2.05b$  bundlePSA7 

Good; all required files are present:

        Picture.java
        PSA7.java
        Any jpgs you used (should be named picture1.jpg, etc)

Do you want to go ahead and turnin these files? [y/n] y

OK.  Proceeding.


Performing turnin of approx. XXXX bytes
Copying to /home/linux/ieng6/cs8f/turnin.dest/cs8wxx.PSA7
.
Done.
Total bytes written: XXXX
Please check to be sure that's reasonable.
Turnin successful.

Make sure the Turnin is successful, otherwise we won't receive your submission! . If you want to make changes after you've turned in your homework, make the changes and run bundlePSA7 again. The program will warn you that a "previously turned-in file exists" and ask if "you wish to over-write this existing file". Respond in the affirmative by typing y and pressing the Enter key.

Getting your interview done INDIVIDUALLY

10% of your grade on this assignment will come from an interview you will have with one of the tutors during Open Lab Hours. You have 48 weekday hours after the electronic turnin deadline to get your interview done. The deadline for the interview for PSA7 is Thurs Feb 19th (theoretically at midnight, but actually by the end of the last tutor hour scheduled). Remember, the tutors may be busy after 4pm helping CSE8B students

You get an interview by going into B260 during a scheduled tutor hour. Find the tutor, ask them if you can interview for the 8A PSA. If they have others who are waiting for interviews, your name will go on the end of the list of people waiting. Interviews take about 5 minutes each. It is your responsibility to go in early enough that you can get your interview completed. If everyone waits until the last hour on Thurs, this will not work.

For the interview you will need to have a copy of your team's assignment in your account. If you are using your partner's account to submit the files, make sure you email them to yourself and save them under your account so that you have them available for the interview. The tutor will ask you to log in, change to the directory where your work is and then to follow their directions. They will ask you to run your program to show that it works, open files in Dr. Java (or your favorite editor), and ask you questions about HOW your code works. Additionally, they may question you as to how you would (theoretically) make small changes to the program to have it do something slightly different. You will not actually be required to change your code.

Learning to be able to explain your problem solving process and discuss code with another human being is a very important professional skill. We hope that this process will help you develop this skill.