The purpose of this project is to make a program that processes a list defining a collage and builds the resulting image. The collage list information can specify if the program should apply an effect and/or an alpha blend to each image.

Tasks

For this assignment you're going to create a couple of new functions. One, buildCollage, should go in your collage.py file and will process the collage list information and build the output image. The other, putPixmapNoBlue, should go in your filter.py file and will be identical to putPixmap, except that it will not transfer blue screen pixels into the destination image.

1. In your collage.py file, create a function buildCollage, as given below. Each comment is a line of python code in the final function. The indentation of the comments should match the code.

   def buildCollage( clist ):
       # assign to (rows, cols) the result of calling getImageSize with clist
       # assign to dst the result of calling graphics.Pixmap with cols and rows
       # for each item in clist
           # assign to filename the first element in item 
           # assign to x0 the second element in item
           # assign to y0 the third element in item
           # assign to operator the fourth element in item
           # assign to alpha the fifth element in item
   	# assign to noBlue the sixth element in item
           # assign to src the last element in item (index -1)
   
           # use a set of if/elif statements to apply the correct
           # operator to the image (this is several lines of code)
   
           # call putPixmap to put src into dst at location x0, y0 with blend alpha
   
       # return dst
   

   You can use testbuildcollage.py to test your buildCollage function. The test function assumes that your build collage knows what to do with the operator strings 'rbswap' and 'original', as we went over in lab.

2. In your filter.py file, create a function putPixmapNoBlue that has the same arguments and does the same thing as putPixmap, but does not copy the src pixel into the destination image if the src pixel is part of the blue screen.
3. Edit your buildCollage program so that it uses the sixth element in the collage information list, stored in the noBlue variable, to determine whether to call putPixmap or putPixmapNoBlue as the last step in the main for loop.
4. Make a new python file (e.g. mycollage.py) that contains a single main function. Be sure to put a call to the main function behind a test on __name__.

   if __name__ == "__main__":
       main()
   

   The main function should create a collage information list, call readImages, call buildCollage, then write the image to a file. You can use the testbuildcollage.py file as an example. Your collage should use at least four different source images.

   The collage should include at least five different sub-images. Some of these can be copies of one of the source images with different effects. The collage should use at least 3 effects, at least one alpha blend, and at least one blue-screen image where the blue pixels are not copied into the collage.

   Required image 1 is your first collage.

5. Make a new python file, coverphoto.py, that takes in at least one image filename from the command line. It should build a collage appropriate for a Facebook cover photo and write it out to a file.

   The collage should be about three times as wide as it is tall and have at least three sub-images. You can control the height and width of the collage by appropriate selection and placement of your images, or you can fix the relative height and width and change putPixmap to safetly handle images that go outside the image boundaries. You can choose random effects for the three images or pick specific effects. The collage should use at least two effects.

   Required image 2 is your cover photo collage.

Extensions

• Create some new image effects you didn't implement in the last lab.
• Make some additional programs that generate collages with specific geometric arrangements and that take their list of image files from the command line.
• Add additional options to the collage information list, like whether to mirror the image or not, in addition to the other options.
• Create a collage dynamically based on how many images are given on the command line.
• Figure out how to call the proper effect function on each image without using an if/elif control structure. (Ok, this is kind of esoteric, but it's a cool feature of python.)
• Uber-extension: put the collage information in a text file. Have your program read the text file (given as a command-line argument), parse the information, and build the collage.

Writeup and Hand-In

Before handing in your code, double check that it is well-styled:

• All variable names and function names use either camelCase or snake_case.
• All files and functions have docstrings.
• Comments are added to explain complicated code blocks.
• All variable and function names are appropriately descriptive.
• Functions are defined before any other code is added at the top level of each file.
• In a file with any functions defined, top level code is wrapped so that it won't execute if that file is imported by another.

Make a new wiki page for your assignment. Put the label cs151s14project5 on the page. Each of you needs to make your own writeup.

In addition to making the wiki page writeup, put the python files you wrote on the Academics server in your private handin directory.

Colby Wiki

In general, your writeup should follow the outline below.

• A brief summary of the task, in your own words. This should be no more than a few sentences. Give the reader context and identify the key purpose of the assignment.
• A description of your solution to the tasks, including any images you created. (Make sure your images are appropriately sized to fit onto the wiki page.) This should be a description of the form and functionality of your final code. You may want to incorporate code snippets in your description to point out relevant features. Note any unique computational solutions you developed.
• A description of any extensions you undertook, including images demonstrating those extensions. If you added any modules, functions, or other design components, note their structure and the algorithms you used.
• A brief description (1-3 sentences) of what you learned.
• A list of people you worked with, including students who took the course in previous semesters, TAs, and professors. Include in this list anyone whose code you may have seen. If you didn't work with anyone, please say so.
• Don't forget to label your writeup so that it is easy for others to find. For this lab, use cs151s14project5