CS 4 Computer Science Bootcamp
Summer 2018

Lab 6

You will be using the Python module cImage.py, which we studied in class. "Right-Click and Save" this module to a folder on your desktop. Also, I wrote several functions for you to use, which are all found in a single program file water.py. Save this file into the same folder.

I also have three images for you to experiment:

• leo1.gif: size 500x500
• kate.gif: size 500x500
• sun500.gif: size 500x500
• ucsb.gif: size 500x500

The module cImage.py comes (built-in) with the following image and pixel functions:

• im1 = FileImage("leo1.gif"): This function creates an abstract link to the image file "leo1.gif" and represents it in the program as "im1".
• im2 = EmptyImage(n,m): This function creates an empty image data structure, which is of size nxm.
• n = im1.getWidth(): This function returns the width (the number of columns) of the image "im1".
• m = im1.getHeight(): This function returns the height (the number of rows) of the image "im1".
• mywin = ImageWin("Test",n,m): This function creates a window of size nxm to draw images. The title of the window is "Test".
• im1.draw(mywin): This function draws the image "im1" inside the window "mywin" starting from the left-top corner. If the image is smaller than nxm, the rest of the window will be empty. If the image is larger, it will be clipped.

• Embed(x,y,k): This function places higher k bits of y into lower k bits of x, where x and y are 8-bit integers and k=1,2,3,4,5,6,7.
• Extract(x,k): This function returns y such that higher k bits of y comes from lower k bits of x, where x and y are 8-bit integers and k=1,2,3,4,5,6,7.

• MakeWaterMark(im1,im2,k): This function uses im2 as a watermark and places im2 into im1, such that the lower k bits of every color of every pixel of im1 comes from higher k bits of every color of every pixel of im2.
• ExtractWaterMark(im1,k): This function extracts the lower k bits of every color of every pixel of im1 and creates a new image im2, and places these bits as color values of every pixel in im2.

Lab Instructions

import os
os.chdir("/Users/koc/Desktop/abc")
from cImage import *