In this prelab you will formulate some of the ideas necessary to complete Lab 04. Please type up your solutions, and hand in a paper copy before the beginning of lecture on Wednesday. Remember, no late prelabs allowed!
Read about one of the first Computer Scientists, Ava Lovelace, who predated computers by a century.
def main() : blarg(5) blorf(3) def blarg(x) : print(x*x) print(x) def blorf(y) : blarg(y+1) print(y) blarg(y-1) main()
3. What is the output of the following program?
def main() : x = 2, y = 7 print(x, y, end="") x = blunk(x, y) print(x, y, end="") def blunk(y, x) : print(x, y, end="") y = y * y x = x//2 print(x, y, end="") return x*y main()
5. Write a chunk of code with the following behavior. First, it should prompt the user to enter four numbers (x1, y1, x2, y2) separated by commas. It should then compute and print the slope of the line that joins the points (x1,y1) and (x2,y2). Your code should handle at least three possible exceptions.
In the lab proper, you'll be using graphical primitives (rectangles, circles, lines, etc.) to create an image of your own choosing.
In this portion of the lab you'll create a nifty program that reads in an image and does a sequence of modifications to that image, as specified by the user. Things like negating the image, blurring it, changing the contrast, etc.
Describe the Problem:
|Your program should prompt the user to enter the filename of an image to edit. It should then repeatedly prompt them for filters to apply, and show the cumulative effect of these filters on the specified image.|
Understand the Problem:
Consider the image of crayons above. There are numerous transformations we might apply to this image. For the lab, you'll be creating a program capable of the following operations:
Examples of these operations are given below.
Design an Algorithm:
|Your program should begin by printing a welcome to the user, informing them just how fortunate they are to have stumbled upon your very own image editor. You should then prompt the user in the console to pick a file to load in. As will be standard from here on out, you'll want to be robust against bad user input, so if the user enters something that isn't a valid file and an exception is thrown, you can catch it and prompt them again for a file.
Once you have an image loaded, display it. Then use a while loop to repeatedly print a table of possible operations, prompt the user to select one of these operations to apply to their image, apply the selected operation (create a distinct function for each operation), and display the resulting image. Thus, the user might choose to reflect the image, then increase the contrast (of the now reflected image), and then blur (the now reflected and contrasty image). At each step, the user should be able to see the resulting image. Again, be sure to handle bad input from the user.
Of course, this still leaves out the details of each operation, for which you will want to write pseudocode before you start writing functions. Details for some of these operations are given below.
- For some of these operations, you may want to create a new image rather than by simply modifying the existing image. You may assume you can generate a copy of an image.
- You can not change the position of a pixel. You can, however, read the r, g and b values for any pixel, and you can set the r, g and b values of any pixel.
Sample answer: loop over x values from 0 to W - 1 inclusive (You can assume W is the width) loop over y values from 0 to H - 1 inclusive (You can assume H is the height) change the red value of the pixel at (x,y) to 07. Negate the image.
8. Convert the image to grayscale.
9. Flip the image.
10. Scroll the image to the right by d pixels.
If you followed the Honor Code in this assignment, write the following sentence attesting to the fact at the top of your homework.
I affirm that I have adhered to the Honor Code in this assignment.