INQ 241A

Lab 13: Images

Practice Problem 1

Write a function omit_letters(a_phrase, omitted_letters), which takes a string as a parameter. Your function should list all of the characters out of a_phrase, each on their own line. However, your program should only print the letters not included in the omitted letters string.

Example

>>> omit_letters("INQ 241A", "241")
I
N
Q

A
>>> omit_letters("Trexler", "e")
T
r
x
l
r

Hint

Practice Problem 2

Write a function perfect_squares(maximum_sqrt), which takes an integer as a parameter. This function should print all of the perfect squares whose square root is less than maximum_sqrt.

Example

>>> perfect_squares(10)
0
1
4
9
16
25
36
49
64
81
>>> perfect_squares(5)
0
1
4
9
16

Hint

Better Hair Replacement

In a file called hair_color.py, write a function called change_hair_to_red(picture). This function should take 1 parameters: the picture you are going to modify. Your function should use what you learned today in class to make the changing of the hair color better.

Example

Before

After

Hint

Like previously, you want to iterate over all of the pixels of your image. To do this, you need to use a for loop over the pixels of the image. You can get a listing of the pixels using the getPixels(a_picture) function.

getColor(a_pixel) will give you the color of a pixel from the image.

You can use the distance function to determine if two pixels have a color that is similar. If a pixel's color is stored in a variable called pixel_color, distance(hair_color, pixel_color) will return a floating point value representing how far apart the colors are.

The setColor(pixel, color_value) function can be used to set a specific pixel to a specific color.

Use the explore tool to determine a "box" that you want to change the hair color in. It doesn't have to be perfect, but you should try to make it so that you don't have any areas with a similar color to the hair are inside of the box.

Use the if statements to only allow for pixels that are inside of the box. If the box has coordinates $x_1, y_1, x_2, y_2$ , then your condition can check to see $if(x_1 < x < x_2 \mbox{ and } y_1 < y < y_2)$ .