Lab 2: Rose-Colored Glasses or Jaded

Michael Stewart

Colors as points in 3D color space

• Today we will continue to take advantage of the distance between two colors as representing those colors’ similarity.

• This is facilitated by our encoding of color.• One way to view this encoding is :• http://en.wikipedia.org/wiki/

File:RGB_color_solid_cube.png

New JES methods

• pixel.getRed…• color.getRed…• setColor(pixel, newColor)• distance(color1, color2)

• dir

Driver Function

• Sometimes when programming, you may want to test many different functions

• Or you may want to test a function that requires several arguments

• Writing one function which makes these tedious calls for you can be useful

Conditionals and Branching

http://xkcd.com/210/

Conditionals and Branching (cont’d.)

• So far our code has been rather declarative• However we can write recipes that perform

differently in different circumstances.• This is usually called “branching” or

“conditionals”

Conditionals and Branching (cont’d.)

• The simplest kind of branch statement is the “if” statement.

• In this example, the function “doSomething” will only be called sometimes.

if somethingIsTrue:

doSomething()

Boolean

• In normal numerical arithmetic, you use numerical operators (+, -, *, /) and multiple numbers, to produce a numerical result.

• In BOOLEAN arithmetic, you use boolean operators (==, <, >, not, and, or, etc.), and multiple boolean/numerical values(True, False), to produce a boolean result.

Boolean (cont’d.)

• Let’s try some in the command window:• 1 > 2• 1==1• True and False• Not True

A B A and B A or B

True True True True

True False False True

False True False True

False False False False

Lab Assignment

• Download the skeleton for the lab from today’s page

• Start with an image like this

Lab Assignment (cont’d.)

• First, tint the image to a desired color, like this:

Lab Assignment (cont’d).• Swap Roles with your partner.• Now, change the color of a certain range of

colors. So using the same starting point as tint, produce this:

Lab Assignment (cont’d.)

What’s the difference?!

Lab Assignment (cont’d.)

In the first picture, you’re making every

pixel closer to the target color.

In the second, you only change pixels of similar color to a color of your

choice.

Lab Assignment (cont’d.)

• Submit your work to the Lab 2 Moodle assignment