CSC151.01 2015S, Class 14: Transforming Colors
==============================================

* New partners!

_Overview_

* Preliminaries.
    * Admin.
    * Upcoming Work.
    * Extra Credit.
    * Questions.
* Lab.

Preliminaries
-------------

### Admin

* Mentor session tomorrow at 8:00 p.m.
* Review sessions tomorrow at 9:00 a.m. and 1:15 p.m.
* No quiz Friday!

### Upcoming Work

* [Exam 1](../assignments/exam.01.html).
    * Exam due in electronic form due last night at 10:30 p.m. (free extension
      until tonight at 10:30 p.m.).
    * Exam due in printed form TODAY (free extension until Thursday
      at review time).
    * Required epilogue due TONIGHT at 10:30 p.m. (free extension until
      TONIGHT at 11:00 p.m.)
* No lab writeup for today (no matter what it currently says online)
* Reading for Friday
    * [Boolean Values and Conditionals](../readings/boolean-reading.html)
* HW4 due next Tuesday (to be distributed later tonight): Color and
  Image transformations
    * You will write color transformations, like you are doing in class
      today.
    * You will learn how to apply them to images.
    * Your partner is your lab partner from today's class

### Extra Credit Opportunities

#### Academic 

* Diversity Dialogues, February 19: 8:30 p.m. in Main Quad, sponsored by
  Pioneer Diversity Council.  ("Indoor Quidditch Matches"?)
* TEDx Grinnell, February 21

#### Peer Support (Afternoon Section)

* Swimming, Conference Championships, February 13-15, The Osgood
* Track and Field, Saturday, the "No one has donated the requisite
  $1mil to name this space" field house.
* Men's Basketball vs. Knox, next Wednesday at 7:30 p.m., New Darby
* Noteworthy fundraiser

## Recommended, But no EC

* 2 <3 GC day next Wednesday.

### Questions

Lab
---

Remember: 

* (image-show canvas) and (image-show canvas) will create two windows on 
  the same images, not two images.
* GIMP hates to show updates, so you may need to force it to.

Why use

    (image-set-pixel! canvas 0 0 
                      (irgb-darker (image-get-pixel canvas 0 0)))

rather than

    (image-transform-pixel! canvas 0 0 irgb-darker)

Because we can shift pixels

    (image-set-pixel! canvas 2 3 
                      (irgb-darker (image-get-pixel canvas 3 2)))

Or change images

    (image-set-pixel! canvas 2 3 
                      (irgb-darker (image-get-pixel savnac 3 2)))

Why are

    (irgb-complement (irgb-darker fave1))

and

    (irgb-darker (irgb-complement fave1))

different?

*