CSC151.02 2015S, Class 22: Images as Functions from Position to Colors
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* New partners (who will also serve as homework partners)!
    * Separate cards for those who do and do not want a HW partner

_Overview_

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

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

### Admin

* Quiz Friday!  Conditionals, higher-order procedures, and let.
* Review sessions Thursday 9:00 a.m., 1:15 p.m., and 8:00 p.m.
* Office hours Friday at 10:00 a.m.  Also available informally after
  class today.
    * <http://rebelsky.youcanbook.me>
    * I'll see what I can do about freeing up Thursday hours.
    * If you don't see me in my office, check my lab (right next door).
* Our graders say
    * "Please limit your lines to eighty characters!"
    * "Remember that we are going to copy and paste your work into
      DrRacket.  So don't add things after you copy and paste from
      DrRacket."
* Your peers say   
    * "It's really helpful to save your work from the interactions pane."
    * "Copy-paste-comment"
* I plan to distribute an answer key to HW 5 tonight (or when the last
  homework comes in).

### Upcoming Work

* [Homework 6](../assignments/assignment.06.html).
    * Due Tuesday at 10:30 p.m.
* Exam 2 to be assigned in a week.
* Lab writeup for today: Problem 3,
  <http://bit.ly/151-2015S-lab22>
* Reading for Friday
    * [Building Data Structures with Heterogeneous Lists](../readings/heterogeneous-lists-reading.html)

### Extra Credit Opportunities

#### Academic 

* Pioneer Diversity Council Diversity Dialogue, 8:30 p.m. Thursday the 26th, 
  Main Quad "Academic Athletes and Academic Students".  
* CS Table Friday - Art, CS, and Artificial Intelligence.

#### Peer Support (Afternoon Section)

* Indoor Track this Saturday - GC Pride!

### Other Good Things

* Neverland Players this weekend.
* Jazz band Thursday night.
* Orchestra a week from Saturday.

### Questions

Lab/Debrief
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Is it okay if the diagonal blend is close but not exact?

* Yes.  Once we save as a PNG, we lose some resoultion.

How can I check my pixel values for a blend?

        > (define blend (horiz-black-blue-blend 100 100))
        > (map (lambda (col) (irgb->rgb-list (image-get-pixel blend col 50)))
               (iota 100))