CSC 151.01, Class 07: Transforming Images

Overview

• Preliminaries
  • Notes and news
  • Upcoming work
  • Extra credit
  • Questions
• Sectioning
• Anonymous transformations
• Lab
• Debrief (?)

News / Etc.

• New partners!
  • Grab a card from the table
  • Identify which computer you should be on
  • Put the card in the jar
  • Go to the computer
  • If no one is there: Log in; bring up DrRacket, Gimp, and Firefox; Load the current lab in Firefox.
  • If someone is there: Introduce yourselves.
• Please don’t leave your quizzes in the room. If you don’t want them, dispose of them appropriately.
• Still working on grading HW1. Sorry.
• You should have received a message from Stacy Turley requesting note-taking for this class. It looks like many of you are taking very nice notes (better than I do). I hope that you will respond to the request.
  • Everyone: If you’d like to see more in the eboards, tell me what I’m missing (or tell someone to tell me).
• I’m supposed to remind you that Friday is the add/drop deadline.
• Reminder: The lab writeups go to csc151-01-grader@grinnell.edu.
• Quiz Friday!
  • Numbers and numeric operations.
  • RGB colors and color operations.
  • Color transformations.
  • The compose operation.
  • Scheme order of evaluation.
  • The questions you should ask about types.

Reminders

• We have tutors available Sunday through Thursday evening from 7-10 p.m. in Science 3813/15.
• Starting this week, we will have mentor sessions on Wednesday and Thursday evenings from 8:00-9:00 p.m. in the CS Commons. Wednesdays will be more Q&A, Thursdays will include sample quizzes.
• I run review sessions on Thursdays at 9am in this room.
• We have individual tutors available for those who take advantage of the above and find that it’s not enough.

Upcoming Work

• Assignment 3. Due next Tuesday!
• Reading: Writing your own procedures.
• Lab writeup: Exercise ???. Due Friday before class.

Extra credit (Academic/Artistic)

• Thursday extras, Thursday, 4:15 p.m., Science 3821: LaTeX.
• CS Table next Tuesday.

Extra credit (Misc)

• Any one of the activities relating to last Friday’s executive order.
  • See VP Connor’s email
  • Thursday at 7pm in Saints Rest

Extra credit (Peer)

• Swimming and Diving meet 1pm on Saturday.
• Ritalin Test Squad Improv Troupe is looking for new members and will be holding try outs this weekend. Auditions will be on Saturday Feb 4th, 1-3 pm in The Wall (Bucksbaum 152).

Good things to do

• Care for the people around you.
• More of the activities relating to last Friday’s executive order.
• Divest rally Friday at 3pm in ARH 302.

Questions

Can I ask a long question?

Yes.

What isn’t undoable?

Usually, darkening for already dark colors and lightening for already light light. Lighten sends. 250 -> 255, 255 -> 255, 242 -> 255

Are you really going to ask us to regurgitate the four questions you listed in class?

Maybe.

Why didn’t anyone laugh when you wrote regurgitate?

The Narrator wasn’t paying attention.

Sectioning

• We regularly want/need to write our own procedures.
• We will develop a reportoire (sp?) of different ways to write procedures.
• You can come up with a new name for an existing procedure. (define plus +).
• You can combine two existing one-parameter procedures with compose.
• You can fill in some parameters of a multi-parameter procedure with section. (define add2 (section + <> 2))
• We will look at a more general way of defining procedures on Friday.

Why do we call it sectioning?

• Because we fill in one “section” of the procedure call.

Lab

• Note: We can think of images as having multiple “names”. There’s the file name for the file used to store the image. But GIMP and DrRacket want to work with loaded images. So we use those names after doing the image-load.
• For the ugly prof-pic thing, use “/home/rebelsky/Desktop/kington.jpg”
• Note: You can’t put a section within a section. Hint: Use compose instead.

Writeup

Write up exercise 4 from the lab on transforming RGB images.

Send your solution to csc151-01-grader@grinnell.edu.

Title your email CSC 151.01 Writeup for Class 7 (YOUR NAMES).

The body of your message should indicate which answers, if any, you got wrong, and why, and then your answer to part c.

Debrief