Held: Monday, 16 September 2013

Back to Outline 09 - An Introduction to the GIMP. On to Outline 11 - A Design Perspective.

Summary

We continue our synthesis of algorithms and image making as we explore techniques for programming with the basic GIMP tools.

Related Pages

• Reading: Programming the GIMP Tools
• Lab : Programming the GIMP Tools
• EBoard (Source) (PDF)

Overview

• A new model of images making.
• Coding algorithms for drawing.
• Other useful techniques.
• Lab.

Administrivia

• Study break, tonight at 8pm.
• Grading stuff
  • I finally finished grading HW1. Sorry for the delay.
  • Our grader has graded HW2 and I'll be returning it and commenting on it.
  • I'll be returning Friday's quizzes. Some of you may want to chat with me.
  • I'll distribute the exam tomorrow.
• Not quite lab writeup (due Wednesday):
  • Document the rectangle procedure from the first lab on drawings.
  • Email to rebelsky@grinnell.edu, subject "CSC 151.02 Lab Writeup: Documentation"
• Reading for Tuesday: Design and Color
• EC Opportunities:
  • Convocation this Wednesday (see Sam's rant on the importance of convo in the outline for more details)
  • CS Extras Thursday @ 4:30: Kim Spasaro on Linguistics Programming
  • CS Table Friday (Pair programming)
  • Other?
• I also encourage you to attend any of the other Title IX talks/events.

Models of Images

• As we've seen in our early discussions, there are many ways to think about an image.
• In our first explorations with the GIMP, we looked at an imperative, tool-based model of drawing.
  • The model is imperative in that it consists of a sequence of commands (do this, then this, then this).
  • The model is tool-based in that almost all operations involve selecting a tool and then applying that tool.
• Over the next few weeks, we'll see a variety of other models.

Encoding Drawing Cmmands

• Because there are only a limited number of basic actions one can perform in GIMP, it is possible to represent each of these actions as a procedure.
• These procedures are parameterized in that you can modify how they work by providing different input values.
• Many of these procedures change the state of the system. When procedures change things (as opposed to computing new values), we tend to suffix their name with an exclamation point.
• For clarity, we tend to prefix the name of a procedure with the kind of value it works on. For example,
  • procedures that modify and create images begin with image-,
  • procedures that modify the global context begin with context-,
  • procedures that modify and create colors begin with color-.
• The primary model we use is to repeatedly select and then stroke or fill regions.
• We do not expect you to remember all of these procedure names.
  • One of the flaws of the current strategy for teaching 151 is that there are way too many procedures to remember.
• There is (or should be) a convenient reference menu in MediaScheme.
  • There is also a convenient reference section on the Web site.
• If there's something that you want documented, bug me.

Lab

• Work on the labthe lab.
• Be prepared to reflect on some of the questions contained therein.