Held: Friday, 25 September 2015

Back to Outline 16 - Homogeneous Lists: Making and Manipulating Groups of Drawings . On to Outline 18 - Conditionals.

Summary

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

Related Pages

• Reading: The GNU Image Manipulation Program
• Reading: Programming the GIMP Tools
• Lab: Scripting the GIMP Tools
• EBoard 17 (Source 17)

Overview

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

Administrivia

• Continue partners.
• Remember; You can be on the CS mailing list and here about all of our events (and internships, and random comments from students and faculty, and SEPC study breaks, and ...).
• Moment of silence.
• Friday PSA.

Upcoming Work

• Readings for Monday: Conditionals
• HW 4 is now ready. We'll look at it quickly.
• No lab writeup today!

Extra Credit Opportunities

Academic

• Any visit to the current show in the Faulconer gallery.
• EE's show in Smith
• CS Table next week: YouTube Content Identification.

Too Much Text About CS Table

This week we'll be talking about Youtube and its efforts to enforce the rights of copyright holders with its ContentID system. Early this month, a federal appeals court in San Francisco "affirmed that copyright holders must consider whether a use of material is fair before sending a takedown notice".

This ruling is the latest development in an on-going battle between copyright holders, Youtube content creators who use the copyright holders content, and Youtube's system---ContentID---to help automatically enforce copyright in its system.

To understand the situation, please read this Gamasutra article---a primer on ContentID for Youtube content creators:

http://gamasutra.com/blogs/StephenMcArthur/20140624/219589/How_to_Beat_a_YouTube_ContentID_Copyright_Claim__What_every_Gamer_and_MCN_Should_Know.php

Then catch up on the background of this latest court ruling:

https://www.eff.org/press/releases/important-win-fair-use-dancing-baby-lawsuit

https://www.eff.org/cases/lenz-v-universal

If you are interested in how Google actually checks for copyright infringement of millions of videos, this algorithmic technique is called fingerprinting. Here is a short technical paper from Google on the approach that ContentID takes (based on finite-state transducers versus traditional hashing methods):

http://cs.nyu.edu/~eugenew/publications/icassp07.pdf

Peer Support

• Pals of PALS, pals@grinnell.edu, normally Saturday at 7:45 am (breakfast included), Sunday at 4:45, and Mondays at 4:45. Requires sign up in advance. Fundraising activity Saturday at 10:30 at 824 High Street.
• Pun Club, Saturdays, 4pm, Way over Younker.
• Singers concert on Family weekend! Sept. 26, 2pm., Sebring-Lewis
• Orchestra concert on Family weekend! Sept. 26, 2pm., Sebring-Lewis
• Eid dinner tonight. If it stretches your finances to pay for the ticket, let me know and I'll pay.

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.