1. Digital Media Lecture 2: SemesterOverview Georgia Gwinnett College School of Science and Technology Dr. Jim Rowan

2. Sampling The process used to convert continuous phenomena in the real world to discrete numbers stored on a computer But… this process makes an “alias” of the original; it’s an approximation of the original that does have faults These negative side effedts are called artifacts

3. Sampling artifact examples: With audio, one artifact is quantization hiss With video, one artifact is retrograde motion; wheels look to turn backwards http://wiki.ggc.edu/images/3/35/RetrogradeGMCarcadiaBroadbandHigh.mov http://wiki.ggc.edu/images/8/85/JrowanSpring2012CroppedRetrogradeMotionClip.mov Moving images: Film With images one artifact is posterization http://wiki.ggc.edu/wiki/BitmappedImageDitheringPosterizationjrowanSummer2012 Images as piles of numbers: Bitmapped images: Dithering and posterization

4. Some sampling artifact causes One cause of quantization hiss is undersampling –Not storing enough different levels for each sample taken One cause of retrograde motion is undersampling –Taking too few images per second (too few samples) One cause of posterization is not having enough quantization levels –Not storing enough different levels for each of the samples taken

5. Sampling artifacts More on this later in the class

6. How do you store sound? Collect samples of the sound and play them back Store it as numeric codes (midi) and regenerated it from those codes But we will only deal with collecting samples in this class

7. How do you store images? There are two techniques we will discuss in this class Bitmapped images –Store the image as a collection of spots of light known as pixels Vector graphics –Store the image as a mathematical description of the objects in the image

8. Bitmapped image A collection of spots (pixels) of light

9. Vector graphics A mathematical description of the objects in the scene This image could be described like this: (x1,y1) (x2,y2) (255,0,0) (x3,y3) (x4,y4) (0,0,255)

10. Why are there two ways to describe images? Bitmapped images –The size of the file depends on how many pixels there are in the image –The content of the image does not affect the file’s size –But…. they do not scale well

11. Why are there two ways to describe images? Vector graphics –The size of the file depends on how many objects there are in the image –So… the content of the image does affect the file’s size –But…. they are scalable

12. A brief look at the Internet –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues

13. A brief look at the Internet –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues

14. A brief look at the Internet: How to request stuff –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues Uniform Resource Locator (URL) http://www.amazon.com/newStuff/index.html Has 3 parts Protocol HTTP:// FTP:// SMTP:// Domain name Ends in.edu.com.gov.org Directory structure and the requested page /newStuff/index.html

15. A brief look at the Internet: How to request stuff –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues Uniform Resource Locator (URL) http://www.amazon.com/newStuff/index.html Has 3 parts Protocol HTTP:// FTP:// SMTP:// Domain name Ends in.edu.com.gov.org Directory structure and the requested page /newStuff/index.html

16. A brief look at the Internet: How to request stuff –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues Uniform Resource Locator (URL) http://www.amazon.com/newStuff/index.html Has 3 parts Protocol HTTP:// FTP:// SMTP:// Domain name Ends in.edu.com.gov.org Directory structure and the requested page /newStuff/index.html

17. A brief look at the Internet –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues

18. A brief look at the Internet –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues

19. A brief look at the Internet –http://wiki.ggc.edu/wiki/NetworkingIssueshttp://wiki.ggc.edu/wiki/NetworkingIssues –Let’s get started: Networking issues

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