UNIT 02 - Digital Information
EXPECTATIONS: Before we start this unit you should be comfortable with the following:

LEARNING GOALS -- At the conclusion of this unit, I will be able to :

      1. demonstrate how images and other complex information are represented in a computer

      2. explain how we reduce the size of digital information and the tradeoffs that are involved

      3. show why there are so many different formats for representing the same kind of information

      4. collaborate with a peer to find a solution to a text compression problem using the Text Compression Widget (lossless compression scheme).

      5. explain why the optimal amount of compression is impossible or “hard” to identify

      6. explain some factors that make compression challenging

      7. develop a strategy (heuristic algorithm) for compressing text

      8. describe the purpose and rationale for lossless compression

      9. explain how images are encoded with pixel data

      10. describe a pixel as an element of a digital image.

      11. encode a B&W image in binary representing both the pixel data (intensity) and metadata (width, height).

      12. create the necessary metadata to represent the width and height of a digital image, using a computational tool

      13. explain why image width and height are metadata for a digital image.

      14. use the Pixelation Tool to encode small color images with varying bits-per-pixel settings

      15. explain the color encoding scheme for digital images.

      16. use the Pixelation Tool to encode an image of the student’s design.

      17. explain the benefits of using hexadecimal numbers for representing long streams of bits.

      18. explain the difference between lossy and lossless compression.

      19. explain the relative benefits or drawbacks of different file formats, particularly in terms of how they compress information

      20. identify reliable sources of information when doing research

      21. explain the difference between open source and licensed software

      22. identify reliable sources of information when doing research

      23. synthesize information taken from multiple online sources

      24. create an artifact (video, image, slide, poster, etc.) to communicate information about a computing topic


Term Description
Heuristic a problem solving approach (algorithm) to find a satisfactory solution where finding an optimal or exact solution is impractical or impossibl
Hexadecimal A base-16 number system that uses sixteen distinct symbols 0-9 and A-F to represent numbers from 0 to 15
Image a type of data used for graphics or pictures
Lossless Compression a data compression algorithm that allows the original data to be perfectly reconstructed from the compressed data
Lossy Compression  (or irreversible compression) a data compression method that uses inexact approximations, discarding some data to represent the content. Most commonly seen in image formats like .jpg
Metadata data that describes other data. For example, a digital image my include metadata that describe the size of the image, number of colors, or resolution
Pixel short for "picture element", the fundamental unit of a digital image, typically a tiny square or dot that contains a single point of color of a larger image
RGB  the RGB color model uses varying intensities of (R)ed, (G)reen, and (B)lue light are added together in to reproduce a broad array of colors

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