Unit 1- Digital Information ('21-'22)
You've been given a new cell phone with a 2 gigabyte data plan. You plan to use your phone for text messages, images, video, and music. Which of these categories are best compressed using lossless compression? Which of these categories are best compressed using lossy compression? Why?
- Images, video, and music are best compressed using lossy compression because you can lose data without the human eye or ear noticing much. - Text messages can best be compressed using lossless compression because you can reduce the number of bits needed without losing any information. (if you are taking away, for example, all the vowels, which would be lossy compression, it will be harder to know what the message means)
Why did we decide to send a message as a sequence of two options rather than modifying our devices to represent more options?
- Messages were sent as a binary question rather than a question with more answers because it is more complicated to make a device with many answers. - Combinations are hard to make infinate (and will run out). - Answers with numbers are easier to represent more states because they can be infinite (while seasons, hours of the day, etc. are finite)
Describe how the process of sampling, RGB pixels, and binary sequences work together to display a digital color image.
- Sampling is a method of converting analog into a digital image through binary sequences and RGB pixels are what shows up on our screen. - Those RGB pixels become the digital image you desire.
What are the similarities and differences between the binary and decimal systems?
- Similarities are both systems use the concept of place value, and in both systems, we can calculate each digit's value by multiplying the digit with the matching power of 2 and 10. - Difference are the decimal number systems uses 10 digits (0-9) and the binary systems uses 2 (0-1) digits.
Assume your friend just sent you 32 bits of pixel data (just the 0s and 1s for black and white pixels) that were encoded after sampling an image. State the two statements that are true:
1) The correct width and height must be input into the pixelation widget to produce the image. 2) Only 32 bits were used to represent the image, so large sample squares were used. The digital image may be very diffferent from the analog image.
Which statement about analog and digital images is true? 1) With advances in technology, digital images look exactly like the analog images they represent. 2) Sampling an analog image more frequently produces a digital image with a better representation. 3) Analog images come from data that is measured at regular intervals. 4) Digital images come from data that is measures continuously.
2) Sampling an analog image more frequently produces a digital image with a better representation.
The Internet Engineering Task Force (IETF) defines the protocols and standards for how the Internet works. The members of the IETF are:
A loosely organized collection of citizens and engineers who communicate mostly by email.
Protocol
A set of rules governing the exchange or transmission of data between devices.
ASCII
American Standard Code for Information Interchange
Which of the following would result in a better digital approximation of an analog black and white image? A) Increasing the size of each sample square, thus decreasing the number of samples taken. B) Decreasing the size of each sample square, thus increasing the number of samples taken. C) Using fewer bits to represent the image. D) Using decimal numbers to represent each pixel.
B) Decreasing the size of each sample square, thus increasing the number of samples taken.
How is a Creative Commons license different from a regular copyright?
Creative Commons is a way to easily share copyrighted work. When work is copyrighted, some intense protections are put on the work, but not everyone wants all of those protections to that degree. Plus, having a bunch of people go through all the copyrighted procedures to use your work wastes a lot of time and money for both parties. Creative Commons lets you still have control of your work, but also lets others use it as long as they abide by the certain rules you put in your creative commons. This saves both parties time and money, allows the original creator to not relinquish all control, and also lets others use their work.
Overflow Error
Error from attempting to represent a number that is too large
How would you explain a number system to someone who had never seen numbers before?
I would present the numbers with one digit with a symbol (like a shape) and then I would present the numbers with 2-digit numbers with 2 shapes
Each time we add another bit, what happens to the amount of numbers we can make?
It multiples by two (or raises to the power of 2)
Modern car odometers can record up to a million miles driven. What happens to the odometer reading when a car drives beyond its maximum reading?
Overflow error- the odometer cannot read any more than a million so all of the numbers will return to 0s.
What is an RFC?
Request For Comments
An author is preparing to send their book to a publisher as an email attachment. The file on their computer is 1000 bytes. When they attach the file to their email, it shows as 750 bytes. The author gets very upset because they are concerned that part of their book has been deleted by the email address.If you could talk to this author, how would you explain what is happening to their book?
The computer used lossless compression. No data is lost, and it's reversible. Say the author wrote a book about cats. She probably used the word cat a lot, so the computer just inserted a symbol wherever the word cat was to compress the data and make it smaller to send. When the publisher opens up the email attachment, the entire book will be there without any symbols.
What is the most important quality of lossless compression?
The data is transformed to usually make it smaller. It can always be re-constructed back to the original.
Heuristic
a problem solving approach (algorithm) to find a satisfactory solution where finding an optimal or exact solution is impractical or totally impossible
Lossless Compression
a process for reducing the number of bits needed to represent something without losing any information (this process is reversible)
Lossy Compression
a process of reducing the number of bits needed to represent something in which some information is lost or thrown away (non-reversible)
Abstraction
a simplified representation of something more complex (allows you to hide details to help you manage complexity, and easier to read/ understand)
When using bits to represent fractions of a number, can you create all possible fractions? Why or why not?
binary can precisely represent some fractional amounts from the decimal number system, but binary cannot precisely represent other fractional values from the decimal number system
Creative Commons
collection of public copyright licenses that enable the free distribution of another with copy righted work (used when an author wants to give people the right to share, build upon and use their work)
Digital Data
data that changes discreetly through a finite set of possible values
Metadata
data that describes other data (ex. the size of a picture or image)
Analog Data
data with values that change continuously, or smoothly, over time (ex. music, colors of a painting, or position of a sprinter during a race)
Round off Error
error from attempting to represent a number that is too precise (the value is rounded)
Screen Density
how many pixels are in a given area (more pixels/ sharper image)
Open Access
online research output free of restrictions to access and use
Sampling
process of creating a digital representation of analog data by measuring the analog data at regular intervals
Open Source
programs that are made freely available and may be redistributed and modified
RGB
the color model using varying intensities of red, green, and blue light added together to make a broad spectrum of colors
Pixel (picture element)
tiny square or dot that contains a single point of color of a larger image (fundamental unit of a digital image)
