Computer science test one

What is the most important quality of lossless compression? a) The data is transformed to usually make it smaller. It can always be re-constructed back to the original. b) The data is transformed to always make it smaller. It can always be re-constructed back to the original. c) The data is transformed to usually make it smaller. It cannot always be re-constructed back to the original. d) The data is transformed to always make it smaller. It cannot always be re-constructed back to the original.

.a

What number symbolizes black/off

0

What number symbolizes white/on

1

Digital Image layer of abstraction

Displays a digital approximate based on a sampling of an analog image

Sampling

A process for creating a digital representation of analog data by measuring the analog data at regular intervals called samples

Selection

Allows for a "decision" in code

Iteration

Allows the repeating of one (or more) program statements until a condition is met

All "descions" are what?

Binary (yes/no)

Example of procedural abstraction

Clean the kitchen, turning on your phone

abbreviations and symbols is a form of what

Compression

procedural abstraction

Creating a procedure that holds a bundle of instructions

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.

Digital Data

Data that changes discreetly through a finite space

Analog Data

Data with values that change continuously, or smoothly, over time.

Layers of Anstraction

Digital Image layer, sampling layer, pixel layer, binary layer

In coding a computer will run...

Each line from top to bottom in order

Pixel Layer of abstraction

Each pixel is represented by levels of red, green, and blue ligjt

As a reminder, in the warm-up we saw the this scenario: Imagine you were using some of our pixelation tools to create an image and you posted it online for your friends to see - but, a week later you find out someone took that image and put it on a T-shirt that they're selling for $10 each. Now that we understand Copyright, what would need to change in order for the scenario from the warm-up to be okay?

I would have to create a creative commons license that allows people to use my work and sell items with my work on them.

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. Like in the voting section of the PowerPoint, the images were compressed, but it wasn't very drastic. Text messages can best be compressed using lossless compression because you can reduce the number of bits needed without losing any information. In a text, using abbreviations and symbols is ok because most people know what they mean. But 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.

What are the two types of compression

Lossy and lossless

Abstraction

Making the complex simple or ignoring details that are not needed

Example of analog data

Music, colors, position

Lossless Compression

No data is lost so it can be decompressed back into the exact original, A process for reducing the number of bits needed to represent something without losing information, reversible

Data Abstraction

Numeric data representation to give machines instructions from text/symbols

Example of data abstraction

QR code, hyperlink, barcode

What is creative Commons

Refined copyright so it works better for you

Sampling Layer of abstraction

Samples of equal size are read from the analog image and assigned to pixels

What are the typea of algorithim?

Sequencing, selection, or Iteration

What things use lossy compression

Sounds, images, video

Sequencing

Steps in an ordered process

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.

Algorithim

a set of steps used to complete a specific task

Binary layer of abstraction

The red green and blue values are represented using sequence of binary numbers and sent out via electrical signals

"The binary pattern 01000001 represents the number 65." Write a brief response explaining whether you believe this statement is always true. Explain your reasoning.

This statement is sometimes true. The binary pattern 0100 0001 can represent 65, but it can also represent the character A.

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?

When a car drives beyond its maximum reading, it doesn't still show the distance driven. Instead, it resets to 0.

Lossy compression

When some info is thrown away to make it smaller, A process for reducing the number of bits needed to represent some thing in which some information is lost or thrown away, not reversible

When is lossless compression useful

When the accuracy of the original item is most important

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

Decimal number

base 10 (0-9)

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. Choose the two statements that are true: a) The 32 bits of pixel data is enough to produce the image using the widget. Nothing else is needed. b) The digital image would be an exact copy of the analog image. c) The correct width and height must be input into the pixelation widget to produce the image. d) The fact that only 32 bits were used to represent the image indicates relatively large sample squares were used. The digital image may vary from the analog image significantly.

c and d

When using bits to represent fractions of a number, can you create all possible fractions? Why or why not?

no. You would need an infinite number of place values and you could never get to the smallest fraction, it can always get smaller.

Open Access

online research outputs that are free of restrictions tn access and use

Open Source

programs that are made freely available and may be redistributed and modified