APCS Unit 1: Digital Information

What are some examples of open source?

-Mozilla Firefox -Linux -VLC media player

What are some examples of lossy compression?

-Mp3 -Gif -Jpeg -LOL instead of "laugh out loud"

What are the characteristics of sampling?

-allows us to convert an analog piece of information into digital -we can choose how often we sample -more sampling=more accurate result -some images/sounds need more or less sampling

Lossy Compression

A process for reducing the number of bits needed to represent something in which some information is lost or thrown away. This process is not reversible.

Which of the following best describes how computing devices represent information? A) A computer represents information as bits which contain 8 bytes. B) A computer represents data as bits which is either a 0 or a 1. C) A computer represents data as a byte which is either a 0 or a 1. D) A computer will either represent information as bits or bytes but not both.

B

John is sending a large image file to a friend as part of a shared classroom project. Which of the following is most likely true if John opts to compress the image before sending it? A) The image will have been converted into analog form. B) The image can no longer be represented using bits. C) The image will require fewer bits in order to be represented. D) The image will require more pixels to display on the screen.

C

When visiting a museum Liam takes a photo of a painting with a smartphone which stores the photo as an image file. Which of the following best describes the difference between the painting itself and the photo of the painting stored on the smartphone? A) The photo is a digital representation of the analog painting. B) Sampling can be used to determine whether the analog image is an accurate representation of the painting. C) The phone can represent the photo in either digital or analog formats depending on the sampling technique that is used. D) Both the painting and the photo are analog.

C

Which of the following binary numbers is the largest? A) 10111111 B) 01111111 C)11000000 D)00000001

C

Which of the following is NOT true of how computers represent complex information? A) Common abstractions that are represented by computing devices include numbers, characters, and color. B) Depending on context the same sequence of bits may represent different types of information. C) Abstraction helps represent complex information by surfacing complexity that might otherwise be hidden. D) Computing devices use patterns of bits to represent complex information.

C

Which of the following is true of how computers represent numbers? A) Using a fixed but large number of bits, for example 128, eliminates the possibility of overflow errors. B) With a large but fixed number of bits, it is possible to eliminate either round-off errors or overflow errors, but not both. C) With a fixed number of bits some numbers are too large to represent in a computer which will lead to overflow errors. D) Using a fixed but large number of bits can eliminate the possibility of round off errors when representing numbers in binary.

C

Which of the following is true of lossy and lossless compression algorithms? A) Lossless compression algorithms only allow for an approximate reconstruction of the original data. B) Lossless compression algorithms are only used to compress text data. C) Lossy compression algorithms are used when perfect reconstruction of the data is important. D) Lossy compression algorithms are typically better than lossless compression algorithms at reducing the number of bits needed to represent a piece of data.

D

What type of data are these examples of? -music -colors of a painting -position of a sprinter during a race

analog data

When is sampling needed?

Sampling is used when converting from analog data to digital data.

Creative Commons

a collection of public copyright licenses that enable the free distribution of an otherwise copyrighted work, used when an author wants to give people the right to share, use, and build upon a work that they have created

Bit

a contraction of "Binary Digit;" the single unit of information in a computer, typically represented as a 0 or 1

Sampling

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

Data Compression

a process for reducing the number of bits needed to represent a piece of information

Digital Data

data that changes discreetly through a finite set of possible values

Analog Data

data with values that change continuously, or smoothly, over time

Overflow Error

error from attempting to represent a number that is too large

Round-off Error

error from attempting to represent a number that is too precise. The value is rounded

Open Access

online research output free of any and all restrictions on access and free of many restrictions on use, such as copyright or license restrictions

Open Source

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

When does round off error usually happen?

when a number can be represented completely accurately (ex. pi) when there are not enough bits

Byte

8 bits

How many total numbers can be represented with an 8 bit binary system?

256

Convert the binary number 1001 to decimal.

9

What are the characteristics of lossy compression?

-compresses information so that the original is not obtainable -irreversible -some data lost in the process

What are some examples of open access?

-covid data -news links to free sites -free scientific journals

What are some examples of lossless compression?

-song lyrics compression widget -zip files

What are some examples of intellectual property?

-story -music -painting

Convert the number 20 to binary

10100

Your computer uses 4 bits to represent decimal numbers (0, 1, 2, 3 and so on) in binary. What is the SMALLEST number for which an overflow error occur?

16

What are the characteristics of lossless compression?

-compresses data in a way where the original is recoverable -can be reversed -saves some space (takes fewer bits)

Arman takes a picture with his smartphone which he subsequently posts online. Beatrice finds the picture online and posts a copy of it on her website with an attached Creative Commons license. Which of the following best describes who owns the photo? A) Arman owns the photo because he was the original creator and did not license the work. B) Arman owns the photo because it was granted a Creative Commons license by another person online. C) Beatrice owns the photo because only holders of a Creative Commons license can work online. D) Both own the photo because creating a copy makes it her intellectual property.

A

Lossless Compression

a process for reducing the number of bits needed to represent something without losing any information. This process is reversible.

Decimal

a system for representing numbers using combinations of the digits 0-9

Binary

a way of representing information using only two options

Intellectual Property

a work or invention that is the result of creativity, such as a piece of writing or design, to which one has rights and for which one may apply for a patent, copyright, trademark, etc.