comp sci study guide 3

UNICODE

Unicode provides a unique number for every character, no matter what the platform, no matter what the program, no matter what the language. used internationally.

Convert the hexadecimal number A3 to its decimal representation.

163

Metadata

Data about data. Metadata describes how and when and by whom a particular set of data was collected, and how the data is formatted. Metadata is essential for understanding information stored in data warehouses and has become increasingly important in XML-based Web applications.

Data

Data is distinct pieces of information, usually formatted in a special way. All software is divided into two general categories: data and programs. Programs are collections of instructions for manipulating data.

Classify each of the following file types JPG, GIF, BMP, TIFF, MP3, WAV, PNG and PSD as lossy compression, lossless compression, or not compressed.

JPG-lossy GIF-lossless BMP-not compressed TIFF-losless MP3-lossy WAV-losless PNG-losless PSD-losless

Binary representation of data

a type of data that is represented or displayed in the binary numeral system; the only category of data that can be directly understood and executed by a computer; numerically represented by a combination of zeros and ones

RGB

an additive color model in which red, green, and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue

Convert the decimal number 76 to binary.

1001100

Convert the binary number 101101 to decimal

45

Convert the decimal number 76 to hexadecimal.

4C

ASCII

American Standard Code for Information Interchange. It is a code for representing 128 English characters as numbers, with each letter assigned a number from 0 to 127. For example, the ASCII code for uppercase M is 77. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.

What is the difference between lossy and lossless compression? Which (lossy or lossless) would be most appropriate for each of the following and why ? a. An image saved to be studied by brain surgeons while performing delicate surgery. b. An image uploaded to use on a personal webpage. c. A sound file used as background music for a home video where the song and video are to be uploaded to YouTube. d. A .zip file used to store a directory of documents. e. An image used as a thumbnail on your computer.

Lossy is usually used for video, sound, and photos. Lossless is usually used for texts, spreadsheets, or GIFs. a. Lossless b. Lossy c. Lossy d. Lossless e. Lossy

Lossy and lossless compression

Lossy: Refers to data compression techniques in which some amount of data is lost. Lossy compression technologies attempt to eliminate redundant or unnecessary information. Most video compression technologies, such as MPEG, use a lossy technique. Lossless: Refers to data compression techniques in which no data is lost. The PKZIP compression technology is an example of lossless compression. For most types of data, lossless compression techniques can reduce the space needed by only about 50%. For greater compression, one must use a lossy compression technique. Note, however, that only certain types of data -- graphics, audio, and video -- can tolerate lossy compression. You must use a lossless compression technique when compressing data and programs.

Hexadecimal

Refers to the base-16 number system, which consists of 16 unique symbols: the numbers 0 to 9 and the letters A to F. For example, the decimal number 15 is represented as F in the hexadecimal numbering system. The hexadecimal system is useful because it can represent every byte (8 bits) as two consecutive hexadecimal digits. It is easier for humans to read hexadecimal numbers than binary numbers. To convert a value from hexadecimal to binary, you merely translate each hexadecimal digit into its 4-bit binary equivalent. Hexadecimal numbers have either an 0x prefix or an hsuffix. For example, the hexadecimal number 0x3F7A A base-16 number system that uses sixteen distinct symbols 0-9 and A-F to represent numbers from 0 to 15.

Octal

Refers to the base-8 number system, which uses just eight unique symbols (0, 1, 2, 3, 4, 5, 6, and 7). Programs often display data in octal format because it is relatively easy for humans to read and can easily be translated into binary format, which is the most important format for computers. In octal format, each digit represents three binary digits, as shown: With this table it is easy to translate between octal and binary. For example, the octal number 3456 is 011 100 101 110 in binary.

An RGB color represented by the triplet (220, 65, 43) is closest in color to which of the components, RED, GREEN, or BLUE. Explain your answer.

The color represented by the triplet is closes in color to RED because Red is using 220 bits and stands out the most compared to green which is only using 65 and blue which is only using 43. 8

How does the computer distinguish between a photo and a text file if everything is stored as bits?

The computer distinguishes between different types of files through file extensions.An extension such as .doc, .txt, or .rtf indicates a text. An extension of .jpeg, .jpg, or .psd indicates a picture. These extensions tell the operating system what file it is and how to open it.