1.2 Text, sound and images Flashcards
(20 cards)
How does a computer represent text?
Text is converted into binary using a character set, which is a collection of characters and corresponding binary codes that represent them.
What is the ASCII character set?
ASCII (American Standard Code for Information Interchange) is a 7-bit code that represents letters, numbers, and characters found on a standard keyboard, as well as 32 control codes.
What is the ASCII value of the letter “a”?
The ASCII value of “a” is 97.
How do uppercase and lowercase letters differ in ASCII?
In ASCII, uppercase and lowercase letters have different values. For example, “A” is 65 and “a” is 97. The difference is due to the change in the sixth bit when converting from lowercase to uppercase.
What is Unicode and how does it differ from ASCII?
Unicode is a character set that supports a much wider range of characters than ASCII, including different languages, symbols, and emojis. It can store up to four bytes per character, whereas ASCII uses just one byte.
Why is Unicode used instead of ASCII?
Unicode is used because ASCII does not support all international languages and symbols, while Unicode allows for a broader range of characters, making it more versatile.
How does a computer represent sound?
Sound is analogue, but to be processed by a computer, it is converted to digital form through a process called sampling, where the amplitude of the sound wave is measured at regular intervals.
What is sampling resolution (bit depth)?
Sampling resolution, or bit depth, refers to the number of bits used to represent each sample of a sound wave. Higher bit depth results in more accurate sound representation, but increases file size.
What is the sampling rate?
The sampling rate is the number of samples taken per second when recording sound, measured in Hertz (Hz). A higher sampling rate results in more accurate sound.
How does the sampling rate affect sound quality?
A higher sampling rate results in a more accurate sound recording, as it reduces the gap between samples, leading to better quality.
How is an image represented in a computer?
A bitmap image is made up of pixels, each representing a small part of the image. The image is stored as a series of binary numbers corresponding to the pixels.
What is colour depth in an image?
Colour depth refers to the number of bits used to represent the colour of each pixel. For example, an 8-bit colour depth allows for 256 colours, while a 1-bit depth allows for two colours (black and white).
How does colour depth affect file size?
Increasing the colour depth increases the file size because more bits are used to store the colour data for each pixel.
What is image resolution?
Image resolution refers to the number of pixels that make up an image. A higher resolution means more pixels and more detail, while lower resolution results in less detail.
What happens to an image when its resolution is low?
A low-resolution image may appear blurry or pixelated, especially when zoomed in, as there are fewer pixels to represent the image.
How does image resolution affect memory usage?
Higher-resolution images use more memory because they contain more pixels, requiring more data to represent the image.
What does it mean when an image is pixelated?
Pixelation occurs when an image has low resolution, and individual pixels become visible, causing the image to appear blurry or blocky.
How many colours can a 1-bit colour depth image store?
A 1-bit colour depth image can store only two colours: typically black and white.
How does increasing the resolution and colour depth of an image affect its quality and file size?
Increasing the resolution and colour depth improves the image quality by adding more detail and colours, but it also increases the file size because more data is required to store the image.
How is sound converted to digital form?
Sound is digitized by sampling the amplitude of the sound wave at regular intervals. These samples are then converted into binary numbers and stored as digital data.
