Objective:
This section introduces you to the basics of how computers work, including their use of the binary number system and the encoding of digital media files. After finishing this section, you should be able to:
- Describe the binary number system used by computers to process data.
- Define bits and bytes.
- Explain how physical signals are translated into digital information.
- Describe the most common units of measurement used for storage, throughput, and processing speed.
- Describe how audio and video are stored digitally.
- Distinguish between raster and vector images.
- Select the best format for digital images.
- Describe how RGB values determine pixel color.
- Compare common image file types.
- Describe the difference between lossless and lossy compression algorithms.
Links:
- TestOut Courseware: https://testout.com
Key Terms:
- Decimal System A numbering system that uses ten digits, 0 through 9.
- Binary System A numbering system that uses two digits, 0 and 1.
- Hexadecimal System A numbering system that uses sixteen digits, 0 through 9, and A through F.
- Bit The smallest unit of digital information, represented by a 1 or 0.
- Byte A group of eight bits joined together. Digital Data A physical signal, such as text, numbers, graphics, or sound, interpreted by converting it into binary numbers.
- Encoded Integers The representation of integers using a group of bytes. Normally, one bit in one of the byes represents the sign, 1 for negative and 0 for positive. The remaining 31 bits are used to encode the number itself using binary digits.
- Encoded Text The representation of text by assigning a unique binary code to each character.
- Processor Speed The speed at which a computer processes information, as measured by the number of cycles per second (Hertz) that the computer’s CPU operates at. Processor speed is measured in kilohertz, megahertz, and gigahertz.
- Storage Space The measurement in bytes of the volume that a storage device can contain. Storage space is measured in kilobytes (1024 bytes), megabytes (1024 kilobytes), gigabytes (1024 megabytes), and terabytes (1024 gigabytes).
- Throughput The measurement in bits per second that information is transferred through a network from one computer to another. Throughput is measured in Kbps (kilobits per second), Mbps (megabits per second), and Gbps (gigabits per second).
- ASCII Pronounced ask-ee and short for American Standard Code for Information Interchange, the most common format for text files in computers on the internet where each character is represented by a unique 7-bit binary code. Extended ASCII uses an 8-bit binary code and allows for international characters.
- Unicode An international 16-bit encoding standard that accommodates character sets from multiple languages, with each letter, digit, or symbol being assigned a unique numeric value.
- Sample The part of a sound wave that is captured, measured, and assigned a numeric value during digital sound recording.
- Bit Depth The amount of memory used to store the numeric value of a sound sample during digital sound recording. 8-bit sound uses eight bits (or one byte) to store the value of each sample. 16-bit sound uses two bytes per sample. Generally speaking, the better the bit depth, the better the sound.
- Sampling Rate The number of individual samples taken each second during digital sound recording. Measured in Hertz, the higher the sampling rate, the better the recording. Most modern sound recordings are made at 44.1 kHz.
- Frame Rate The number of images, or frames, that are taken each second during digital video recording. Most digital videos have a frame rate of about 30 frames per second.
- Resolution The number of pixels in the width and height of each frame in a digital video recording. The higher the resolution, the clearer the image will be.
- Color Depth The amount of memory the computer uses to display colors in a digital image or a digital video. 8-bit color images use one byte of data for each pixel. 24-bit color uses three bytes for each pixel.
- RGB Display A display on a computer monitor that is made up of sets of tiny red, green, and blue (RGB) lights, each set combining to make a pixel. A pixel will display different colors depending on the brightness of each light.
- Raster Images Images stored by dividing a picture into rows of pixels and collecting the color values of each pixel, in order, row-by-row.
- Vector Images Images stored by mathematically describing the shapes in the image. A circle might be stored as a center point and the distance from the center point to the circle’s edge. A square is stored as four lines, each with a beginning point and a length. More complex shapes can be stored as a set of small lines.
- File Compression A way of reducing the size of files, making them easier to store.
- Lossless Compression A compression algorithm, such as GIF, PNG, PDF, and ZIP, that doesn’t affect the original data. A file compressed using a lossless compression algorithm, when decompressed, will be exactly the same as the file before compression, bit for bit.
- Lossy Compression A compression algorithm, such as JPG, MP3, and MP4, that slightly alters the data to make it easier to store, taking advantage of the limitations of human sight and hearing, and is usually used for images, videos, and audio files.
- Run-Length Encoding A common lossless compression algorithm that looks for repeated patterns of bits or bytes and records the pattern and then number of times the pattern is repeated.
- Compression Artifact A patch of pixels in a compressed image or video that have less visible detail than the rest of the image.
Topics Discussed:
- How do computers convert physical signals into digital data?
- How do computers encode digital image, sound, video and text files?
- When is it best to use compressed files? When is it better to use uncompressed files?
Assignment:
- Access the TestOut Courseware through the provided link.
- Study Section 1.2: How Computers Work, and complete the 13 question Exam to complete the Section.
Assigned: August 29th, 2019
Teacher Pacing Due Date: August 30th, 2019