Monitor and Graphics Technologies: A Deep Dive
CRT (Cathode Ray Tube) Monitors
CRT monitors were once the most common type. They work by directing red, green, and blue electron beams across a phosphorus-coated screen. The phosphor glows when struck by the electron beam, while areas not struck remain dark. The combination of glowing and non-glowing areas creates the image.
LCD (Liquid Crystal Display) Monitors
LCD monitors consist of two polarizing filters with a liquid crystal solution between them. An electronic current aligns the crystals, allowing light to either pass through or be blocked. This process creates the image.
TFT (Thin-Film Transistor) LCD
LCDs come in two main formats: active matrix (TFT) and passive matrix. Active matrix (TFT) technology allows each pixel to be controlled individually, resulting in sharper color images.
Plasma Displays
Plasma displays use the light emitted from plasma generated during a gas discharge. Electrodes supply voltage and create the plasma. Because the electrodes are directly exposed to the plasma and conduction current flows directly through them, this is considered a direct current type of display.
Key Monitor Specifications
Refresh Rate
Refresh rate refers to how many times per second the image is rebuilt. A higher refresh rate (e.g., 120Hz, 240Hz) produces a better image and reduces flicker.
Aspect Ratio
Aspect ratio is the horizontal-to-vertical measurement of the monitor’s viewing area. For example, a 4:3 aspect ratio could apply to an area that is 16×12 inches.
Color Depth
Color depth is the number of bits used to indicate the color of a single pixel (in a bitmapped image or video frame buffer) or the number of bits used for each color component of a single pixel. For example, 24-bit color depth is common.
Dot Pitch
Dot pitch is the distance between pixels on the screen. A lower dot pitch number (e.g., 0.18mm vs. 0.31mm) produces a sharper image.
Pixel Response Time
Pixel response time measures how quickly a colored pixel can turn to white and then back to a color. An example is 16.67ms.
Resolution
Resolution is the number of distinct pixels in each dimension that can be displayed. For example, 1024×768 means a width of 1024 pixels and a height of 768 pixels.
Color Models
RGB Color Model
RGB is an additive color model based on combining red, green, and blue light. These are primary additive colors because when combined in equal amounts, they produce white. The RGB model is primarily used for sensing, representing, and displaying images in electronic systems like televisions and computers.
CMYK Color Model
CMYK is a subtractive color model used in color printing. CMYK refers to the four inks used: cyan, magenta, yellow, and key (black). It’s primarily used in printers.
Graphics Types
Raster Graphics
Raster images are composed of pixels. Scaling up a raster image often results in quality loss. Enlarging a raster image can be done by adding more pixels or increasing the size of existing pixels. Modern computer monitors typically display between 72 and 130 pixels per inch. Converting raster images to vector graphics can be time-consuming.
Vector Graphics
Vector graphics are created using mathematical calculations that define objects and lines. They do not use pixels and are therefore resolution-independent, meaning they can be scaled without loss of quality. Vector graphics can be easily converted to raster format and typically have smaller file sizes.
Audio Sampling and Compression
Sampling
Sampling in digital audio involves capturing the state or quality of a sound wave at a set number of times per second. The x-axis represents the sampling rate (how many samples are taken per second), and the y-axis represents the sampling precision (or bit depth), which indicates how many bits are used to describe the sound’s characteristics.
(Graphic)
Higher sampling rates and greater precision result in better audio quality.
(Graphic)
Closer lines indicate higher fidelity. Amplitude represents loudness, while timbre distinguishes the same note played on different instruments.
Compression Rate in MP3 Files
When compressing a WAV file to MP3, the bit rate is crucial. The bit rate is the amount of information (number of bits) transferred from the compressed file to the MP3 decoder per second. Higher bit rates generally mean higher sound quality. MP3 bit rates are commonly measured in kilobits per second (Kbps), with most encoders supporting rates from 24Kbps to 320Kbps.