Computer Display Engineering Practice Flashcards

This set covers technical definitions, coordinate systems, transformations, and display algorithms from the Computer Display Engineering lecture notes.

CRT (Cathode Ray Tube)

A monitor type using a fluorescent screen to display pixels; features include low cost, true color quality, and high durability, but it is heavy and consumes a lot of electricity.

LCD (Liquid Crystal Display)

A monitor type that operates on the principle of blocking light; features include high brightness and sharpness, but it may have low pixel density leading to poor visibility in direct sunlight.

PDP (Plasma Display Panel)

A monitor known for vivid colors and wide viewing angles, though it tends to consume significant power and heat up easily.

Screen Size Calculation

Measured in inches, determined by the diagonal length between two opposite corners of the screen (excluding the bezel), where $1\,inch = 2.54\,cm$.

Screen Resolution

The maximum number of pixels that can be displayed on a screen, represented by dimensions such as $640 \times 480$ or $1024 \times 720$.

Aspect Ratio

The ratio of vertical points to horizontal points required to generate a unit length line in both directions on the screen (e.g., a $3/4$ ratio means $3$ vertical points equal $4$ horizontal points).

Frame Buffer

A memory region that stores the color values of all points on the screen, maintaining a bijective (one-to-one) relationship with the display.

Refresh Rate

The number of times the image on the screen is updated per second, measured in $Hz$; standard LCDs typically range from $60$ to $144\,Hz$.

RGB Color Space

A color system built on three primary colors: Red, Green, and Blue, where each color is a combination of these three base values.

HSL Color Space

Represented by Hue, Saturation, and Lightness in a cylindrical coordinate system limited within two cones joined at their bases.

HSV Color Space

Represented by Hue, Saturation, and Value in a cylindrical coordinate system limited within a single cone.

Graphics Application

Software designed for non-programmers to create images without needing to understand the underlying generation process, such as AutoCAD or Adobe Photoshop.

Positive Coordinate System

A Cartesian system where points are described by pairs of real numbers, the origin is $(0,0)$, and positive directions follow the right-hand rule.

Negative Coordinate System

A system where the origin is $(0,0)$ but the positive direction of the $Oy$ axis is reversed compared to the positive system; commonly used in computer graphics and robot control.

Device Coordinate System

Used by specific output devices like monitors or printers; points are discrete, and for computer screens, the origin $(0,0)$ is the first pixel at the top-left corner.

Polyline Data Requirements

To display a specific polyline, the system requires the coordinates of the vertices, attributes like color and thickness, and the drawing method (straight or curved).

Linear Transformation

A transformation of an object's points using linear operations, including rotation, scaling, and translation.

Translation

Moving an object by shifting all its points by a fixed vector; applying two successive translations results in a new translation where the vector is the sum of the two original vectors.

Scaling Transformation

Enlarging or shrinking an object by a fixed ratio; applying two successive scaling operations results in a new scaling transformation where the ratio is the product of the original ratios.

Homogeneous Coordinates

A coordinate system used to represent geometric transformations (like translation) as matrix multiplications.

Rotation (2D)

Geometric transformation where a point is rotated around the origin by an angle $\theta$; applying two successive rotations results in a single rotation by the sum of the two angles.

Spherical Coordinate System (3D)

A system where a point's position is defined by three values: the radial distance $r$ from the origin, the elevation angle $\theta$, and the longitude angle $\phi$.

Wireframe Model

A 3D object representation consisting of a set of vertices and the edges connecting them.

Parallel Projection

Uses parallel lines passing through object vertices; it preserves alignment, order of points, and parallel relationships but does not provide a realistic 3D representation.

Perspective Projection

Uses lines passing through object vertices that converge at a center point; it produces a more realistic image where object size changes relative to the distance from the projection plane.

Polygon Mesh

A method of representing 3D objects using a grid of small polygons (usually triangles or quadrilaterals) joined together.

Z-buffer (Depth-buffer) Algorithm

A hidden surface removal method that uses a depth buffer to store the minimum $z$ coordinate at each pixel to determine visibility.

Scan-line Algorithm

A hidden surface removal method that checks the intersections of all polygon surfaces for each horizontal scan line to determine visible segments.

Depth-sort Algorithm

A hidden surface removal technique that sorts surfaces by depth in descending order and draws them from the furthest to the nearest.

Area-subdivision Algorithm

A method that recursively divides an image into smaller regions until each sub-region is simple enough to be displayed without depth testing.

Ambient Light (Background Light)

Light that reaches an object from all directions after multiple reflections off surrounding objects.

Refraction

The process where light changes direction as it passes from one medium into another with a different refractive index, following Snell's Law.

Halftoning

A method used to display various light intensities on a screen.