Computer Science 1033A/B Study Guide - Final Guide: Desktop Publishing, Word Processor, Coreldraw

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GRAPHICS
We rely on images for Information, explanations, entertainment
Graphics originate from: non-digital medium (paper copy of a photo), outside world, create image
DIGITIZATION: the process of translating a piece of information (text, images, sound recording,
video) into BINARY BITS
BIT: short for Binary Digit, value of “1” or “0” – fundamental units of information in a
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When press a key, binary code sent to RAM (memory) CPU Video card On
screen
Measurement system binary system (base of 2, exponent = number of bits)
BYTE: collection of 8 bits (28) = 256 possible combinations of 1s and 0s
Ex: 21 = 2 values (0, 1), 22 = 4 values (00, 01, 10, 11)...
IMAGE: represented by a grid (array, matrix) of squared picture elements called PIXELS (the
smallest image component and thus shows the smallest detail)
Pixel numerical value corresponding to a COLOR INDICATOR (bw or colour)
RGB Code
Hexadecimal Code
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een 640 dots on each of 480 rows 300,000 pixels
Coding colors
Black/white = 1 bit ONLY (0 = black, 1 = white)
2 bits combination of black and white (01/10) grey
More bits, more shades... 4 bits 24 = 16 grey shades
Used for web
Used for printing
Additive Model (RGB)
Subtractive Model (CMYK) (k=black)
Primary colours: Red, Green, Blue
Primary colours: Cyan, Magenta, yellow
added” to a black background in order to obtain
color shades
subtracted” from a white background
In “TRUE COLOR” each pixel represents some color shade – Uses 24 bit representation = 16
million colors
Color can be expressed in:
RGB does not = Hexadecimal, need converter
Cathode ray tube devices (such as computer monitors) can only display colour with red,
green and blue light this is the color system of the web
Each pixel is represented by 3 values
-ie: light yellow = <255,255,127> <R,G,B>
Syntax:
Each value ranges from 0-255
256 color shades = 28 bits
-16 million colors in the spectrum (2563)
-consists of 16 unique symbols:
0,1,2,3,4,5,6,7,8,9,E, and F
-color represented by 6 digits: ie, #FFCC66
Red: <255,0,0>
Green: <0,255,0>
Blue: <0,0, 255>
Red: #FF0000
Green: #00FF00
Blue: #0000FF
-Web-safe colors: only 1,3,6,9,C,F
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Types of Graphics Bitmap or vector effects how graphics are displayed on a computer screen:
Quality, file size, time to display graphics
BITMAP (zoom in to pixels)
VECTOR (zoom in, no pixels)
-images made up of small squares called Pixels
-Editing pixels: changing color, shade, brightness
Advantages of using a small image rather than larger:
-shorter time needed to display on screen
-smaller file size
Disadvantages:
-distortion occurs when image is enlarged
-image is represented with lines and arcs that have a
mathematical relationship
-describes the drawing of the shape
- Line: starting point, direction length
- Rectangle: start point, width height
- Circle: center and radius
*SMALLER FILE: records mathematical relationship
-as image is enlarged (resized):
- Dots become larger, edges more jagged
- Quality decreases
- File size increases
-as image enlarged (resized):
- Dots become larger, edges still clean, crisp
- Quality is maintained no distortion
- File size increase
**Vector CANNOT be converted to Bitmap, but Bitmap CAN be converted to vector
BITMAP-BASED programs “PAINT”
VECTOR Graphics programs “DRAW”
-ability to edit an image’s pixels
-images from scanners, cameras
-need a “PAINT” program
-greater control and precision with free-hand tool
-display more accurately on screen
-download faster because support of Flash and Scalable
Vector Graphics (SVG formats)
-produce smaller files that download faster
-more details in vector-based illustrations
-must use a “DRAW” program – draw and edit paths
Photoshop, paintshop pro, photoplus
(but photoshop v6.0 has vector features)
Adobe illustrator or Macromedia FreeHand, Corel Draw
Graphic Attributes IMAGE QUALITY: Image resolution, image bit depth
IMAGE RESOLUTION (ppi/dpi): the number and spacing of pixels in an image
The number of pixels per square inch on a computer-generated display
Ex: if resolution 100 ppi, each pixel 1/100th inch
When you increase the number of pixels, increase quality of detail in the
resolution
For different output delivery:
Web set to 72 dpi (smaller graphics, don’t see detail)
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