1. CHAPTER 05: GRAPHICS TECHNOLOGY
~ Introduction ~
~ Bitmap versus vector ~
~ Colors system ~
~ Image editing~
~ 3-D image models ~

2. introduction

3. Graphics Technology Introduction Backbone of multimedia product.
There are many sources to present graphics; picture, image, clip art, etc.
Provide backgrounds, informational contents, and navigational controls.
Graphics are created using a variety of tools such as paint/drawing software, scanners, and digital cameras.
Graphics are stored in files in variety types of formats, depending on the size and quality.

4. Graphics Technology Elements of graphics
Pictures versus images ??? Both are two levels of graphics abstraction.
Pictures are found in the world external to the computer while images are 2D representations of pictures found in computers.
Look and feel
Easy to store
Two basic approaches: Raster or bitmap images & Vector or metafile images.

5. Raster/bitmap images

6. Raster / Bitmap Images
The most common and comprehensive form of storage.
Looks as much as possible like the real-world or original product – accurate.
Created as 2D sets of points on a computer display (each point can display from two to millions of colours).
Points made up of a matrix of elements called pixels.
Really depends on hardware capability.

7. Raster / Bitmap Images Where do bitmaps come from:
Make a bitmap from scratch with a paint or drawing program.
Grab from an active computer screen with a screen capture program, and then paste it.
Capture from a photo or artwork, using a scanner or digital camera or video capture device that digitizes the image

8. Raster / Bitmap Images Technically characterized by
the number of bits per pixel or color depth or intensity level, which determines the number of colors it can represent
the width and height of the image in pixels or spatial resolution
Determine the quality and size of the images

9. Raster / Bitmap Images Color depth (Intensity Level)
Colour depth is determined by how much data, in bits, is used to determine the number of colours.
1 bit yields 2 colours
4 bits yields 16 colours
8 bits (1 byte) yields 256 colours
16 bits (2 bytes) yields 65,536 colours
24 bits (3 bytes) yields 16,777,216 colours

10. Number of Intensity Levels
Raster / Bitmap Images
Number of Bits
Number of Intensity Levels
Examples 1 2
0, 1 2 4
00, 01, 10, 11 4 16
0000, 0101, 1111 8
256 , 16
65,536

11. Raster / Bitmap Images
Monochrome display: each pixel is most commonly set to black or white (1 bit) also called as a binary image

12. 8 bits per pixel allows 256 distinct colors
Raster / Bitmap Images
8 bits per pixel allows 256 distinct colors
BMP – 119KB

13. Raster / Bitmap Images
16 bits per pixel represents 32K distinct colors (Most graphic chipsets now supports the full colors and the color green uses the extra one bit)
BMP – 234 KB

14. Raster / Bitmap Images 24 bits per pixel allows millions of colors
BMP – 350KB

15. Raster / Bitmap Images
More bits provide more color depth, hence more photo-realism,
but require more memory and processing power
Graphics production software may capture in 24-bit color and convert to 8-bit

16. Raster / Bitmap Images
This example zoomed in at 500% illustrates how several small pixels make up a raster image.

17. Raster / Bitmap Images

18. Raster / Bitmap Images Spatial Resolution
Is a number of pixels and is related to the size of image file.
Spatial resolution simply refers to the smallest discernable detail in an image
Vision specialists will often talk about pixel size
Graphic designers will talk about dots per inch (DPI)
5.1 Megapixels

19. Raster / Bitmap Images
1024 Resolution

20. Raster / Bitmap Images
512 Resolution

21. Raster / Bitmap Images
256 Resolution

22. Raster / Bitmap Images
128 Resolution

23. Raster / Bitmap Images
64 Resolution

24. Raster / Bitmap Images 32 Resolution
From your observation, what you can conclude by the number of resolution?

25. Determining Size of Raster Images
Size can be determined by multiplying the number of pixels (spatial resolution) in the horizontal plane (x) by the number of pixels in the vertical (y), then take this value and multiply it by the number of bytes per pixels (bit depth).
image size (bytes) = x * y * (bits per pixel/8)
Example: A standard computer VGA display is 640 X 480 pixels for a total of 307,200 pixels. A two-color or monochrome display image consists of 38,400 bytes.

26. Determining Size of Raster Images (cont)
Try these: A standard computer VGA display is 640 X 480 pixels for a total of 307,200 pixels …
256-colour display images
24-bit colour
The more colours used, the more bytes are required to encode the image, and the more bytes required for an image, the larger the file to store the image.

27. Raster Image Formats
The most common file formats for graphics across most computer platform.
Offer a very accurate reproduction of an image based on its colour depth and resolution.
Easiest files to import and export at any platforms of computers.
PNG
TIFF
GIF
JPEG/JPG
BMP, MacPaint, and XBM

28. Raster / Bitmap Images Advantages: Disadvantages:
Realistic images (high colour depth)
Easy to edit
Can be compressed
Disadvantages:
File size is too big
Take more processor times to generate the image
Suffers from distortion problem (replication of pixels elements)

29. Vector images

30. Vector Images
Based on drawing elements or objects such as lines, rectangle, circles, etc.
Stored as commands that define the individual objects.
Scaling factor approach.
Advantages:
Small file size (less memory and disk usage).
Can be resized into larger image (no distortion problem)
Consists of a set of commands that are drawn when needed.
Easy to convert into bitmap format

31. Vector Images Disadvantages: Not realistic
Too many vector graphics on screen could increase processor time consumptions (too many mathematic functions must be calculated)
RECT 0,0,200,200,RED,BLUE

32. Vector Image Formats
Are common across many operating systems and a number of vendor specific applications.
Example: Windows metafile is generated by processing vector commands by graphic functions in the Windows operating system.
Commands are processed as a series of records that are loaded and executed in sequence.
Clip arts

33. Vector Image Formats
Windows Metafiles

34. Vector Images Applications of vector drawn:
i. Computer-aided design (CAD); for creating the highly complex and geometric renderings needed by architects and engineers
ii. Graphics artists design; for printed media without “jaggies”
iii. 3D animation program; for various changes of position, rotation, and shading of light (all must be calculated mathematically)

35. Vector Images

36. colors

37. Image and its colors Vital component of multimedia.
Picking right colours and combination of colours for multimedia involve many tries.
Eye’s receptors are sensitive to red, green, and blue.
Two basic methods of making color:
Additive color
Subtractive color

38. Computerized colors Additive Colour:
A colour is created by combining coloured light source in three primary colours: red, green, and blue (RGB)
Used for a TV or computer monitor
Electron beam
Combination creates all other colours

39. Computerized colors Subtractive Colour:
A colour is created by combining coloured media such as paint or ink that absorb some parts of the colour spectrum of light
Is the process used to create colour in printing
Made up of three primary colours: cyan, magenta, and yellow (sometimes black) - CMYK

40. Computer Color Models Red, Green, Blue (RGB) Colour System:
This system divides the colour signal into three channels: red(R),green(G),and blue(B).It is based on combination of additive primaries to produce colour mixtures
Using 24-bit model, each red, green, and blue are set to a value of 256 choices (0-255)
Eight bits of memory is required (8+8+8 = 24) to describe about 16.7 millions of colours

41. Computer Color Models Red, Green, Blue (RGB) Colour System:
Red only (255,0,0) Red
Green only (0,255,0) Green
Blue only (0,0,255) Blue
Red and Green, Blue subtracted (255,255,0) Yellow
Red and Blue, Green subtracted (255,0,255) Magenta
Green and Blue, Red subtracted (0,255,255) Cyan
Red, Green, and Blue (255,255,255) White
None (0,0,0) Black

42. RGB Color Models (0,0,0) = Pure black (1,1,1) = Pure white
Blue
Magenta
White
Cyan
Green
Red
Black
Yellow
(0,0,0) = Pure black
(1,1,1) = Pure white
(1,0,0) = Pure red
(0,1,0) = Pure green
(0,0,1) = Pure blue
(1,0,1) = Magenta

43. Computer Color Models HSB / HSL Colour System
Specifying hue or colour as an angle from 0 to 360 degrees on a colour wheel, and saturation, brightness, and lightness as percentages
Saturation is the intensity of a colour
At 100% saturation, a colour is pure; at 0% saturation the colour is white, black or grey
Lightness or brightness is the percentage of black or white that is mixed with a colour
A lightness of 100% will yield a white colour, 0% is black, and 50% is the pure colour

44. HSB Color Models HSB Colour System: Colour Degrees Red 0° Yellow 60 °
Green 120 °
Blue 240 °
Magenta 300 °
Saturation
Lightness & Brightness
Hue

45. Computer Color Models CMYK Colour System
Is less applicable to multimedia production
Used primarily in the printing purposes
Yellow
Green
Black
Red
Magenta
Cyan
White
Blue
(0,0,0) = Pure white
(1,1,1) = Pure black
Cyan + Yellow = Green

46. Image and its colors Colour Palettes
Computer manage colour via palettes or colour look-up tables, which are mathematical tables that define the colour of any particular pixel displayed and the total number of colours that can be displayed on a system.
Colour palettes are defined by indexing values correlated to red, blue, and green colours. The value ranges from 0 to 255.
Unique palette value.
When an image is displayed, its palette is mapped into the system palette.
Is a collection of colour values in a look-up table

47. Colour Palettes Colour-depth Colours Available
1-bit 2 colours (Black and white)
2-bit 4 colours
4-bit 16 colours
8-bit 256 colours (good enough for colour images)
16-bit 65,536 colours (excellent for colour images)
24-bit 16.7 millions colours (totally photo-realistic).

48. Colour Palettes

49. Computerized color Colour Dithering
Is a process whereby the colour value of each pixel is changed to the closest matching colour value in the target palette, using a mathematical algorithm.
Consider you have a scanned or digitised images that are captured at 24 bit, with 16 million of colour depth.
If this image is subsequently displayed on a computer monitor and system that is limited to less than 16 million colour depth (say 256 colours) the image must be transformed for display in the lesser colour palette.

50. Computerized color Colour Dithering
The image palette is mapped into the new palette dimensions with colours substituted with the closest available values.
The quality of dithering is depending on the algorithm used but most systems provide close approximations of the original

51. Computerized color Colour Dithering 32-bit color 4-bit color dithered

52. Computerized color http://giphy.com/search/flashing-colors
Colour Flashing
This is a phenomena when images change the basic colour palette.
It always happen with animation or consecutively displayed images with different palettes in each successive image.
When new images are loaded, the palette is mapped into the new set of colours and a momentary flashing can be observed that can be distracting to the viewer.
process to change the closest matching color value

53. File format

54. Image/Graphic Files Format
Most popular formats:
JPEG (Joint-Photographic Experts Group)
GIF (Graphical Interchange Format)
PNG (Portable Network Graphic)
Other formats:
BMP, PSD, TIFF/TIF, TGA, EPS, PCX, ICO

55. JPEG For continuous tone images, such as full-color photographs
Supports more than 16 millions of color (24-bit)
Uses lossy compression (averaging may lose information)

56. GIF For large areas of the same color and a moderate level of detail.
Supports up to 256 colors
Allows transparency and interlacing
Uses lossless compression

57. PNG lossless, portable, well-compressed storage of raster images
patent-free replacement for GIF
also replace many common uses of TIFF
Support indexed-color, grayscale, and true color images + an optional alpha channel for transparency

58. Other Formats BMP – Bitmap File Format. PSD – Photoshop Document.
Native bitmap file format of the Microsoft Windows environment.
PSD – Photoshop Document.
Native bitmap file format of the Adobe Photoshop graphical editing application.
TIFF – Tagged Image File Format.
Used to exchange documents between different applications and platforms.

59. Other Formats TGA – Targa File Format. EPS – Encapsulated PostScript
An image format designed for systems using Truevision video boards
supported by MS-DOS platforms.
EPS – Encapsulated PostScript
file format. Adobe drawing format supported by most illustration and page layout programs.

60. Other Formats PCX – ZSoft IBM PC Paintbrush file format.
One of the oldest bitmapped formats popularized by MS-DOS paint programs that first appeared in the early 1980's.
ICO – Icon file format.
Created by Microsoft for icons.

61. Editing

62. Editing Digital Images
Image Filtering
Filtering is a process of representing the range of intensities by sampling and approximation. The results of this process are much more precise,predictable,and efficient.
Involves manipulating and transforming pixel values as defined by a digital filtering function.
Original image is combined with a mathematical function to produce a new filtered image.
The resulting value is stored in the same pixel location for the output image.

63. Editing Digital Images
Image Filtering
Filtered image can be saved as a separate file,thus preserving the original for reuse in other applications.
There are two classes of filters: Global filter and Local filter

64. Editing Digital Images
Global Filtering
Transforms each and every pixel uniformly according to its filtering function regardless of its location and surroundings in the image.
Example: increasing the level of brightness / darkness

65. Editing Digital Images
Local Filtering
Transforms a pixel in relation to its surrounding neighbours in the image.
Example: sharpening the edges of objects in an image.
Also known as spatial filtering.
Edge detection

66. Edge Detection

67. Editing Digital Images
Retouching Process
Modification or editing of the content of an image.
2 general categories: painting and cloning methods.
Painting: draw and work on a particular image,provide a number of tools(pencil,brush,area-fill,etc).
Cloning: is a method whereby a selected area of an image is duplicated and pasted as many times as we desire to any image.

68. Editing Digital Images
Image Composite
Combines components from two or more images into a single,seamless image.
The basic idea is select the portions of any particular image and paste it together as needed.
Can be a difficult and timely process.

69. Editing Digital Images
Image Composite
Image layering.
An image layer is a separate image channel that ordinarily contains an object that can be manipulated separately from the background or earlier scene.
Objects in the topmost
layer are always visible.
Layers are independent.

70. Editing Digital Images
Digital Warping
A process that uses geometric operations to transform the structure of any particular images.
Both still images and non-still images can be cooperated.
Selecting key points are the most crucial part.
For example,to change a person's facial expression by simply selecting certain key points in the original image and warping them in the output image
A warp function describes the geometric transformation that is performed on the coordinates of the pixels affected.

71. The transformations in digital warping

72. Image/graphic : information delivery

73. Graphic - Information Delivery
Graphics are used to convey information in multimedia products.
For example, a picture of an automobile engine is much more effective than text that merely describes it.

74. Graphic - Information Delivery
Graphics for information delivery include:
Drawn images
Charts and graphs
Maps
Scenery
People

75. Graphic - Information Delivery
In each case, the image must be relevant to the overall product.
Image size, color in respect to the application and other images, and positioning must all be considered when using images.

76. Graphic - Information Delivery

77. Graphic - Information Delivery

78. Graphic - Information Delivery

79. 3D Graphics

80. Three Dimensional Graphics
Can be divided into two categories: Volume-based graphics and Surface-based graphics.
Volume-based graphics:
Voxels have features such as colour,intensity,transparency,and opacity.
Medicine,physics,chemistry,and meteorology

81. Three Dimensional Graphics
Surface-based graphics:
Create a photo realistic illusion of three dimensional objects rather than manipulating them as solids.
Requires a high performance computer systems running application programs written especially for them.

82. Three Dimensional Graphics
3-D Modelling and Development Stages :
1. Model Description
Solid modelling :
Portrays objects as derived from simple 3-D solids that serve as primitives within the system.
For examples, cubes, cylinders, spheres, and cones can be organized, adapted, and reshaped to model some complex object.

83. Three Dimensional Graphics
Polygon-surface modelling :
A collection of connected 2-D polygons of various shapes.
Multifaceted figures.

84. Three Dimensional Graphics
Wireframe modelling :
Composed of a series of connected shapes (like polygon-surface models-that are joined to others at their vertices).
It may embrace curved shapes.
In most 3-D applications, you can create any 2-D shape with a drawing tool or place the outline of a letter, then extrude or lathe it into the third dimension along the z axis
Lathing creates a model by rotating a two-dimensional outline around a given axis.
Extrusion lifts or adds a third dimension to a two-dimensional outline.

85. Three Dimensional Graphics
Lathe
A free-form object created by extrusion and a wine flute created by lathing
Extrude
When you extrude a plane surface, its shape extends some distance, either perpendicular to the shape’s outline or along a defined path. When you lathe a shape, a profile of the shape is rotated around a defined axis (you can set the direction) to create the 3-D object.

86. Three Dimensional Graphics
2. Scene Description
Once the objects for an image have been modelled,they must be arranged to form a scene.
Most 3-D applications provide a library of surfaces and backgrounds.
Designer may also import any other images from other graphic applications that can serve as backgrounds as well.

87. Three Dimensional Graphics
2.1 Shading
Creating the illusion of photo realism.
Lambert / Flat Shading:
Is the fastest for the computer to render (simplest lighting and shading model)
Often used in
preview mode
Lack of subtlety

88. Three Dimensional Graphics
Gouraud Shading:
Is more realistic than flat shading
Concern on the lighting effects on the surrounding surfaces and calculates shading from each vertex
The shading values for pixels between two vertices are interpolated to create a more diffuse or smoothly varying effect.

89. Three Dimensional Graphics
Phong Shading:
Recomputed the illumination model for each pixel
Results are much more realistic,though the process is more time-consuming

90. Three Dimensional Graphics
Ray Tracing Shading:
Concern on light rays that are reflected from other objects
This can be traced by determining what other surfaces they contact
Striking results for scenes with mirror or glass-like surfaces
Extremely time-consuming

91. Three Dimensional Graphics
3. Rendering
When you have completed the modelling of your scene or an object in it, you then must render it for final output.
Rendering is when the computer finally uses intricate algorithms to apply the effects you have specified on the objects you have created.
Will blend together

92. Three Dimensional Graphics
object
background
A background and object rendered into an image with shadows and lighting effects
final production