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Introduction to Multimedia

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Introduction to Multimedia SMM 2005 * 3D Object Modeling involves drawing a shape, such as a 2D letter, then extruding it or lathing it into a third dimension. – PowerPoint PPT presentation

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Title: Introduction to Multimedia


1
Introduction to Multimedia
  • SMM 2005

2
Introduction to Multimedia
  • Chapter 4

3
Graphics Overview
  • Key feature/element in multimedia products
  • Most of the time, using text only is not enough
    to convey a message to the user.
  • Multimedia products need attractive graphical
    combination and presentation
  • Developers must understand the purpose and
    significance of graphics that are going to be
    used in their projects
  • Also important in information delivery.

4
Graphics Overview
  • Graphics can be developed using several methods
  • Illustration software
  • Graphic/image manipulation software
  • Acquiring through scanning or camera transfer
  • Graphic files can be stored in various file
    format each format has different purposes

5
4.1 Elements of Graphic
  • To create a remarkable graphics, developer must
    understand graphics and its elements
  • Lines
  • Shapes
  • Space
  • Texture
  • Color

6
Lines
  • A mark with length and directions
  • Continuous mark made on some surface by a moving
    point
  • Types of line include vertical, horizontal,
    diagonal, straight or ruled, curved, bent,
    angular, etc.

7
Shapes
  • Enclosed space defined and determined by other
    art elements such as line, color, value, and
    texture
  • Can appear as 2 dimensional (2D) or 3 dimensional
    (3D)

8
Space
  • Refers to the distance or area between, around,
    above, below, or within things
  • can be described as two-dimensional or
    three-dimensional as flat, shallow or as
    positive or negative space etc

9
Texture
  • Surface quality or "feel" of an object, its
    smoothness, roughness, softness, etc
  • Actual or Simulated

10
Texture
  • Actual textures - can be felt with fingers
  • Simulated textures - suggested by an artist in
    the painting of different areas of a picture

11
Color
  • Produced by light of various wavelengths - when
    light strikes an object and reflects back to the
    eyes

12
Color
  • An element of art with three properties
  • hue or tint (the color name)
  • intensity (purity and strength of a color)
  • value (the lightness or darkness of a color)
  • Photographers measure color temperature in
    degrees Kelvin (K).

Description Degrees Kelvin
Clear Blue Sky 8000 to 27,000
Rainy, Misty Daylight 7200 to 8500
13
Graphics Image Development
  • Graphical images obviously play a very important
    role in multimedia products
  • Images may be photograph-like bitmaps,
    vector-based drawings, or 3D renderings
  • Access to the right tools and right hardware for
    image development is important!
  • E.g., graphic designers like to have large,
    high-resolution monitors or multiple monitors

14
Graphics Image Development
  • Still images are generated in two ways
  • bitmaps (or raster-based)
  • vector-drawn

15
Generating still images Bitmap
  • Bitmap - a matrix describing the individual dots
    that are the smallest elements (pixels) of
    resolution on a computer screen or printer

16
Generating still images Bitmap
  • Example

17
Generating still images Bitmap
  • Monochrome just requires one bit per pixel,
    representing black or white

BMP 16 KB
18
Generating still images Bitmap
  • 8 bits per pixel allows 256 distinct colors

BMP 119KB
19
Generating still images Bitmap
  • 16 bits per pixel represents 32K distinct colors
    (Most graphic chipsets now supports the full
    65536 colors and the color green uses the extra
    one bit)

BMP 234 KB
20
Generating still images Bitmap
  • 24 bits per pixel allows millions of colors

BMP 350KB
21
Generating still images Bitmap
  • 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

22
Generating still images Bitmap
  • GIF and PNG formats use a 8-bit color table
    allowing up to 256 color

GIF 74KB
PNG 63KB
23
Generating still images Bitmap
  • JPG preserves more color depth with 16 bits per
    pixel

JPG 19KB
24
Generating still images Bitmap
  • Bitmaps are best for photo-realistic images or
    complex drawings requiring fine detail

25
Generating still images Bitmap
  • Bitmaps picture and their suitability of use-
  • Use the native Microsoft bmp format as a raw
    image that will later be processed. It faster to
    process.
  • Use JPEG, for photo sharing on the web because of
    its size and quality.
  • GIF is normally used for diagrams, buttons, etc.,
    that have a small number of colours
  • It is also suitable for simple animation because
    it supports interlaced images.
  • PNG is almost equal to gif except that it didnt
    support the animation format.

26
How to Create Bitmap Graphics
Clip Art
Capture
Drawn
Scan
27
Generating still images Vector-Drawn
  • Vector-drawn - created from geometric objects
    such as lines, rectangles, ovals, polygons using
    mathematical formulas
  • e.g., RECT 0,0,200,300,RED,BLUE says
  • Draw a rectangle starting at 0,0 (upper left
    corner of screen) going 200 pixels horizontally
    right and 300 pixels downward, with a RED
    boundary and filled with BLUE.

28
Generating still images Vector
29
Generating still images Vector
  • The first popular vector-drawn images were for
    computer-aided design (CAD)
  • Such as AutoCAD, for aiding engineers and artists
    in creating complex renderings
  • Graphic artists designing for print media use
    vector-drawn objects because they put rectangles
    and Bezier curves on paper without jaggies,
    exploiting high resolution printers

30
Generating still images Vector
  • Macromedia Freehand, Corel Draw Adobe
    Illustrator are vector-drawing applications
  • Macromedia Flash puts vector-drawing on the Web
    with a plug-in

31
3D Object
  • 3D graphics tools, such as Macromedia Extreme3D,
    or Form-Z, typically extend vector-drawn graphics
    in 3 dimensions (x, y and z)

32
3D Object
  • A 3D scene consist of object that in turn contain
    many small elements, such as blocks, cylinders,
    spheres or cones (described in terms of vector
    graphics)
  • The more elements, the finer the objects
    resolution and smoothness.

33
3D Object
  • Objects as a whole have properties such as shape,
    color, texture, shading location.
  • A 3D application lets you model an objects
    shape, then render it completely.

34
3D Object
  • Modeling involves drawing a shape, such as a 2D
    letter, then extruding it or lathing it into a
    third dimension.
  • extruding extending its shape along a defined
    path
  • lathing rotating a profile of the shape around
    a defined axis

35
Extrude and Lathe
36
3D Object
  • Modeling also deals with lighting, setting a
    camera view to project shadows

37
3D Object
  • Rendering produces a final output of a scene
    and is more compute-intensive.

38
4.2 Colors
  • The tools we use to describe color are different
    when the color is printed than from when it is
    projected.
  • Projected color is additive.
  • Printed color is subtractive.

39
Additive Color
  • The additive reproduction process usually uses
    red, green and blue light to produce the other
    colors.
  • No light (or color) is black. All light (all
    colors) is white.

40
Subtractive Color
  • Subtractive color explains the theory of mixing
    paints, dyes, inks, and natural colorants to
    create colors which absorb some wavelengths of
    light and reflect others.

41
4.2 Colors
  • Color models
  • Different ways of representing information about
    color
  • Example
  • RGB
  • HSB
  • CMYK

42
HSB Model
  • Based on human perception of color, describe
    three fundamental properties of color
  • Hue
  • Saturation (or chroma)
  • Brightness - relative lightness or darkness of
    color, also measured as
  • There is no HSB mode for creating or editing
    images

43
HSB Model
  • Hue - color reflected from or transmitted through
    an object, measured on color wheel

44
HSB Model
  • Saturation (or chroma) - strength or purity of
    color ( of grey in proportion to hue)

45
HSB Model
  • Brightness - relative lightness or darkness of
    color, also measured as

0
50
100
Black white
46
RGB Model
  • Add red, green and blue to create colors, so it
    is an additive model.
  • Assigns an intensity value to each pixel ranging
    from 0 (black) to 255 (white)
  • A bright red color might have R 246, G 20, B 50

47
CMYK Model
  • Based on light-absorbing quality of ink printed
    on paper
  • As light is absorbed, part of the spectrum is
    absorbed and part is reflected back to eyes
  • Associated with printing called a subtractive
    model
  • Four channels Cyan (C ), magenta (M), yellow (Y)
    and black (K)
  • In theory, pure colors should produce black, but
    printing inks contain impurities, so this
    combination produces muddy brown
  • K is needed to produce pure black, hence CMYK is
    four-color process printing

48
4.2 Color
  • Color Gamut
  • Range of colors that a color system can display
    or print
  • Different models have different gamut (RGB has
    the smallest gamut, approximately)

49
4.2 Color
  • Color Channel
  • Photoshop shows information about color elements
    in different channels
  • E.g., RGB has at least three channels CMYK has
    at least four channels - at least, because
    Photoshop also permits Alpha channels for
    storing mask information
  • A mask lets part of an image be transparent so
    that other layers show through

50
4.3 Graphic Files Application 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

51
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)

52
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

53
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

54
Other Formats
  • BMP Bitmap File Format.
  • 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.

55
Other Formats
  • TGA Targa File Format.
  • 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.

56
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.

57
4.4 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.

58
4.4 Information Delivery
  • Graphics for information delivery include
  • Drawn images
  • Charts and graphs
  • Maps
  • Scenery
  • People

59
4.4 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.

60
4.4 Information Delivery
61
4.4 Information Delivery
62
4.4 Information Delivery
63
Summary
  • The computer generates still images as bitmaps
    and vector-drawn images.
  • Images can be incorporated in multimedia using
    clip arts, bitmap software, or by capturing,
    editing, or scanning images.
  • Creating 3-D images involves modeling, extruding,
    lathing, shading, and rendering.
  • Color is one of the most vital components of
    multimedia.
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