MULTIMEDIA MULTIMEDIA TECHNOLOGYTECHNOLOGY

SMM 3001SMM 3001MEDIA - GRAPHICSMEDIA - GRAPHICS

In this chapterIn this chapter

how the computer creates, stores, how the computer creates, stores, and displays graphic imagesand displays graphic images

how painting programs allow the how painting programs allow the user to control computer graphic user to control computer graphic primitivesprimitives

the tools and features found in the tools and features found in drawing and illustration graphic drawing and illustration graphic applicationsapplications

how graphics software helps to how graphics software helps to automate creating 3-D images and automate creating 3-D images and animationsanimations

Graphic ImagesGraphic Images

for display) for display) graphic images graphic images are composed of are composed of pixelspixels

this type of this type of graphic is called graphic is called bit-mappedbit-mapped or or raster graphicsraster graphics

the image is the image is stored as a stored as a sequence of bits sequence of bits (a)(a) representing representing the pixel the pixel properties properties (b)(b)

Graphic ImagesGraphic Images

in most bit-in most bit-mapped mapped images, each images, each pixel requires a pixel requires a sequence of sequence of feature bitsfeature bits

the number of the number of bits needed bits needed corresponds to corresponds to the the bitplanes bitplanes for for the imagethe image

BitplaneBitplane

A single bit is not sufficient A single bit is not sufficient 4 bits (24 bits (244=16) are needed for =16) are needed for

each pixel to code specific value each pixel to code specific value for 16 possible shadesfor 16 possible shades

Therefore, 4 bitplanes is Therefore, 4 bitplanes is requiredrequired

Graphic ImagesGraphic Images

object-oriented object-oriented or or vector graphicsvector graphics treat the image as a collection of treat the image as a collection of graphic objects such as lines, graphic objects such as lines, curves, and figurescurves, and figures

vector graphics are vector graphics are resolution resolution independentindependent ( images don’t depend ( images don’t depend on the characteristics of a specific on the characteristics of a specific display device) and scalabledisplay device) and scalable

vector graphics are more easily vector graphics are more easily edited and often more compact in edited and often more compact in storagestorage

vector graphic images must often be vector graphic images must often be converted to bitmapped images for converted to bitmapped images for displaydisplay

Vector GraphicsVector Graphics

the image is the image is composed of composed of graphic objects graphic objects (lines, curves, (lines, curves, figures, etc.)figures, etc.)

each object is each object is defined by its defined by its graphic graphic propertiesproperties

these these properties may properties may be changed be changed and scaled and scaled easilyeasily

Vector GraphicsVector Graphics

each object each object occupies a occupies a separate layerseparate layer

layers may be layers may be moved, scaled, moved, scaled, and arranged in and arranged in different ordersdifferent orders

objects may be objects may be deleted and deleted and inserted easilyinserted easily

Graphics ApplicationsGraphics Applications

Bit-mapped Bit-mapped graphicsgraphics painting painting programsprograms

Vector graphicsVector graphics drawing drawing programsprograms illustration illustration programsprograms 3-D modeling and 3-D modeling and rendering programsrendering programs

Painting ProgramsPainting Programs

two-dimensional, bitmapped images/ two-dimensional, bitmapped images/ filesfiles

interface based on artwork metaphorinterface based on artwork metaphor image (canvas) painted with image (canvas) painted with

brushes, pencils, chalk, etc.brushes, pencils, chalk, etc. colors, patterns, and textures colors, patterns, and textures

selected from palettesselected from palettes image is divided into image is divided into foregroundforeground and and

backgroundbackground layers layers

Painting ProgramsPainting Programs

offer a variety of offer a variety of patterns, patterns, textures, and textures, and colorscolors

have assorted have assorted tools for tools for transforming transforming selected selected portions of the portions of the imageimage

have tools for have tools for creating pixel creating pixel masksmasks

Drawing ProgramsDrawing Programs

are simple vector graphic are simple vector graphic programsprograms

best-suited for basic illustrationsbest-suited for basic illustrations employ an artwork metaphor for employ an artwork metaphor for

the user interface like painting the user interface like painting programsprograms

an image is a set of graphic an image is a set of graphic objects that are created objects that are created individually and composed individually and composed togethertogether

Illustration ProgramsIllustration Programs

are also vector are also vector graphic programsgraphic programs

generate generate PostScript PostScript (scalable) output(scalable) output

have extensive have extensive tools, effects, and tools, effects, and featuresfeatures

used for used for professional professional applicationsapplications

3-D Graphics3-D Graphics

3-D graphic programs automate 3-D graphic programs automate creating images with creating images with perspective projection and perspective projection and special effects of lighting and special effects of lighting and shadingshading

these applications employ either these applications employ either volume-basedvolume-based or or surface-basedsurface-based 3-D graphics3-D graphics

3-D Graphics3-D Graphics

Volume-basedVolume-based 3-D image is 3-D image is

defined by voxels defined by voxels (volume elements)(volume elements) 3-D picture 3-D picture

elements having elements having location, color, location, color, intensity, intensity, transparency, transparency, opacityopacity

used for scientific used for scientific visualization and visualization and modelingmodeling

Surface-basedSurface-based 3-D image is 3-D image is

composed of objects composed of objects defined in 3 defined in 3 dimensionsdimensions

regular shapes form regular shapes form the facets or the facets or components of each components of each objectobject

rendering involves rendering involves adding texture, adding texture, shading, and lighting shading, and lighting effectseffects

Surface-based 3-D GraphicsSurface-based 3-D Graphics

3-D image is 3-D image is created in stagescreated in stages model descriptionmodel description

each object is each object is defined in 3 defined in 3 dimensionsdimensions

scene descriptionscene description objects are objects are

placed in sceneplaced in scene renderingrendering

Process of Process of creating the creating the illusion of illusion of photorealismphotorealism

perspective, and perspective, and special effects special effects addedadded

Surface-based 3-D GraphicsSurface-based 3-D Graphics

SOLID MODELING SOLID MODELING - objects are - objects are composed of simple 3-D regular composed of simple 3-D regular solids used as primitivesolids used as primitive

POLYGON-SURFACE MODELING POLYGON-SURFACE MODELING --objects are composed of facets objects are composed of facets shaped from polygonsshaped from polygons

WIREFRAME MODELING WIREFRAME MODELING - objects - objects are composed of facets including are composed of facets including parametric curved shapesparametric curved shapes Supported by most applicationsSupported by most applications

Solid ModellingSolid Modelling

Polygon Surface ModellingPolygon Surface Modelling

Wireframe ModellingWireframe Modelling

Surface-based 3-D GraphicsSurface-based 3-D GraphicsRendering techniquesRendering techniques Lambert shadingLambert shading

Also known as flat Also known as flat shadingshading

Gouraud shadingGouraud shading Take account the lighting Take account the lighting

effects on the effects on the surrounding surfacessurrounding surfaces

Phong shadingPhong shading Recalculate the illumination Recalculate the illumination

modelmodel

Ray-tracingRay-tracing Take account of the light rays Take account of the light rays

that are reflected from the that are reflected from the objectobject

Flat vs Gouraud shadingFlat vs Gouraud shading

Phong ShadingPhong Shading

Ray TracingRay Tracing

Texture MappingTexture Mapping Another common technique for determining Another common technique for determining

the appearance of a polygon is to use the appearance of a polygon is to use texture mappingtexture mapping..

Think of texture mapping like wrapping a Think of texture mapping like wrapping a present. Each side of the box you are present. Each side of the box you are wrapping is a blank polygon. You could wrapping is a blank polygon. You could paint the box, but it would be very difficult paint the box, but it would be very difficult to make it match all the designs on the to make it match all the designs on the wrapping paper.wrapping paper.

However, if you take the wrapping paper However, if you take the wrapping paper and tightly cover the box with it, you have and tightly cover the box with it, you have completely transformed the box with just a completely transformed the box with just a little effort. little effort.

Texture mapping works the same way. Texture mapping works the same way. Mapping requires the use of another Mapping requires the use of another image. This other image essentially is image. This other image essentially is stretched over the object like a skin.stretched over the object like a skin.

Texture MappingTexture Mapping

AnimationAnimation

animations are composed of animations are composed of individual graphic images called individual graphic images called framesframes

Professional-quality animations Professional-quality animations employ rates of 24 fps and higheremploy rates of 24 fps and higher

frames are displayed at a rate fast frames are displayed at a rate fast enough to be perceived as enough to be perceived as continuous motioncontinuous motion

animation software help to automate animation software help to automate the creation of animated graphicsthe creation of animated graphics

AnimationAnimation

In-betweening In-betweening automates the automates the creation of animated creation of animated sequencessequences

key frames are key frames are defined for starting defined for starting and stopping and stopping positionspositions

the software the software calculates the calculates the incremental framesincremental frames