multimedia technology smm 3001 media - graphics. in this chapter how the computer creates, stores,...
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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
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
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.
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