Graphics: Creating Images Chapter 8, Exploring the Digital Domain

In this chapter... how the computer creates, stores, and displays images how painting programs allow the user to control graphic primitives the features that are found in drawing and illustration programs how software helps to automate creating 3-D projections and animations You will learn about

Graphic images (for display) graphic images are composed of pixels this type of graphic is called bit-mapped or raster graphics the image is stored as a sequence of bits (bottom) representing the pixel properties (top)

Graphic Images in most bit-mapped images, each pixel requires a sequence of feature bits the number of bits needed corresponds to the bitplanes for the image

Graphic Images vector graphics or object-oriented treat the image as a collection of graphic objects such as lines, curves, and figures defined mathematically vector graphics are resolution independent and scalable vector graphics are more easily edited and often more compact in storage vector graphic images must often be converted to bitmapped images for display

Graphic Applications painting programs drawing programs illustration programs 3-D modeling and rendering programs Bit-mapped graphicsVector graphics

Storing Graphic Images TIFFs, GIFs, PNGs, BMPs, WMFs, and PICTs are image file formats used to store graphic images too. PCX, CGM, EPS, EMF, DXF, SVG, and QuickTime are also popular formats

Storing Graphic Images PCX is the native file format for PC Paintbrush and other Windows apps CGM (computer graphics metafile) is an open-source metafile format EPS (encapsulated PostScript) is a standard metafile format for professional printing applications

Storing Graphic Images EMF (enhanced metafile format) is Window’s successor to WMF DXF (drawing exchange format) is AutoCad’s 3-D file format SVG (scalable vector graphics) is an open-source format based on XML QuickTime is used for storing video and animations

Painting Programs two-dimensional, bitmapped images/ files interface based on artwork metaphor image (canvas) painted with brushes, pencils, chalk, etc. colors, patterns, and textures selected from palettes image is divided into foreground and background layers

Painting Programs tools are based on selecting areas of pixels for editing masks can be used to separate sections of the image multiple layers may also be used

Painting Programs offer a variety of patterns, textures, and colors have assorted tools for transforming selected portions of the image have tools for creating pixel masks

Vector Graphics the image is composed of graphic objects (lines, curves, figures, etc.) each object is defined by its graphic properties these properties may be changed and scaled easily

Vector Graphics employ anti-aliasing or smoothing to reduce jagged artifacts are easily scalable for a variety of resolutions and output devices

Vector Graphics incorporate parametric curves-- based on mathematical plotting for examples, Bezier and B-spline curves

Vector Graphics each object occupies a separate layer layers may be moved, scaled, and arranged in different orders objects may be deleted and inserted easily

Drawing Programs are simple vector graphic programs best-suited for basic illustrations employ an artwork metaphor for the user interface like painting programs an image is a set of graphic objects that are created individually and composed together

Illustration Programs are also vector graphic programs generate PostScript (scalable) output have extensive tools, effects, and features used for professional applications

3-D Graphics 3-D graphic programs automate creating images with perspective projection and special effects of lighting and shading these applications employ either volume-based or surface-based 3-D graphics

3-D Graphics 3-D image is defined by voxels 3-D picture elements having location, color, intensity, transparency, opacity used for scientific visualization and modeling 3-D image is composed of objects defined in 3 dimensions regular shapes form the facets or components of each object rendering involves adding texture, shading, and lighting effects volume-basedsurface-based

Surface-based 3-D Graphics model description each object is defined in 3 dimensions scene description objects are placed in scene rendering perspective, and special effects added 3-D image is created in stages

Surface-based 3-D Graphics SOLID MODELING--objects are composed of simple 3-D regular solids used as primitive POLYGON-SURFACE MODELING--objects are composed of facets shaped from polygons WIREFRAME MODELING--objects are composed of facets including parametric curved shapes

Surface-based 3-D Graphics Lambert shading Gouraud shading Phong shading Ray-tracing RENDERING TECHNIQUES

Animation animations are composed of individual graphic images called frames frames are displayed at a rate fast enough to be perceived as continuous motion animation software help to automate the creation of animated graphics

Animation In-betweening automates the creation of animated sequences key frames are defined for starting and stopping positions the software calculates the incremental frames