Understanding Contents

• Vector Graphic Images • Spline Curves • More About Bézier Curves • Vector Graphic Output Options • Metafile Graphic Images • Metafile Graphic Output Options

Vector Graphic Images

• Composed of mathematically defined lines and curves called vectors and are device independent, which means they don’t have a fixed resolution. • Figures can be moved, resized or rotated as an independent object as the figure definition is mathematically retained. • Best for type and other shapes that require crisp, clear boundaries. • Typically produced by illustration/drawing/CAD software such as , Adobe Flash, Corel DRAW, AutoCAD, Turbocad etc. or by scanning artwork etc and tracing or vectorising.

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Vector Graphic Example Spline Curves

• Spline: A line defined by control points. • Types: • B-Spline: Control points with equal weight that usually are away from curve. • Bézier: Control points always on the curve. Handles on control points for modifying curve. • NURBS (Non Uniform Rational B-Spline): Control points away from curve with weights to control curve. Spline Curves

Spline Curves More About Bézier Curves

• Developed by Pierre Bézier (a Renault automotive engineer) in 1960s as way to mathematically describe smooth contours on a car surface. • Historically complex lines either required arduous calculations (in mathematical drawings), or were just drawn by hand (in visual arts and design). • In the 20th century this deficiency proved to be a real obstacle, especially in industrial design, where complex curved lines and surfaces must be precisely defined so as to be uniformly reproduced in metal or plastic. More About Bézier Curves

• Bezier curves (after their inventor), are now familiar to any user of a vector drawing program. The Pen Tool in Photoshop and Illustrator is the classic Bezier curve tool. • The most commonly used Bezier curves are fully defined by four points: two endpoints and two control points that do not lie on the curve itself but define its shape. More About Bézier Curves

Bezier curve examples

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• Some typical vector file formats are: • AI (Adobe Illustrator) • CDR (Corel DRAW) • DWG (AutoCAD) • DXF (Drawing Exchange Format): Developed by AutoCAD as a CAD file exchange format. • SWF (Shockwave Flash Format) • EPS (Encapsulated PostScript

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• Metafiles are a compromise between the photo- realistic qualities of a image and the scalability of a vector image. • They are files that may contain both bitmap and vector data. • It must be remembered that many vector based file formats such as the Illustrator and Flash format also support bitmap data.

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• Common File Formats: • EPS (Encapsulated PostScript): File format supported by most illustration and page-layout programs, and used to be the preferred format for these applications. When an EPS file is loaded into an image editing package like Photoshop you will be prompted as to the resolution you would like to rasterize the file at. • (PDF) Portable Document Format: A flexible, cross-platform, cross- application file format. Based on the PostScript imaging model, PDF files accurately display and preserve fonts, page layouts, and both vector and bitmap graphics. In addition, PDF files can contain electronic document search and navigation features such as electronic links. This has largely replaced the EPS format in many instances like an EPS file when it is loaded into an image editing package like Photoshop you will be prompted as to the resolution you would like to rasterize the file at.. • WMF ()

Return to contents References

• Illustrator help files • Photoshop help files • http://www.webreference.com/dlab/9902/bezier.html • 3D Graphics & Animation by Mark Giambruno