Adobe Illustrator 8.0

"A Vector Drawing Program"

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(Vector or Object-based Programs)

With Illustrator and other vector-based applications you are working in a world of shapes. Vector images, also called object-oriented or draw images, are defined mathematically as a series of points joined by lines. Graphical elements in a vector file are called objects. Each object is a self-contained entity with properties such as color, shape, outline, size, and position on the screen, included in its vector vs. raster imagesdefinition. Since each object is a self-contained entity, you can move and change its properties over and over again while maintaining its original clarity and crispness, and without affecting other objects in the illustration. These characteristics make vector-based programs ideal for illustration and 3D modeling, where the design process often requires individual objects to be created and manipulated.

Vector-based drawings are resolution independent. You can easily resize vector images to a thumbnail sketch or a billboard-sized graphic, and you can print in any resolution. A circle can be drawn in 72 dpi, 300 dpi, or 3,000 dpi. As the resolution of the output device increases, the quality of the picture increases--which is not true for bitmapped graphics. Vector images don't become grainy when resized or lose detail and proportion. Smooth curves are easy to define in vector-based programs and they retain their smoothness and continuity even when enlarged.You can change vector-based images into bitmap formats when needed.

(Raster or Bitmap-based Programs)

With Photoshop and other bitmap-based applications you are working in a world of color and photographic quality images. Bitmap images, also called raster or paint images, are made of individual dots called pixels (picture elements) that are arranged and colored differently to form a pattern. When you zoom in, you can see the individual squares that make up the total image. However, the color and shape of a bitmap image appear continuous when viewed from a greater distance. Because each pixel is colored individually, you can easily work with photographs with 16,000 colors and can create photorealistic effects such as shadowing and intensifying color by manipulating select areas, one pixel at a time. Bitmap programs are used to retouch photographs, editing images and video files and creating original artwork. Subtle changes to photos can be made: adjusting the lighting, sharpening the focus, and removing scratches. Drastic changes such as removing people and things, swapping details between images, adding text and objects, adjusting color, colorizing black-and-white and grayscale images, splicing movies, and applying unique combinations of special effects. Bitmap programs are used to create images with GIF and JPEG formats as needed for the Web.

But the disadvantage of bitmap images comes when you want to change the size, shape, or resolution of the picture. Increasing the size of a bitmap has the effect of increasing individual pixels, making lines and shapes appear jagged. Reducing the size of a bitmap also distorts the original image because pixels are removed to reduce the overall image size. Also, because a bitmap image is created as a collection of arranged pixels, its parts cannot be manipulated individually. Because you cannot easily change the size of bitmap images, the quality of your output is dependent on the decisions you make about resolution early in the process. Bitmap images look best when printed at their original size and proportions.


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