TAILIEUCHUNG - How to Do Everything With Your Scanner- P26

How to Do Everything With Your Scanner- P26: My thanks to the terrifically creative and knowledgeable staff at Osborne, particularly acquisitions editor Megg Bonar and acquisitions coordinator Alissa Larson for their responsiveness and flexibility. Special thanks to technical editor Steve Bain, not only for his insight and attentiveness to accuracy, but also for actively coming up with many ideas for content. | CHAPTER 6 Scanning Techniques for Different Types of Images 109 Bitmap Versus Vector Images Line art can be categorized as either a bitmap or vector image. A bitmap image sometimes called a raster is created from differently colored rows of pixels. Figures 6-6 and 6-7 provide an illustration of how a bitmap image works. The image that appears on your computer monitor is a bitmap. A vector image is constructed using complex mathematical formulas that describe shape color and placement. A vector image doesn t consist of dots. It s made of curves lines and other shapes defined with mathematical precision. It s the job of the graphic artist to combine the shapes to get the desired image. FIGURE 6-6 A bitmap image at the resolution it s normally viewed at 110 How to Do Everything with Your Scanner FIGURE 6-7 An enlarged image showing the rows of pixels that make up the image You can convert a vector file into a bitmap file. Doing so will save some space because vector files are generally much smaller than bitmap files. Vector files are often used for line art but aren t appropriate for reproducing complex images such as photos. On the other hand it s very difficult to convert a bitmap file to a vector file but most likely you won t want to. Vector files are often used for line art because they are easier to alter than bitmap files. Bitmap files can appear jagged if you enlarge them or fuzzy if you shrink them while vector files are easy to resize because the mathematical proportions that make up the various shapes are precisely changed. CHAPTER 6 Scanning Techniques for Different Types of Images 111 Produce High-Quality Grayscale Images A grayscale image is one that s made of continuous shades of gray ranging from pure black to pure white. The photos of Ansel Adams are good examples of grayscale. Adams was famous for his ability to capture subtle detail and shadows. This effect is achieved by reproducing hundreds of different shades of gray. The more shades of gray that

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