How to Do Everything With Your Scanner- P26 pptx

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.. If you’re planning on printing the image, scan at a reso

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

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

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 can be produced, the more detailed a grayscale image Figure 6-8 is an example of an image captured using a setting that reproduces 256 shades of gray

When scanning a grayscale image, use the grayscale setting on your scanner If you’re planning on printing the image, scan at a resolution setting of 150 to 300 spi (or samples per inch) Opt for something at the higher end of that range if you’re planning on enlarging the photo If you plan to view the image only on the Web, scan

at a lower resolution of 72 to 75 spi, or 96 dpi A higher resolution will increase file size considerably, without producing a noticeably better result on screen

Capture Vibrant Color Images

Today’s scanners and printers allow you to create vivid color prints To scan color images successfully, you need to pay attention to both the resolution and color-capture settings of your printer

Rules of thumb for color resolution are similar to those for grayscale If you’re planning on printing a color photo, scan at a resolution setting of 150 to 300 spi If you’re planning to enlarge the photo or reproduce it in a publication, don’t scan at a lower resolution than 300 spi For Web images, scan at a resolution of 72 to 75 spi, or

96 dpi A higher resolution will increase file size, without producing a better result on screen

Your scanner might offer several different capture settings for color photos, including true color, 256 color, and spot color All these settings serve distinct color-capture functions

Maximize Quality with the True-Color Setting

This setting is capable of producing 16,777,216 colors, referred to as 16.7 million colors This is sometimes referred to as 24-bit color Of course, the human eye cannot discern anywhere near 16 million colors, and this option might result in unnecessarily large files Use this format only when you need to store as much image data as possible

Optimize Your 256-Color Images

The 256-color setting, sometimes referred to as 8-bit color, allows you to capture up

to 256 colors Your scanner might have the following selections under this choice:

Web Palette This setting uses a 216-color format that can be displayed by all Web browser software Web browser software is the program on your computer that allows you to view images sent over the Internet

System Palette This option uses the 240 colors used by the Windows program It’s meant for images that will be displayed using a Windows-based program

Optimized Palette This option creates a set of the best possible 256 colors to represent your image to its best advantage It selects from the 16,777,216 true colors that are available This option is often associated with GIF or other fixed-palette image formats restricted to 256 colors By optimizing an image’s fixed-palette colors, only the minimum number of colors needed to reproduce the image are stored in the palette of the image file For example, if only two are required, only two are stored

Save File Space with the Spot-Color Option

The spot-color setting scans a limited range of colors Solid colors are represented as single color data, rather than a gradation of hues Spot color is great for scanning logos and graphics with limited color

Working with Half-Tone Images

Laser printers and many commercial printing presses reproduce images such as grayscale and color photographs (sometimes called continuous-toned images) using a technique called half-toning

Why You Need to Know about Half-Toning

Although half-toning can be done during the scanning process, it’s usually a function performed by your printer Most color printers have sophisticated drivers that perform the process; however, you need to be aware that image data is reordered and discarded

in the process of creating a half-tone (printable) image from a continuous-toned color photograph or grayscale piece As image detail and complexity increases, there might

be a trade off between the amount of color data that can be saved and the resolution of the photo

Images are divided into half-tone cells, each of which contains an appropriate number

of color dots The more dots than can be stored per cell, the more color combinations that can be produced As you use printer dots to create color combinations, however, you decrease the amount of printer dots available to re-create other image detail Thus, the increased color quality can decrease the overall resolution of the image, making it