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Scanning Help - Resolution
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1: What is Image Resolution? |
Digital Image Resolution is an important concept to understand when scanning and manipulating images. A Digital Image is composed of an array of picture elements or "pixels." Each pixel represents a single color and value. The computer arranges the pixels to create the illusion of a continous image, in a manner similar to that of a television screen or a Pointillist painting. Image Resolution simply refers to the number of pixels per square inch. This measurement is commonly called "dots per inch," or "dpi." In most cases, higher resolution results in better image quality.
Remember, however, that final image quality is limited by the quality of your image source. While image resolution can always be reduced after scanning, raising resolution once the image has been scanned will not improve image quality!
Your ideal resolution depends on how you intend to use your digital image. The resolution of a computer monitor is 72 dpi. Accordingly, 72 dpi is the ideal resolution for iamges that will be seen exclusively on a computer monitor. While a 72 dpi image may look great on a computer moniter, its relatively low resolution becomes evident once it is printed. Most laserjet and inkjet printers print at a resolution of 300 dpi, which is a good resolution for most image applications, such as desktop publishing.
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3: Does resolution affect file size? |
Yes. Image Resolution is perhaps the most important determinant of file size. Since resolution measures dots per square inch, file size is proportional to the square of Image Resolution. For instance, the file size of a 600 dpi image is 9 times that of a 200 dpi image.