Epson Stylus Scan 2500 Pro_Technical-Brief-(Scanners)_pdf

Scanner Technical Brief—Page 1 6/07 This technical brief provides detailed information on the Image Quality, Performance, and Flexibility of Epson Scanners. Image Quality—Factors affecting image quality When comparing scanners, hardware resolution and color pixel depth are two features often used to gauge image quality. These two features are important, but there are a number of factors that determine image quality in a scanner, such as the following: (Many of these elements will be discussed in detail in upcoming sections of this document.) The Epson Expression ® and GT series scanners are Epson’s professional series scanners designed for excel- lence with respect to image quality, speed, usability, versatility, and durability. These scanners include the highest quality components. The Epson Perfection ® series scanners are designed for home and entry-level corporate and graphics arts users, and are designed with the highest quality components in their price class. Precision stepper motor for high quality sub-scan resolution Dynamic range control Type of lamp system used Optic system Optical resolution and color bit depth Quality of the Analog to Digital con- verter (ADC); Epson scanners have optimum performance for minimal noise and tight color registration. Type of focus method Color vs. monochrome CCD Image Quality—Resolution A scanner’s resolution determines the amount of data that is read by the scanner. As resolution increases, so does the file size. Resolution is measured in a variety of ways. 1. Optical resolution: This is the actual number of pixels read by the CCD (Charge Coupled Device), which measures the intensity of the light that is reflected from the image to be scanned, and converts it to an analog voltage. If a scanner has a resolution of 600 x 2400 dpi, its optical resolution is 600 dpi, which means that it can resolve 600 bits of data per inch. 2. Hardware resolution: Using a precision stepper motor to double-step or quadruple-step the carriage, the scanner’s sub-scanner resolution can be increased. For example, a scanner can have an optical resolution of 1200 dpi, but a hardware resolution of 1200 x 2400 dpi (because it double-steps the carriage to increase the vertical resolution). 2 1200 dpi
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