Brief Overview of the Digital Imaging Process
| A. | Copy Machine Comparison | |
| 1. Flatbed scanners are built like copy machines, in that, they have a glass plate under a lid, with a moving light that scans across under it. 2. Scanners, though, have much more control…instead of printing a piece of paper out, scanners create an image in the computer’s memory which can be saved, manipulated, faxed, emailed, etc |
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B. |
Operating the Scanner 1. We use software to operate the scanner (Photoshop, Fireworks, Acrobat, HP PrecisionScan Pro). |
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| C. | What “Scan” Actually Means... | |
| 1. CCD (Charge Coupled Device) – These units use an optical lens, often like a fine camera lens, and a system of mirrors to focus the bed image on the CCD cells. The CCD is an analog device, which uses a converter chip to talk to the computer. 2. Resolution – The scanner actually scans one horizontal row of pixels at a time, moving the scan-line down the page with a carriage motor. (Example – A 600 dpi scanner takes 600 color samples per inch horizontally from the width being scanned.) |
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| D. | Types of Scan | |
| 1. RGB or “Millions of Color” – 24 bit color mode, which scans three color samples per pixel, the combination of which is the one resulting color from 16.7 million possible colors. 2. Gray Scale or “Gray Mode” – 256 shades of gray, 0 to 256; one shade of gray per pixel 3. Black and White – This is 1 bit data from 2 possible colors, white or black |
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