Scanners

Scanner manufacturers represent the fixed, optical resolution of their products with two numbers: 1200 x 2400 dpi for example.

In this case 1200 would be the number of sensors that are positioned horizontally in the scanner head and 2400 would be the number of steps the carriage motor can take as it travels one inch down the film or document being scanned.

When they claim that their scanner has a maximum resolution of 9600 dpi they are describing the amount of information the scanner software can interpolate, or fake.

Digital image pixels that are created by scanners can be many different sizes depending on how many slices, or "samples," the scanner divides the image into. For example, a 300 sample per inch (spi) pixel is 1/300th of an inch wide. A 1 spi pixel is one full inch wide!

Scanners usually refer to the image pixels they create as dots per inch or dpi because, just like camera sensors, the scanner is recording visual information that is intended to be rendered as dots of pigment on the surface of photographs created by an ink jet printer.

One other measure of a scanner's quality is its density range. This describes the amount of contrast the scanner can record and the higher this number the greater the scanner's ability to render detail in the shadow areas. Density range numbers above 3.2 are very good.

Get Paid to Take Digital Photos

Get Paid to Take Digital Photos

Reasonable care has been taken to ensure that the information presented in this book isĀ  accurate. However, the reader should understand that the information provided does not constitute legal, medical or professional advice of any kind.

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