Are you getting confused of the resolution requirements for scanning? Of the “high-res” your scanner offers? And do you really need it or will it just make your work slower?
Whenever we scan an image, we are very much particular with the resolution and details that we get. Our ultimate goal is to have the exact copy of the original image. Not all scanners provide us with what we want. Although there are those which seem to give us a lot better than what we need.
A standard resolution for an image should be 300dpi (dot-per-inch) and 400dpi for images containing text. However, there are scanners that offer you greater resolutions ranging from at least 3,200 dpi up to 6,200 or 9000 dpi. But do we really need resolutions this high?
A flatbed scanner is a type of scanner that converts printed materials into digital image. It is made up of charged coupled devices or CCD. CCD is a light sensitive integrated circuit that is mounted in a stationary row. These CCDs allows light reflected from a flat art to pass over and registers presence and absence of light. So the pixel is produced electronically. Pixel, from the words “picture element”, is the basic unit of programmable color in a computer image.
CCDs are mounted in a single row so they reflected one row of the flat art at a time. The task is repeated until the image is completely built. The resolution is controlled horizontally by the distance between each CCD and vertically by the speed of the light bar and mirror that moves along the length of the flat art. This means that, if you want a better resolution the scanner must have more CCDs and slower light bar.
Although many scanner manufacturers claim that they have the most powerful scanner that offers the highest resolution, it is said that the highest resolution is limited to only 600 spots per linear inch. There’s a way in proving this theory. Think of scanning a 600x1200 dpi. If measurement is based on the X and Y (horizontal and vertical) of the square inch, the output would either be a series of squares with some blank spots, or a square with overlapping spots. For non-uniform resolution such as these, scanners perform interpolation. Interpolation is a process whereby a software or firmware is needed to produce an extra pixel by sampling two pixels.
Grey-scale scanners and color scanners are different from flatbed scanners. They all contain CCDs, but CCDs in grey-scale and color scanners can differentiate between levels of light falling on them.
The bottom line here is that why do we have to consume a large amount of our computer’s memory if we can have the exact number of pixels without compromising the quality. Not only that, we can also minimize the time spent for interpreting the data including those that we do not use.
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