Scanner Resolution Detailed - Common Terms (1)

Second, the common term of resolution

Since the concept of resolution is not only used in scanning operations, it is widely used in the entire digital imaging field. Therefore, its connotation and representation are not single and fixed, and it is easy to cause confusion within a certain range. Define it. But in any case, it is important to understand the relevant technical terms before determining the best resolution.

The terms that are often heard about resolution are optical resolution, interpolation resolution, image resolution, display resolution, output resolution, printer resolution, and the like. In addition, other types of resolutions are either related to these concepts or are different names for these concepts.

1. Optical resolution

Optical resolution is an important parameter to measure the precision of the scanner's photosensitive device. That is, the actual number of light spots that can be captured per square inch of the optics of the scanner is the physical resolution of the scanner CCD and the true resolution of the scanner. Its value is divided by the number of pixels of the CCD divided by the number of scans. The value of the maximum horizontal sweep size obtained by the instrument. For example, a resolution of 1200dpi scanner, the optical part of the resolution only 400 ~ 600dpi. The resolution of the extended part (generated by hardware and software) is generated by computer analysis of the image and scientific filling of the blank part. For the scanner itself, the maximum resolution cannot be seen alone. The actual optical resolution better reflects the performance of the scanner.

2. Interpolation resolution

From the performance point of view, the interpolation resolution refers to the maximum resolution of the scanner, because it is obtained through the scanner driver, which is obtained through mathematical calculations, also called the highest resolution, software resolution. The principle is to insert additional information points between the two scanning points obtained by the optical resolution, so it will not add new details, only the average of the color and grayscale data between adjacent pixels, so that in Add a new pixel between them. For example, a scanner with an optical resolution of 600 dpi can achieve a maximum resolution of 9600 dpi by an interpolation algorithm. Moderate use of interpolation algorithm to improve the resolution, can increase the size of the image within a certain range, but will not bring about substantial improvement in image quality, because the image information obtained by interpolation is not directly obtained from the original image, with The nature of "false" is only of reference value to the scanner. For example, there is a 2 inch X 3 inch photo, scanned with an optical resolution 60dpi scanner with an accuracy of 600dpi, the resulting image size is 1200dpiXl800dpi The image is very clear at this time, because every point on the image is made of real photosensitive elements Acquired. Also with this photo, scanned with a scanner with an optical resolution of 300 dpi, because the optical resolution is up to 30 dpl so the resulting image size can only be 600 dpi X 900 dpi However, we need to get 1200 lang ixl800 dpi image to meet the requirements, had to pass the software Although the size of the 600dpiX 900dpi image was enlarged to 1200dpiXl800dpi, the resolution was greatly reduced.

From the above analysis, it can be seen that the resolution of the scanner is adjustable during use, and the adjustment method is performed by software (driver). If the set standard exceeds the device's optical resolution index, the driver will automatically perform interpolation operations on the excess to meet the user's needs.

3. Input resolution

The input resolution is the amount of information that the input device captures within each inch of wire. When the input device is a flatbed scanner, the input resolution refers to the scan resolution, which is measured in dots per inch (dpi). The scanning resolution is the resolution actually used by the scanner when scanning a document, not the output resolution set when scanning.

You can set a variety of different resolutions when scanning a job. If the size of the image output is already known when the image is scanned for the first time, the scanning resolution can be accurately selected so that it produces the exact amount of information needed, avoiding adding information or reducing information when processing the image later. The input resolution is only limited by the highest optical resolution or interpolation resolution of the scanning device.

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