The scanner is a very flexible image acquisition device. To determine which scanner is best for you, a good way is to establish the type of document to be processed and how to obtain the image file data.
Is the manuscript flat or three-dimensional? Can a flat original be bent? How is the original size? What is the magnification of the acquired image? Is the image carrier media a transparent material (film) or a reflective material (paper)? Is it a line image or a continuous tone image? Is the original a halftone print? To remove halftone dots in halftone originals, not all image acquisition devices can do it.
Some other factors also affect the choice of scanner, including ease of use, versatility, software features, durability, reliability, productivity, and manufacturer's credibility. If you want to scan color transparencies, the scanner is required to have the ability to recognize large-scale gradation changes, especially dark areas. If the interface design of the software is excellent, it may provide stronger functions, for example, directly scanning the color negative film into a positive film form; during the scanning, the color separation process of converting the RGB signal to the CMYK signal may be performed.
If only the printed text is to be entered into the computer, a hand-held scanner with OCR (Optical Character Recognition) software is sufficient. A simple black and white platform scanner scans grayscale images or line images. If the scanner is required to have the ability to enhance the rich details of the color image without deteriorating the image quality, the scanning software needs to be able to analyze the more abundant pixels in the image to distinguish between the two. Different changes. This process requires a professional platform or roller scanner with a very high resolution.
The resolution of the input device is in units of ppi (number of dots per inch of length), and the maximum resolution of the output device is the number of recorded dots (dpi) per inch that the device can print or record. The true optical resolution of the CCD input device is determined by the number of CCD cells per inch length and the optical system. In some cases, the resolution of the image may be increased by software using an interpolation algorithm compared to the actual optical resolution of the input device. This technique can avoid the human eye can distinguish each pixel point very clearly during the amplification process to produce a mosaic effect. However, using this technique will not get more image details.
Types of scanners Platform scanners: Platform-based scanners based on CCD (photocoupler) are the most popular image capture devices for desktop publishing and specialized prepress processing. They are generally directly manipulated by image editing software. This kind of scanner generally has low requirements for the operator, because the driver software itself can automatically determine the color balance and density range of the image.
There are many types of flatbed scanners, ranging from low-cost black-and-white scanners to high-quality, professional-quality color scanners. The high-quality platform scanner scans both reflective and transmissive originals. However, for mid-range scanners, an optical device is required for the translucent document.
Professional platform scanners are generally cheaper than conventional roller scanners, although they give a similar quality of scan. Another advantage of the professional scanner is that it can also scan hard image originals.
Transmitted document scanners: These CCD-based devices are mainly used for high-resolution scanning of transmission images. Widely used in service departments, trade centers, newspapers and magazines. When the transmissive film size is not limited to 35mm, there are often standard film manuscript frames that can be used. Some models of scanners support the ability to automatically load and batch scan a transmitted document. Focusing, color control, and image density calibration are sometimes automated.
Roller Scanners: The optoelectronic components that distinguish the RGB signals used by the roller scanner are photomultiplier tubes. This optoelectronic component can produce high-quality scanning results. The early roller scanners are very complex. To fully realize their potential, operators are required to have skilled operating skills. This kind of scanner has always been the most expensive image acquisition device on the market, but with the development and popularity of desktop publishing technology, its price has begun to decline. Only very soft originals can be placed on a roller scanner for scanning, and this scanning process is time consuming. Regardless of negative or positive film, either transmissive or reflective documents are suitable for this type of scanner.
Hand-held scanners: These low-cost CCD devices manually scan black and white or colored flat originals. They are not specifically designed for transparencies. The largest format is generally smaller than A4 format. Although some hand-held scanners have a scanning resolution of 800 ppi, the scanning results are generally not satisfactory. The use of such scanners, including OCR recognition, and for the rapid capture of continuous tone images illustrating the positioning relationship when forming a full-page layout design idea. (To be continued)
Is the manuscript flat or three-dimensional? Can a flat original be bent? How is the original size? What is the magnification of the acquired image? Is the image carrier media a transparent material (film) or a reflective material (paper)? Is it a line image or a continuous tone image? Is the original a halftone print? To remove halftone dots in halftone originals, not all image acquisition devices can do it.
Some other factors also affect the choice of scanner, including ease of use, versatility, software features, durability, reliability, productivity, and manufacturer's credibility. If you want to scan color transparencies, the scanner is required to have the ability to recognize large-scale gradation changes, especially dark areas. If the interface design of the software is excellent, it may provide stronger functions, for example, directly scanning the color negative film into a positive film form; during the scanning, the color separation process of converting the RGB signal to the CMYK signal may be performed.
If only the printed text is to be entered into the computer, a hand-held scanner with OCR (Optical Character Recognition) software is sufficient. A simple black and white platform scanner scans grayscale images or line images. If the scanner is required to have the ability to enhance the rich details of the color image without deteriorating the image quality, the scanning software needs to be able to analyze the more abundant pixels in the image to distinguish between the two. Different changes. This process requires a professional platform or roller scanner with a very high resolution.
The resolution of the input device is in units of ppi (number of dots per inch of length), and the maximum resolution of the output device is the number of recorded dots (dpi) per inch that the device can print or record. The true optical resolution of the CCD input device is determined by the number of CCD cells per inch length and the optical system. In some cases, the resolution of the image may be increased by software using an interpolation algorithm compared to the actual optical resolution of the input device. This technique can avoid the human eye can distinguish each pixel point very clearly during the amplification process to produce a mosaic effect. However, using this technique will not get more image details.
Types of scanners Platform scanners: Platform-based scanners based on CCD (photocoupler) are the most popular image capture devices for desktop publishing and specialized prepress processing. They are generally directly manipulated by image editing software. This kind of scanner generally has low requirements for the operator, because the driver software itself can automatically determine the color balance and density range of the image.
There are many types of flatbed scanners, ranging from low-cost black-and-white scanners to high-quality, professional-quality color scanners. The high-quality platform scanner scans both reflective and transmissive originals. However, for mid-range scanners, an optical device is required for the translucent document.
Professional platform scanners are generally cheaper than conventional roller scanners, although they give a similar quality of scan. Another advantage of the professional scanner is that it can also scan hard image originals.
Transmitted document scanners: These CCD-based devices are mainly used for high-resolution scanning of transmission images. Widely used in service departments, trade centers, newspapers and magazines. When the transmissive film size is not limited to 35mm, there are often standard film manuscript frames that can be used. Some models of scanners support the ability to automatically load and batch scan a transmitted document. Focusing, color control, and image density calibration are sometimes automated.
Roller Scanners: The optoelectronic components that distinguish the RGB signals used by the roller scanner are photomultiplier tubes. This optoelectronic component can produce high-quality scanning results. The early roller scanners are very complex. To fully realize their potential, operators are required to have skilled operating skills. This kind of scanner has always been the most expensive image acquisition device on the market, but with the development and popularity of desktop publishing technology, its price has begun to decline. Only very soft originals can be placed on a roller scanner for scanning, and this scanning process is time consuming. Regardless of negative or positive film, either transmissive or reflective documents are suitable for this type of scanner.
Hand-held scanners: These low-cost CCD devices manually scan black and white or colored flat originals. They are not specifically designed for transparencies. The largest format is generally smaller than A4 format. Although some hand-held scanners have a scanning resolution of 800 ppi, the scanning results are generally not satisfactory. The use of such scanners, including OCR recognition, and for the rapid capture of continuous tone images illustrating the positioning relationship when forming a full-page layout design idea. (To be continued)
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