Camera Type Scanners Digital Cameras: Some CCD digital cameras are used only for recording data and cannot record conventional film. The rest of the digital cameras are the addition of a camera back to a standard film camera. Digital cameras record digital information on removable disks. The capacity of the disk and the number of cells of the CCD array limit the resolution of the acquired image.
Digital cameras are ideally suited for use in the press industry because digital images captured can be immediately transmitted via modem or satellite for newspaper publishing. A standard film camera with a camera back can obtain high-definition images and transmit the data via cable to a fast hard disk. The RGB primary colors can be scanned at the same time or in three scans, requiring the camera to be mounted on a stable tripod and not allowing the selected subject to move. Although the camera with a back plane is more suitable for acquiring 3-D object images, it can be used like a platform scanner.
Video Camera: Moving a continuous image or a separate still image can be captured by a computer-based frame capture system such as a CCD video camera or video tape. Multimedia playback software can edit and use these moving images, although too large data limits the quality, size, and recording time of the images. If a video clip only records an important event, the resampling process may be used to increase the resolution of each frame so that these frames can be output with reasonable quality effects.
Photosensitive technologies Photomultiplier tubes and optocouplers both convert different brightness changes into continuous changes or analog voltage changes. Using an analog-to-digital converter's sampling process, this continuous change can be converted to a specified number of stages. The purity of a tiny analog signal is easily affected by noise generated from electronic interference or incorrect signals. Therefore, good signal-to-noise ratio is a critical issue when designing photosensors and related circuits. Most light sources and analog electronics require a certain amount of time to reach a stable operating temperature and conditions. Therefore, it is recommended that you turn on the scanner and wait a few minutes before starting the scan.
Here are two technical features of PMT and CCD:
PMT sensor: The conventional roller scanner uses a xenon light source or a tungsten halogen light source. Both of these light sources can be focused on a small area of ​​the manuscript by means of an optical fiber and a condenser lens. The source of the transmitted light is emitted from the inside of the drum; the light source reflecting the draft is emitted from the outside of the drum. Light reflected or transmitted from a small spot on the image enters the receiver located outside the rotating drum. These rays are directed onto semi-transparent mirrors or beam splitters, which are at a 45 degree angle to the beam. Some light is reflected by the lens, and the rest of the light is transmitted to the other mirror. The reflected light passes through the red, green and blue filters and then enters the three PMTs, respectively. Through the PMT signal, once again through the analog-to-digital converter, from the analog signal into a digital signal. Each four PMTs may provide image sharpening information, although software sharpening after scanning will be more flexible.
PMT technology can record a large range of density changes, but its complexity also leads to manufacturing and maintenance costs, much higher than CCD devices. In most PMT scanners, operators are required to have excellent technical expertise and practical knowledge to optimally set up the scanning process. Only soft originals can be operated on such a device, and the installation of such originals is also time consuming. For hard manuscripts, you need to turn it into a soft manuscript. Valuable soft originals must be backed up before use to avoid damage during installation and rotation scans.
CCD sensor: The photosensitive device used in the platform scanner is a linear CCD array. In a row of a silicon chip, it generally includes several thousand photoelectric coupling units. The original to be scanned is placed on a glass plate. The light source of the manuscript is generally a fluorescent lamp and a halogen lamp. The light source for the transmission of the original is from above; and the light source of the reflection manuscript is from below. A light source with a mirror, through another mirror and a synchronously focused lens, can directly and continuously scan each line of the image onto a static CCD array during longitudinal movement.
The overall width of an image can be read simultaneously as a line. Light of a specific color and intensity is irradiated on each CCD element to generate a corresponding charge thereon. These analog charges systematically pass through this line array to an A/D converter, which in turn converts these signals into digital signals. In this way, the CCD is cleaned again to accept the next line of charge.
The grayscale scanner obtains a set of light intensity information from the original. The color scanner can obtain three sets of information from color originals through red, green and blue color filters. If there is only one CCD array in the scanner, it is sometimes necessary to rotate the RGB color filters in the lens to obtain three sets of information on the original. One-pass scanners may use three-row CCD arrays coated with red, green, and blue color filters, respectively. In this way, the same row of image data can be focused on each array at the same time.
Although the three-pass scanning method will be slower than the single-pass method, the color registration is a key issue, so that the three-pass scanning method has more advantages. CCD photosensors are less sensitive to blue light than green light but more sensitive to red light. Red, green, and blue light will appear in slightly different positions by focusing. Some three-pass scanners are optimized for scanning speed and focus for specifying the color to read.
Once certain special features are considered, well-designed and highly integrated CCD photosensors, the range of image density that can be read will be very similar to the PMT range. Each CCD element on an array is somewhat different in sensitivity from others, and there may be a small amount of information when no light falls on it. Some devices compensate for these anomalies by accurately calibrating each CCD element. When the amount of light shining on a CCD element is excessive, its charge may spread to the surrounding elements and generate abnormal information. The solid-state design of CCD photosensors makes them more compact and mechanically simpler than PMTs. This scanner is also cheaper, more stable, and requires less voltage than PMT.
Digital cameras are ideally suited for use in the press industry because digital images captured can be immediately transmitted via modem or satellite for newspaper publishing. A standard film camera with a camera back can obtain high-definition images and transmit the data via cable to a fast hard disk. The RGB primary colors can be scanned at the same time or in three scans, requiring the camera to be mounted on a stable tripod and not allowing the selected subject to move. Although the camera with a back plane is more suitable for acquiring 3-D object images, it can be used like a platform scanner.
Video Camera: Moving a continuous image or a separate still image can be captured by a computer-based frame capture system such as a CCD video camera or video tape. Multimedia playback software can edit and use these moving images, although too large data limits the quality, size, and recording time of the images. If a video clip only records an important event, the resampling process may be used to increase the resolution of each frame so that these frames can be output with reasonable quality effects.
Photosensitive technologies Photomultiplier tubes and optocouplers both convert different brightness changes into continuous changes or analog voltage changes. Using an analog-to-digital converter's sampling process, this continuous change can be converted to a specified number of stages. The purity of a tiny analog signal is easily affected by noise generated from electronic interference or incorrect signals. Therefore, good signal-to-noise ratio is a critical issue when designing photosensors and related circuits. Most light sources and analog electronics require a certain amount of time to reach a stable operating temperature and conditions. Therefore, it is recommended that you turn on the scanner and wait a few minutes before starting the scan.
Here are two technical features of PMT and CCD:
PMT sensor: The conventional roller scanner uses a xenon light source or a tungsten halogen light source. Both of these light sources can be focused on a small area of ​​the manuscript by means of an optical fiber and a condenser lens. The source of the transmitted light is emitted from the inside of the drum; the light source reflecting the draft is emitted from the outside of the drum. Light reflected or transmitted from a small spot on the image enters the receiver located outside the rotating drum. These rays are directed onto semi-transparent mirrors or beam splitters, which are at a 45 degree angle to the beam. Some light is reflected by the lens, and the rest of the light is transmitted to the other mirror. The reflected light passes through the red, green and blue filters and then enters the three PMTs, respectively. Through the PMT signal, once again through the analog-to-digital converter, from the analog signal into a digital signal. Each four PMTs may provide image sharpening information, although software sharpening after scanning will be more flexible.
PMT technology can record a large range of density changes, but its complexity also leads to manufacturing and maintenance costs, much higher than CCD devices. In most PMT scanners, operators are required to have excellent technical expertise and practical knowledge to optimally set up the scanning process. Only soft originals can be operated on such a device, and the installation of such originals is also time consuming. For hard manuscripts, you need to turn it into a soft manuscript. Valuable soft originals must be backed up before use to avoid damage during installation and rotation scans.
CCD sensor: The photosensitive device used in the platform scanner is a linear CCD array. In a row of a silicon chip, it generally includes several thousand photoelectric coupling units. The original to be scanned is placed on a glass plate. The light source of the manuscript is generally a fluorescent lamp and a halogen lamp. The light source for the transmission of the original is from above; and the light source of the reflection manuscript is from below. A light source with a mirror, through another mirror and a synchronously focused lens, can directly and continuously scan each line of the image onto a static CCD array during longitudinal movement.
The overall width of an image can be read simultaneously as a line. Light of a specific color and intensity is irradiated on each CCD element to generate a corresponding charge thereon. These analog charges systematically pass through this line array to an A/D converter, which in turn converts these signals into digital signals. In this way, the CCD is cleaned again to accept the next line of charge.
The grayscale scanner obtains a set of light intensity information from the original. The color scanner can obtain three sets of information from color originals through red, green and blue color filters. If there is only one CCD array in the scanner, it is sometimes necessary to rotate the RGB color filters in the lens to obtain three sets of information on the original. One-pass scanners may use three-row CCD arrays coated with red, green, and blue color filters, respectively. In this way, the same row of image data can be focused on each array at the same time.
Although the three-pass scanning method will be slower than the single-pass method, the color registration is a key issue, so that the three-pass scanning method has more advantages. CCD photosensors are less sensitive to blue light than green light but more sensitive to red light. Red, green, and blue light will appear in slightly different positions by focusing. Some three-pass scanners are optimized for scanning speed and focus for specifying the color to read.
Once certain special features are considered, well-designed and highly integrated CCD photosensors, the range of image density that can be read will be very similar to the PMT range. Each CCD element on an array is somewhat different in sensitivity from others, and there may be a small amount of information when no light falls on it. Some devices compensate for these anomalies by accurately calibrating each CCD element. When the amount of light shining on a CCD element is excessive, its charge may spread to the surrounding elements and generate abnormal information. The solid-state design of CCD photosensors makes them more compact and mechanically simpler than PMTs. This scanner is also cheaper, more stable, and requires less voltage than PMT.
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