Scanner - is a device that analyzes an object (usually an image, text), creates a digital copy of the image of the object. The process of obtaining this copy is called scanning.
Optical Resolution
Considered to be the main feature of the scanner. The scanner takes an image is not complete and the rows. Vertical flatbed scanner moves the band of light-sensitive cells and removes the points image line by line. The more light-sensitive elements in the scanner, the more points it can be removed from each horizontal band image. This is referred to as the optical resolution. It is determined by number of photosensitive elements (photocells) per inch horizontally scanned image. Traditionally it is considered by the number of dots per inch - dpi (dots per inch). The normal level of resolution at least 600 dpi, to increase it even further - then use expensive optics, expensive light-sensitive components, and to increase the scan. To process the slide to the most highest resolution of 1200 dpi.
Resolution X
This parameter specifies the number of pixels in a photosensitive line, from which an image is formed. Resolution is one of the main characteristics of the scanner. Most of the models has an optical resolution of the scanner 600 or 1200 dpi (dots per inch). It is sufficient to obtain high quality copies. For professional image to a higher resolution.
Y resolution
This option orients the travel of stepping motor and precision mechanics. Mechanical scanner resolution is much higher optical resolution fotolineyki. That line of optical resolution photocells will determine the overall quality of the scanned image.
Scan speed
The scanning speed depends on the resolution of the scan and the size of the original. Traditionally, manufacturers have this option for the A4 format. Scan speed can be measured by number of pages per minute, or the time required to scan a single page. Sometimes measured in the number of scan lines per second.
Color Depth
Typically, manufacturers specify 2 values for the color depth - the depth of the inner and outer. Internal depth - this is the bit ADC (analog-to-digital converter) of the scanner, it shows the degree to color scanner is able to recognize in principle. External Depth - is the number of colors that can transmit a computer scanner. Most of the models are used for 24-bit color (8 for each color). For common tasks in the office and at home it is completely sufficient. However, if you intend to use the scanner, for serious graphics work, try to find a model with a lot of places.
Maximum optical density
Maximum optical density of the scanner - is the optical density of the original, which vary from scanner 'total darkness'. The more the number, the more sensitive the scanner, the higher the scan properties of dark images.
Type of light source
Xenon differ little warm-up time, long life and small dimensions. Fluorescent lamps, cold cathode, cheap to produce and have a long service life. LEDs (LED) have small size, low power consumption and does not require time to warm up. However, the quality of color LED-scanners scanners yield of fluorescent and HID lamps.
Kind of sensor scanner
Scanners MFP typically used one of 2-sensor types: contact (CIS) or CCD (CCD). CIS is a line of solar cells, which is the same width of the scan plane. During the scan, it moves under the glass and line by line transmits the image to the original in the form of an electrical signal. Traditionally used for lighting LEDs, which are placed in a specific proximity fotolineyki on the same moving platform. CIS scanners are based on unit design, slim and light weight, they are usually cheaper scanners based on CCD. The main drawback is the CIS little depth of field.
Types of scanners
Tablet - better known discharge scanners, since it ensures the best user experience - high quality and affordable scanning speed. Is a tablet, inside which is placed under the clear glass scanning engine.
hand - there is no engine, consequently, the object has to scan the user manual, one of his advantage is low cost and portability, with this he has a lot of shortcomings - low resolution, a little speed, narrow strip scan, likely skewed because the user will be difficult move the scanner at a constant speed.
listoprotyazhnye - paper is inserted into the slot and pulled on the guide rollers inside the scanner by the lamp. Smaller in size, compared with the tablet, but it can only scan single sheets, which limits its application in the main office. Almost all models have automatic feeding device that allows you to quickly scan a large number of documents.
planetary scanners - used to scan books or easily damaged documents. When scanning is no contact with the scanned object (as in flatbed scanners).
book scanners - are designed for scanning documents stitch. Scans face up - so your actions on scanning indistinguishable from turning pages at ordinary reading. This prevents them from defect and allows the user to see the document during scanning.
slide scanners - as is clear from the name, are used to scan film slides are available as stand-alone device or in the form of additional units to the usual skaneram.
Function
The scanned object is placed on the glass surface of the scanned surface downwards. Under the glass is placed a movable light, movement is regulated by a stepper motor. The light reflected from the object, through the mirror falls on the sensitive matrix on the ADC and sent to the PC. For each step of the motor strip scanned object, which later joined the software into a continuous image.
Continuously scanned image format RAW - and then converted into ordinary graphical format using the current settings for brightness, contrast, etc. This conversion is performed either on the scanner, or in a computer - depending on the specific scanner model. On the characteristics and properties of RAW-data affected by such hardware options scanner as the exposure matrix, calibration levels of black and white, etc.