Spis treści:
- 1 Basic information about scanners in a nutshell
- 2 Large-format scanners - applications
- 3 What else is worth knowing about scanners?
- 4 Drum scanner - basic information
- 5 How does the drum scanner work?
- 6 Application of drum scanners
- 7 Key technical parameters of the scanners
- 8 Flatbed scanners - application and operation
Drum scanners belong to a group of devices used for digitizing images recorded on paper or other media (such as film). A characteristic feature of scanners of this type is a transparent drum.
Basic information about scanners in a nutshell
Key functionality scanners is the conversion of an image into an electrical signal, which is then converted into a file that can be run using a computer. The finished scan is modifiable in appropriate graphics programs. Modern scanners are designed to process color images. Only a narrow group of devices support only black and white images. Such devices are mainly used for scanning documents.
The scanners are distinguished by their versatility. They are used by both individual users and businesses in the printing industry. They are used in the preparation of materials for printing.
In stores and other service establishments, on the other hand, they are tasked with reading bar codes quickly and accurately. Another application is in the banking sector, where scanners are used to precisely analyze and verify customer signatures. In addition, they are commonly used in offices and public institutions for scanning various types of documents, images, graphics, tables, photos, etc.
Large-format scanners - applications
A separate group of devices designed for scanning are large-format scanners. As the name suggests, they are used in scanning large images. Maps are a good example. Such equipment is commonly used in design offices, where employees use, among other things. Of CAD software.
What else is worth knowing about scanners?
The most important component of any scanner is the optical scanning unit, which consists of photoelectric sensors, an illuminator and an optical system. This group of components is responsible for processing the scanned image into electrical signals.
The entire optical assembly can move relative to the image or the image relative to the assembly. The mode of operation depends on the specific scanner model. By mode of operation and application, scanning devices can be divided into handheld, flatbed, large-format and drum scanners.
Drum scanner - basic information
A drum scanner is a specific type of device designed for image scanning. It is distinguished by a unique design, the main element of which is a transparent drum. It places the documents to be scanned.
During operation, the drum rotates all the time. When scanning transparent documents, the mirror and illuminator move along the axis of the drum. In contrast, when performing a scan of reflective images, the illuminator works on the outside of the transparent drum.
How does the drum scanner work?
The way the drum scanner works is through spiral movements against the surface of the drum. The light produced can reflect off the document or pass through it. In both cases, it is passed through mirrors, then through RGB filters and goes to photomultipliers. An electrical signal is generated in these elements, which is amplified in subsequent stages.
In the next step, the converter converts the electrical signal into a digital one, which is changed into a file in the appropriate format. In this form, it can be transferred to a computer or external memory, for example. Depending on the type of drum scanner, such devices are equipped with photomultipliers or special CCD arrays.
Application of drum scanners
The drum scanner is mainly used by professionals. It is used in the printing industry and in outlets offering high quality printing. Thanks to advanced software, the user can freely edit scanned images and make various corrections.
The drum scanner is more difficult to use than standard flatbed models. To maximize its potential, experience is essential. The key advantage of this type of device is very high quality and resolution, which often exceeds 10000 ppi.
Key technical parameters of the scanners
One of the most important technical parameters of scanners is scanning resolution. This is the value that determines the number of points that will be analyzed in a certain unit of area. Manufacturers use the unit ppi (pixels per inch). This is the number of pixels per inch of length. We distinguish between two resolutions. The first is optical resolution, which describes the physical capabilities of the device. The other is interpolated, referring to the points added to the image through the program.
Another parameter is the format of the scanner, which is the maximum physical size of the document that can be scanned with the use of a specific model of the device. The most popular formats are A4 and A3.
When reading the technical specifications of the scanner, it is also worth noting the interface, that is, how the device communicates with the computer. The most common communication interfaces are USB and LPT, although selected models also use SCSI.
Flatbed scanners - application and operation
Flatbed scanners are among the most popular scanning devices on the market. This is due to, among other things. from its simple operation, versatile application and good value for money. The scanned document is placed on a transparent plate, under which is an illuminator. During scanning, the document remains stationary, while the illuminator moves relative to it. This is how basic flatbed scanner models work. In the case of advanced equipment, the document is moved via transport carts, while the illuminator is stationary.
The flatbed scanner is distinguished by its high precision performance. In addition, it allows a wide range of modifications to the scanned image. The user can correct not only the sharpness, but also the contrast and even the colors. Other modifications include rotating, scaling and adding other images.
