Basic parameters of flatbed scanners

Among the various models of scanners presented in stores, we can highlight tablet devices. This is a popular budget option that has all the necessary functions for digitizing documentation. We will talk about the main parameters of such scanners in our article.

Main characteristics of flatbed scanners

The device got its name thanks to a glass plate - a tablet on which the original photo (or document) is placed with the scanned surface facing down.

The main advantages of its use are compactness, ease of use and versatility. Documents are processed without additional influences (bending, deformation, etc.). The devices do not require maintenance and are designed for a long service life.

Power can be supplied from a battery, via a USB connector on a PC, or via Wi-Fi.

The device performs two main functions:

1. Digitization of text documents;
2. Scanning photos and various images.

REFERENCE! Processing of both color and black and white originals is provided.

The operation scheme is simple: inside the device there is a scanning head, which, when a command is given (manually or automatically), moves along with the light source using a stepper motor. Light rays are reflected from the document being processed, captured by a system of mirrors, then pass through light-sensitive sensors and converted into electrical signals. As a result, a digital copy of the image is formed from the signals.

Permission

This is the main characteristic of the scanner, on which the quality and detail of the resulting images depend.

The passport indicates two values, which mean horizontal and vertical resolution, respectively. The horizontal value is taken as the basis, since when processing the image the mechanism moves from top to bottom. It's called optical resolution.

In accordance with this indicator, tablet models are divided into classes:

1. Standard. Suitable for business document flow and general user needs, the parameter varies from 300 to 600 dpi.
2. Average. Used in publishing, resolution can reach 1800 dpi.
3. High quality, up to 2000 dpi and higher. Its parameters are not inferior to professional devices.

IMPORTANT! For scanning documents, the standard value is sufficient, but if the digitized photo will be processed in the future by graphic editors, then we recommend choosing the middle class.

Performance

This value indicates the speed at which documents are scanned. It depends on the selected resolution and document size - the higher they are, the lower the parameter in question.

For example, in one pass of the scanning head, a low-quality image (less than 300 dpi) is processed, which ensures high performance at the expense of other indicators.

Standard values ​​for budget devices are from 4 to 5 pages per minute, which corresponds to approximately 600 dpi.

Bit depth or color depth

Color rendering is calculated in bits and affects the colorization and number of shades of the document. The parameter is determined by the capabilities of photosensitive sensors (CCD or CIS) and the ADC (processor that converts the analog signal into a digital one).

Models are available with depth from 24 to 48 bits. You can find 96-bit models, but they are already of the professional type and are much more expensive.

Color depth, which measures how many colors a scanner can distinguish from an original, is called intrinsic color depth. Its optimal value for high-quality scanning is 36 bits.

The color representation that is transferred from the device to the computer is external. To obtain the best result comparable to the source, at least 36 bits are selected.

REFERENCE! These sensors differ in the type of light sources used: fluorescent (CCD) or LED (CIS), the latter last much longer.

Dynamic range

This parameter characterizes the difference between the lightest and darkest areas of the image. Simply put, it measures the scanner's ability to recognize how dark a source is. The so-called optical density increases as the darker shades increase.

For example, density 0.01 means white shades, up to 4 and higher means blackness indistinguishable to the eye.

White light is perfectly recognized by scanners, while at the same time, only sensors with high sensitivity are able to “see” dark areas.

The higher the dynamic range value, the better the final scanning result.

REFERENCE! In cheap models this parameter is usually not indicated. But you can roughly determine the numbers: 24-bit scanners perceive from 2.4 to 2.6; 30 bits – from 2.6 to 3; 36 bits – from 3.

PC connection type

Modern devices use a USB connection to a computer. The USB connection can be version 1.1 or 2.0. Structurally, these are the same type of connectors, differing in data transfer speed: 12 Mbit/s, compared to 480 Mbit/s. They are completely compatible and interchangeable.

Another connection option is parallel ports (SCSI or PCMCIA standards), they are connected to the rear panel of the PC, where there are corresponding connectors.

Scanned Document Format

Typically, the scanner driver supports recording received files in such common formats as Jpeg, PDF, etc.

In some cases, to save scanned texts, you may need to install a recognition program on your PC, if by default it is assigned one of the extensions designed for photos (Jpeg, tiff, etc.).

You can change the file format, for example, in the ABBYY FineReader application; it has an extensive set of tools for recognizing text blocks, adjusting and changing them, and then saving the result in the required file type. A wide range of extensions are available.

REFERENCE! The standard size of originals used is A4, but some models support A3, A5, etc.

Supported Operating Systems

As a rule, the device comes with a disk with a licensed program (driver), which ensures optimal operation. If there is no such floppy disk, then you need to go to the scanner manufacturer’s website and download the necessary utility.

According to user reviews, some models come with difficult-to-learn software; in these cases, an alternative may be to download and install the program from the Internet.

Manufacturers produce devices compatible with all popular Windows and MAC systems. There are no special requirements for the characteristics of these operating systems.

IMPORTANT! In some cases, incompatibility occurs, for example, Windows Vista may “conflict” with a new driver. The issue can be resolved by searching for a suitable program; as a last resort, you will have to install another OS.

Additional features of flatbed scanners

Auxiliary functions are implemented using elements such as film modules and automatic feeding of originals.

Some devices have a special adapter that allows you to scan photographic films, both negative and positive, and slides.

Using this tool, the so-called film scanner is replaced - a special device for digitizing films. The cost of specialized models can significantly hit the pocket, so having an additional function in a flatbed scanner can save the owner money.

Automatic feeding of originals allows you to load a stack of documents into the tray at once, which will move as they are scanned. This allows you to reduce the number of user actions, which is especially important when there is a large amount of work.

What parameters to consider when choosing a scanner for your home

Before purchasing, decide on the purpose of why you are purchasing the device, how often you will use it, and what level of quality will satisfy you.

When choosing a device, additionally evaluate the following indicators:

• convenient connection to a PC;
• equipment compatibility;
• options;
• available document sizes (A4 and others).

High requirements for the quality of the output material, the need to process originals of different sizes and the availability of auxiliary tools will make your purchase much more expensive.

Otherwise, a standard tablet at an affordable price is the best option.

We hope that our article helped you figure out what characteristics to pay special attention to when choosing a flatbed scanner.