Comparison IRIS Reader 8 vs IRIS Express 4

— A0. The largest sheet size specified by the ISO 216 standard is 1189x841 mm (4 times the size of a newspaper spread). It is found exclusively in broaching-type devices (see above), belonging to the professional class.

— A1. Sheet size 594x841 mm. For a number of reasons, this option has not received much distribution in scanners.

— A3. Sheet size 297x420 mm, i.e. 2 times larger than the standard landscape. Support for this format allows you to scan quite large materials, such as an entire spread of a magazine or a page of a newspaper, in one pass.

— A4. Standard landscape sheet 210x297 mm, the most common paper format today, especially in office documentation. Most scanners have this format, it is enough for most personal and work tasks.

— A5. 148x210 mm, in other words — half of a standard landscape sheet. Scanners for this format are compact, but they are very rare, because. working with the popular A4 format on them is at least inconvenient.

— A6. 105x148 mm, a quarter of a standard landscape sheet. Such scanners are small in size and are convenient for working with photographs, where the standard print size (10x15 cm) is approximately equal to A6, but today they are almost never used for the same reasons as A5 (see...above).

Specifies the maximum size allowed for scanning. Note that the actual size of the maximum scan area (see below) may be larger than the paper size specified in the specifications. And in broaching models (see "Type") the size of the processed materials is generally limited only by the width of the scanner. In fact, manufacturers indicate the maximum size in order to make it easier for the user to determine the capabilities of the scanner and its compatibility with popular paper sizes.

The highest resolution of the digital image generated by the scanner during operation. Specified in dots per inch — dpi (dots per inch).

The higher the scan resolution, the higher the resolution of the resulting image will be (with the same size of the source material) and the more accurately small details will be transmitted on it. On the other hand, high resolution noticeably affects the price of the scanner, increases the processing time and the size of the resulting file — despite the fact that the real need for high detail is not always present, and in some cases it is even unnecessary (for example, when processing an image with small artifacts, not visible at low detail). Therefore, when choosing by this parameter, you should not chase high resolution values — you should proceed from the real need and the specifics of the intended use of the scanner.

The simplest modern scanners have a resolution of about 300x300 dpi — this is quite enough for text recognition with an average font size. And in high-end professional models, this figure can exceed 7000x7000 dpi.

— CIS, abbreviation for "Contact Image Sensor" — contact image sensor. The simplest type of optical element: it is a line across the entire width of the scanner's working space, on which photocells that read the image and LEDs that provide illumination are located in a row. They are inexpensive and take up little space, which, accordingly, makes the scanners themselves cheaper and smaller. On the other hand, CIS sensors have a shallow depth of field, and even small bumps in the scanned image can be out of focus. However, in general, they are quite suitable for both personal and not too complex professional tasks.

— CCD, short for "Charge-Coupled Device" — a charge-coupled device. A much more complex design than CIS, includes a fluorescent lamp, lens and mirror. CCD scanners are larger, heavier and much more expensive than their counterparts in CIS. On the other hand, this type of optical element provides high-quality colour reproduction and a good depth of field, coping well with complex-shaped media. Therefore, advanced professional scanners are usually equipped with a CCD.

— CMOS. The abbreviation for "Complementary Metal-Oxide-Semiconductor" is a complementary metal-oxide-semiconductor structure (the designation CMOS is also used in Russian). A key feature of CMOS sensors is that they capture the scanned image as a whole, similar to photography (and not...line by line, as in other types of optical elements). In fairness, it should be noted that the "instantaneous" scanning does not give a tangible advantage in speed, because. processing the captured image takes quite a long time. However, this feature is extremely useful in cases where it is difficult to ensure the immobility of the scanned material and/or uniform movement of the optical element relative to this material. Such situations often arise when working with book and handheld scanners (see "Type"), so CMOS elements are most popular in such devices.

The black and white scanning speed provided by the device. Usually, the maximum processing speed for an A4 sheet is indicated, i.e. speed at the lowest resolution. In fact, the speed is usually lower and depends on both the resolution and the size of the original material. The higher the scanning speed, the more convenient it is to work with the scanner; pay special attention to this parameter if you plan to work with numerous black and white images.

Colour scanning speed provided by the device. In fact, it depends on the selected resolution, colour depth and original dimensions; the characteristics most often indicate the speed for an A4 sheet at the minimum resolution and colour depth, i.e. maximum possible speed. If you only need to scan one or more sheets from time to time, high speed is not too critical, but for working with a large amount of materials, you should look for fast models.

— Wi-Fi. A wireless interface primarily used to build local computer networks. In many respects it is similar to the LAN described below (in particular, it allows using the scanner as a network device), but it compares favorably due to the absence of a cable and the ability to work directly through walls. In addition, relatively recently, Wi-Fi modules have appeared with the ability to directly connect between devices — for example, to control a scanner from a tablet and transfer processed materials to the tablet directly, without creating a computer network. However scanners with Wi-Fi are quite expensive.

— USB. Universal interface for connecting various peripherals to a computer, including scanners. Today, it is the most common port of this type; at least one USB input is provided by the vast majority of PCs and laptops.

— SCSI. Universal interface for connecting computer peripherals; has a good speed, however, it is much less common than its analogues, besides it is considered obsolete and is gradually being replaced by other standards.

— IEEE-1394. Universal port, in many ways similar to USB (see above). Provides higher speed than the most common USB 2.0, but is much less common.

-LAN. Connector for connecting various devices to a local computer network. A scanne...r with this interface can be connected as a network device and used with it by any computer on the network, which can be especially useful in offices.

The presence of a slot in the scanner for a memory card, to save the scanned material directly to the media.

— From the network. The most common option is to connect to a conventional 230 V power supply. This power supply provides enough power to operate any, even the fastest and most performant scanners. Its disadvantage is, in fact, the need for an electrical network.

— From USB. Powered via USB port — the same through which it connects to the computer. This significantly increases the battery life of the scanner — in particular, it can be used with a laptop in places where there is no access to a 230 V network, which is especially important for portable models (see "Portable Design"). On the other hand, the performance of such devices is usually low, and the power of the USB port is not always enough for power supply (which is especially true when using USB hubs).

— Autonomous. Power supply of the scanner from its own batteries (accumulator or replaceable batteries). Such models are as autonomous as possible, because do not require a power cord to operate, and many of them are able to act as separate devices without being connected to a PC at all. Their disadvantage is the risk of switching off at the most inopportune moment due to the exhaustion of the charge — then you have to either change the batteries (which at least requires fresh ones) or recharge the battery (which takes time).