Comparison Kodak i940 vs Canon P-215

Small size scanners designed for maximum portability. Usually they are cylindrical or rectangular devices with a through slot through which the scanned document is passed during operation; thus, the size of such a scanner is much smaller than that of a traditional scanner, in which the entire document must be placed. Portable scanners tend to be of low resolution and are intended primarily for light tasks such as scanning text documents. They are well suited for use with laptops — in particular, the dimensions allow them to be transported in the same bag with a laptop computer.

The maximum image size that the scanner can process at one time, both horizontally and vertically. You should pay attention to this parameter if you need the exact dimensions of the scanner's working area, down to a millimetre: although standard formats are used to designate these dimensions (see "Format"), in fact the dimensions may differ from them.

External colour depth characterizes the maximum possible number of colour shades in the image transmitted by the scanner to the computer. A depth of 24 bits is considered quite enough for non-professional tasks, in more advanced models this parameter can reach 96 bits. For details on colour depths and their relationship, see "Colour Depth (Int.)"

The number of shades of grey that the scanner recognizes. You should pay attention to this parameter if you plan to actively work with complex black-and-white materials (for example, photographs) — the more shades, the higher the quality of the digitized image. To date, the average is considered to be 512 shades — this approximately corresponds to the capabilities of the human eye. Models with a lower indicator belong to the entry level, more advanced ones “understand” 1024 shades.

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.

Availability of duplex scanning function in the device. Duplex scanning in this case means such an operating mode in which the scanner simultaneously captures an image from both sides of the processed medium (sheet of paper). The convenience of this feature is obvious: the media does not have to be turned over to scan each side separately, and the processing time is significantly reduced. Double-sided scanning is found mainly in the models of traction or combined type (see above), however, there are also flatbed scanners with this capability.

By default, the scanner is designed to work with reflective, i.e. opaque materials (such as paper). The slide module allows you to use the device for processing transparent materials, such as photographic film.

— 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).