What to do if you need to send a printed image on paper by e-mail? Probably, everyone already knows such a device as a scanner. It has repeatedly helped people save old photographs that our grandfathers and grandmothers took, translate some important documents into electronic format without having their source on a PC.
In general, a scanner is a useful thing and nowadays it is simply irreplaceable in many offices. In order to correctly determine which model you need, you should study the basic characteristics of the scanner.
What is it?
It’s better not to refer to scientific terms, but to explain in simple terms what kind of device it is. The scanner is responsible for performing the reading process, which is directed to a flat storage medium (eg, paper). Ultimately, the user receives a digital document for transmission over a distance or storage in electronic format. Scanning leads to the creation of a digital image of the external image of the object due to the ADC. Then the picture is sent to the computer using the input / output system.
First attempts
Few people know, but the basic characteristics of the scanner have been known to researchers since 1857. Then an abbot from Florence Giovanni Caselli created an alternative to the modern device. His device worked very primitively in relation to current technologies. Then, in order to transmit the image at a distance, it was necessary to apply it to the drum using conductive ink, and later read the image using a needle. Such a device was called pantelegraf.
Within half a century, a German physicist conducted his experiment, during which telefax was patented. Arthur Korn has developed a photoelectric scanning technique. Its principle was not easy: the picture was attached to the same drum, but already transparent. The lamp was so fixed that the stream of light could move. It passed through the original image and was sent to a selenium photodetector, and then penetrated through a prism and lens.
The faster semiconductors developed, the sooner the photodetector improved. Despite the fact that they later invented the tablet method, the principle itself remained virtually unchanged.
Characteristics
Before sorting out the views, you need to pay attention to the technical specifications of the scanner. There is a whole range of them, and there is no generally accepted classification. Each parameter depends on the purpose of the device. Nevertheless, there are basic characteristics by which you should choose a scanner. Among them, the speed of work, color depth, resolution of the received image, etc.
Beauty in detail
The characteristics of the scanner are varied, but resolution is one of the main parameters. In plain language: this property is responsible for the size of the smallest details of the picture that will be transmitted during scanning. Resolution is indicated in dpi. This value shows the number of visible dots per inch of image. Typically, the manufacturer indicates the performance of all three permissions:
- mechanical;
- optical;
- interpolation.
The first is to determine the location of the carriage with the CCD-ruler while moving in the image. The fact that the mechanical resolution is two times the optical resolution is used by the manufacturer against an incompetent user. In TX, he indicates that the optical value is 300x600 dpi. But if there is no interpolation on the device, then it will work with a minimum value of 300 dpi.
Interpolation resolution is responsible for the size that can be obtained by scaling the image 16 times. In principle, this is the least important parameter, and it practically does not carry any additional data. But its manufacturer can also use it against the buyer, indicating 4800 dpi on the box. Such a figure can impress an ignorant person. But everyone who does not know the characteristics of the scanner, but is going to buy this device for himself, must take into account that the actual optical value can be only 300 dpi.
The main parameter is the optical resolution. To determine it, you need to calculate the concentration of elements in the photosensitive ruler. To do this, you need to divide the number of parts on it by its width. This parameter, as mentioned earlier, is the most significant in determining the detail of the picture. Therefore, it is rarely seen on the box with the device, since both the manufacturer and the seller try to hide the real indicators.
Dry numbers
As mentioned earlier, it is not easy to choose such a device. The characteristics of scanners can confuse an inexperienced buyer, so it is better to delve into each parameter before purchasing. The next after resolution is bit depth, or hue depth. This characteristic indicates the number of bits that are needed to store color information for each pixel. Black and white scanners need the least memory. They have one rank. Monochrome is a little more - 8, and color - 24 digits. Scanners in the more expensive segment may be 36-bit.
The color depth is external and internal. These indicators are indicated by the manufacturer. The internal one is characterized by the capacity of an analog-to-digital transformer; it helps to determine the number of colors that a scanner can “see”. External depth is the number of shades that the device is capable of transmitting to a PC.
If you need a device in the office or home, the usual bit depth is suitable - 24 bits. If you need a scanner for printing and similar organizations, it is better to look for a 48-bit device.
Optical density
The scanner’s specifications do not end there. There is a maximum optical density. If you do not go into details and scientific explanations, this is the device’s ability to scan dark images: the more sensitive the device, the better the dark areas of the image are digitized.
Along with this parameter, there is an optical density range. It can be calculated with decimal logarithm. It is equal to the ratio of the amount of light incident on the original to the amount of light reflected. On average, the range for 24-bit capacity should be 1.8-2.3 D.
Speed
This parameter is also often forgotten to indicate, or completely tricked. However, the scan rate depends on several factors. Primarily, this is the resolution and size of the script. Speed can indicate the number of pages per minute, or simply the time at which one sheet goes through processing. There is also a measurement of scanned lines per second.
The size of the scanned area can also be varied. The most common solution is A4 sheet. Such models are found in offices and homes. At some enterprises they can use the A3 format. For handheld scanners, the strip size is 11 cm.
Interface
Not always scanner specifications are of particular importance. You can send a device parameter such as an interface to this category. It can be of several types. This includes its own interface from the developer. It was previously used in scanner models. Its popularity faded after the opportunity appeared to update the PC operating system. This was due to the fact that after the release of sales, this or that scanner was deprived of optimizing its interface for another system, which means that it did not function at all.
The following interface received a parallel port, which can now be found in younger samples of flatbed scanners. These devices are quite mediocre and do not stand out. They are usually used to scan photos or a couple of pages of text.
The PCMCIA interface can also be found infrequently, but SCSI remains the standard for devices with high quality and performance. Now with this interface produce more powerful machines with 30 and 36-bit.
The USB interface is the latest and most fashionable. It is actively recommended for many models, however, not good enough for high-performance devices.
Light source
This parameter is rarely taken into account when choosing a scanner. There are three types of lighting:
- xenon;
- fluorescent
- LED light.
Xenon lamps are small, they last a long time and are characterized by a short warm-up time. Fluorescent lighting is quite cheap, but it will also last a very long time. LEDs are small, consume little energy and heat up quickly. Usually it is the latest LED scanners that are considered to be of higher quality.
Diversity
After the scanner itself appeared directly, it began to be modified and take different forms. Now this device can be classified by a number of parameters. The types of scanners and their characteristics have now become generally accepted, and so far no technological innovations in this area have been observed.
To break these devices into categories, you need to study the following symptoms:
- imaging method;
- the structure of the kinematic mechanism;
- kind of image;
- characteristic of the original;
- Interfaces: hardware and software.
Kinds
So, for all of the above parameters, you can pick up a scanner. He can be:
- tablet;
- book;
- manual;
- leaf-pulling;
- planetary;
- drum;
- ultrasonic etc.
In general, there are a lot of types of scanner. We will talk about the main and most popular.
The tablet is currently the most popular and convenient. Typically, this type of model is very high quality and fast. Outwardly similar to a tablet, that's why they got such a name. To scan an image with such a device, you need to open the lid, lay the sheet face down on the glass, close the lid and press "start".
The hand scanner does not have an engine. Therefore, to process the image, you need to move it yourself. The main advantage of such models is their price. But there are too many drawbacks: poor resolution, poor scanning quality and low speed.
Book scanner is designed for processing brochure documents. In order to scan the necessary information, it must be laid down not “face”, as in a tablet, but up. The quality is very good.
The sheet-pull scanner is not very comfortable. To process the document, the sheet is inserted into the slot and pulled through the shafts inside. This scanner works with certain formats and single sheets.
The planetary apparatus works with papers that are easily damaged. It eliminates contact with the object, due to which you can maintain the integrity of the material.
Drum devices are found in printing companies and produce high-quality images. Slide scanners work with film slides. We meet barcode scanners every time we come to the cashier in the store. A 3D device is something newfangled. It can scan real objects that are converted to digital form and transformed into a three-dimensional model. An ultrasound scanner is a famous ultrasound scan used in medicine to examine internal organs.
Four in one
There is a multifunction device (MFP), which combines a copy module, facsimile mechanism, printer, scanner. Its characteristics are different. Basically, such devices can be inkjet, laser or LED by printing technology. Like any scanner, the MFP can be color or monochrome.
The main advantage of such a device is the saving of space at home or in the office. The user does not need to move paper from one place to another. It is convenient to work with one device. Also, MFPs have a fairly small price, relative to the amount that would have to be paid for a separate purchase of each device.
New in 2016
When you familiarize yourself with the characteristics of the scanner, you can begin to search for this device. This year there were many new models that may interest the user. For example, an HP ScanJet scanner, whose performance is impressive, can cost as little as 2 thousand rubles. At the same time, you will have access to a device with a 48-bit color scan depth, a popular USB 2.0 connector and compatibility with many operating systems. In general, HP scanners, whose performance has always been at the highest level, are market leaders in this segment. The company also has excellent models of multifunction devices.
This year, those who impressed not only with the features, but also with the price, appeared on the market. Epson Perfection V850 Pro scanner features are really very high. In addition to the fact that this tablet device has an adapter for film sliders and a USB 2.0 interface, its main characteristic was the resolution of 6400 × 9600 dpi. Along with these parameters, the price of the scanner ranges from 80 to 100 thousand rubles.
Among the new products there is also a budget option. The Canon CanoScan 9000F's scanner features are mediocre. Its resolution is 9600 × 9600 dpi. The price is 12 thousand rubles. Reviews of this model on the "four". The thing is that marketers start their “song” again, talking about unprecedented parameters. In fact, instead of 48 bits, we get only 12. That is, in each channel, instead of 16, there are only 12 bits. Nevertheless, there are those who are satisfied with the speed of work, high resolution and quality of materials of the device itself.
In general, to choose a good scanner, scientists do not need to be, especially for ordinary users. Large scans are not required for scanning documents and photocopies. Ultrahigh speed is not important either. Therefore, it is better to choose the scanner that you really need in its full functionality.