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How to choose a barcode scanner

First of all, we need to know what the resolution is. All kinds of scanners are marked with optical resolution and maximum resolution. The unit of resolution is DPI. DPI is the abbreviation of dot per inch, which means the number of pixels per inch. After understanding the meaning of resolution, let's take a look at how important the following parameters of the scanner are to us.barcode scanner.jpg
Optical resolution refers to the amount of information that the optical system of the scanner can actually collect, that is, the resolution of the photosensitive element of the scanner. For example, the maximum scanning range is 216mm×297mm (suitable for A4 paper) and the maximum scanning width of the scanner is 8.5 inches (216mm). Its photosensitive original contains 5100 units, and its optical resolution is 5100 dots÷8.5 inches=600 dpi. Common optical resolutions are 300×600dpi, 600×1200dpi, 1200×2400dpi or higher.
Color resolution is also known as color depth, color mode, color bit, or level. In short, it is an indicator of the fineness of the color or grayscale that the scanner distinguishes. Its unit is a bit. The exact meaning of color bits is how many "bits" are used to represent a scanned pixel. For example, 1bit can only represent black and white pixels, because the numbers in the computer are binary, and 1bit can only represent two values (2 1 = 2), namely 0 and 1, representing black and white respectively; 8bit can represent 256 1 gray level (28=256), representing different gray levels from black to white; 24bit can represent 16777216 colors (224=16777216). Generally, colors above 24bit are called true colors. Of course, there are also three models 30bit, 36bit, and 42bit. In theory, the more color bits, the more realistic the color.
Let's talk about the relationship between resolution and file size. General scanning application software will automatically calculate the file size when previewing the original, but understanding the calculation method of file size will help you make an appropriate choice when managing scanned files and determining the scanning resolution. The calculation formula for black and white image files is horizontal size × vertical size × (scanning resolution) 2÷8. The calculation formula for color image files is horizontal size × vertical size × (scanning resolution) 2 × color depth × 1/8. For example, for an ordinary color photo (3.5×5 inches), the scanning resolution is 300dpi, and the length of the obtained image file is 5×3.5×300×2×24×1/8 = 4725000byte, which is 4.7 MB.
The last concept to be explained is OCR. It is the abbreviation of English optical character recognition. Its function is to read the character image information on the printed matter through optical input devices such as barcode scanners and use pattern recognition algorithms to analyze the morphological characteristics of characters and distinguish different Chinese characters. Chinese OCR is generally only suitable for recognizing printed Chinese characters. The use of scanners and OCR can partially replace the function of keyboard input of Chinese characters, which is a labor-saving and fast way of Chinese character input. Common OCRs include Tsinghua Wentong, Shangshu, Mengtian, etc. Add the specific application of scanner OCR recognition. The representative product is Honeywell 1900. The difference between it and the flatbed scanner is that it can recognize printing fonts (unfortunately, it only supports English and Arabic numerals, not Chinese). Common printing fonts are OCR-A; OCR-B; Ocr-c three fonts. I personally prefer OCR-B, which is closer to ordinary English printing fonts. A real-life example is the digital serial number on a bank check. 1900 can read the serial number directly through the setting. Some packages in the foreign logistics industry print receipt labels on the spot. Human eye recognition and scanner recognition can share the same string, greatly improving operability; convenience, and quick.


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