Purchasing Method Of Scanning Gun

First we need to know what resolution is. All kinds of scanning guns are marked with their 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 see how important the following parameters of the scanning gun are to us.

Optical resolution refers to the actual amount of information that can be collected by the optical system of the scanning gun, that is, the resolution of the photosensitive element of the scanning gun. For example, the maximum scanning range is 216mm × The maximum scanning width of the 297mm (suitable for A4 paper) scanning gun is 8.5 inches (216mm). Its photosensitive original contains 5100 units, and its optical resolution is 5100 points ÷ 8.5 inches = 600dpi. The common optical resolution is 300 × 600dpi、600 × 1200dpi、1200 × 2400dpi or higher.

Color resolution is also called color depth, color mode, color bit or color scale. In a word, it is an indicator indicating the fineness of color or gray level distinguished by the scanning gun. Its unit is bit. The exact meaning of color bits is how many "bits" are used to represent a pixel obtained by scanning. For example, 1bit can only represent black and white pixels, because the numbers in the computer use binary, 1bit can only represent two values (2 1 = 2), i.e. 0 and 1, which represent black and white respectively; 8bit can represent 256 gray levels (28 = 256), which represent 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 30bit, 36bit and 42bit models. Theoretically, the more the number of color bits, the more realistic the color is.

Let's talk about the relationship between resolution and file size. General scanning application software can automatically calculate the file size when you preview the original sample, but understanding the calculation method of file size is more helpful for you to make appropriate choices when managing scanned files and determining scanning resolution. The calculation formula of black and white image file is: horizontal size × Vertical dimension × (scanning resolution) 2 ÷ 8. The calculation formula of color image file is: horizontal size × Vertical dimension × (scanning resolution) 2 × Color depth × 1/8。 For example, a normal color photograph (3.5 × 5 inches), and the scanning resolution is 300dpi, then the length of the obtained image file is 5 × three point five × 300 2 × twenty-four × 1 / 8 = 4725000byte, i.e. 4.7mb.

The last concept to be elaborated 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 the optical input equipment such as the scanning gun, and analyze the morphological characteristics of the characters by using the pattern recognition algorithm to distinguish different Chinese characters. Chinese OCR is generally only suitable for recognizing printed Chinese characters. The use of scanning gun and OCR can partly replace the function of keyboard to input Chinese characters, which is a labor-saving and fast character input method. Common OCR include Qinghua Wentong, Shangshu, Mengtian, etc. Add the specific application of scanning gun OCR recognition. The representative product is Honeywell 1900. The difference between it and flat-panel scanner is that it can recognize print fonts (unfortunately, it only supports English and Arabic numerals, but not Chinese). The common print font is ocr-a; OCR-B； Ocr-c three fonts. Personally, I prefer OCR-B, which is more similar to ordinary English printing fonts. The digital serial number on the bank check is an example in real life. 1900 can directly read the serial number through setting. Some packages in the foreign logistics industry print the receipt label on the spot. Human eye recognition and scanning gun recognition can share the same character string, which greatly improves the operability; Convenience and quickness.