Barcode scanner resolution knowledge

Barcode scanner resolution knowledge

Resolution

All types of scanners are marked with its optical resolution and maximum resolution. The unit of resolution is dpi, dpi is the abbreviation of English Dot Per Inch, which means the number of pixels per inch.

Optical resolution

Refers to the actual amount of information that can be acquired by the scanner's optical system, which is the resolution of the scanner's photosensitive element. For example, a scanner with a maximum scanning range of 216 mm × 297 mm (suitable for A4 paper) can scan a maximum width of 8.5 inches (216 mm), and its photosensitive original contains 5100 units with an optical resolution of 5100 ÷ 8.5 inches = 600 dpi. . Common optical resolutions are 300 x 600 dpi, 600 x 1200 dpi, 1200 x 2400 dpi or higher.

Color resolution (important parameters of the data collector's display)

Also known as color depth, color mode, color bit or color scale, in short, it is an indicator that the scanner distinguishes color or grayscale. Its unit is bit. The exact meaning of the color bit is how many "bits" are used to represent a pixel that is scanned. 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) ie 0 and 1, which represent black and white respectively; 8bit can represent 256 gray levels (2 8=256), they represent different gray levels from black to white; 24bit can represent 16777216 colors (2 24=16777216), generally more than 24bit colors are true colors, of course, 30bit, 36bit, 42bit model. In theory, the more color bits, the more realistic the color.

Resolution and file size

The general scanning application can automatically calculate the file size when you preview the original draft, but knowing the file size calculation method will help you make the appropriate choices when managing the scanned file and determining the scanning resolution. The calculation formula for the black and white image file is: horizontal size × vertical size × (scanning resolution) 2 ÷ 8. The calculation formula of the color image file is: horizontal size × vertical size × (scanning resolution) 2 × color depth × 1/8. For example, by scanning a normal color photo (3.5×5 inches) with a 24-bit color RGB method and a scanning resolution of 300 dpi, the obtained image file length is 5×3.5×300 2×24×1/8=4725000 Byte or 4.7 MB. .