Source: WeChat public account PingMianDesigner (graphic design)
Resolution, also known as resolution, resolution, can be subdivided into display resolution, image resolution, print resolution, and scan resolution. Resolution determines how fine the bitmap image details. In general, the higher the resolution of the image, the more pixels it contains, the sharper the image, and the better the quality of the printing.
Resolution is described in units of dpi (dots per inch), lpi (line per inch), ppi (pixels per inch), and PPD (PPPixels Per Degree angular resolution, pixels per degree).
There are five common device resolutions: scanner resolution (ppi), digital camera resolution (ppi), computer screen resolution (ppi), printer resolution (dpi), and press resolution (lpi). Each has its own uses and characteristics, but it can be divided into two categories according to whether it is input or output.
Common image acquisition devices are scanners, digital camera DC, digital camera DV, they sample and quantify the natural continuous distribution of scenery information for computer processing and preservation, the imaging devices in these devices combine photoelectric conversion and sampling functions.
Whether ccD devices or CMOS (more power-saving, higher unit integration devices), each CCD (or CMOS) imaging unit completes a pixel data acquisition, then the imaging accuracy of the device is subject to the CCD or CMOS integration accuracy, that is, subject to the accuracy of the manufacturing process, the current resolution of these devices to improve, almost as fast as the computer world's Moore's Law, has approached the traditional chemical method of silver salt emulsion film accuracy (that is, film).
(1) Scanner resolution. The scanning process of a scanner is to divide a photo or picture into millions of mosaic-like "pixel squares". When scanning, the scanning resolution DPI (dots per inch) can be set on the basis of the resolution of the device with its existing physical properties, which means that during the scanning process, the scanner arranges how many "pixels" are arranged in each inch range on the long and short sides of the scanning window.
If the resolution of a scanner on a certain A4 format is known to be di =2000 on the long side and ppi=1300 on the short side, the image will be divided into (297/25.42000) × (210/25.4×1300) = 239.6MB pixel squares by the scanner. It is important to note that the scan resolution setting should not exceed the inherent physical resolution of the device, otherwise it does not make sense.
(2) Digital camera resolution. Very similar to the resolution of a scanner, if you take a digital camera resolution = 200 pixels side length / inch, the total "pixel square" of a 6-inch × 4.5-inch photo should be (6×200) × (4.5×200) = 1,080,000 "pixel squares" (commonly known as 1 megapixel).
(1) Computer screen resolution. When the computer receives the image file, the computer has rearranged the pixels according to its own screen size. For example, a screen resolution of 1366x768 screens divides 1366 and 768 pixels, so that the entire screen forms 1366×768 pixel squares.
The photo or picture files sent from the scanner or digital camera, following the pixel squares they have divided, are placed on the pixel squares of the computer screen in an orderly row, thus forming an image on the computer screen.
(2) Printer resolution. After an image file is delivered to the printer, the printer always redivides the image file at its own resolution (300, 600, or greater color dots per inch), and then sprays various colors of pigments (ink or toner) onto the corresponding color points.
The larger the resolution, that is, the more color points there are, the more delicate the color of the printed image. Different printers have their own rules for dividing pixel squares, so the size of the photos printed by different printers is different.
(3) Printing machine resolution. The meaning of the printing machine resolution (line per inch, screen cable / inch) is: before the image is printed, the printing machine always has to RIP (Rasterized Image Processing), and the special software module is responsible for converting the pixel values into the corresponding dots, according to the artistic requirements of the print, the image file is arranged "screen line".
Then a variety of colors of ink, sprayed in the screen crisscrossed to form a grid to form a dot, the size of the dots is uneven to reflect the shade of color, which in the printing field is also called semi-tonal processing, is a technical core in the field of digital printing. The higher the Lpi value, the larger the color block, the more and finer the color block, the more the printed image color can achieve higher clarity and brilliance.
With the advent of the information technology and digital age, we are surrounded by a variety of digital terminal reading devices (computer monitors, mobile phones, pads). On the basis of the continuous invention and emergence of information output devices, resolution is an eternal topic, such as mouse resolution, touch screen resolution, projector resolution, all have a new definition and understanding.
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