dpi means resolution, which is one of the measurement units of resolution. It is used for dot matrix digital images. It means the number of sampled or displayable or output points per inch of length. DPI is a unit of measurement for the resolution of printers, mice and other devices. It is one of the main parameters to measure the printing accuracy of a printer. Generally speaking, the higher the DPI value, the higher the printing accuracy of the printer.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
dpi means resolution and is one of the units of measurement for resolution.
DPI (Dots Per Inch) is a unit of measurement for dot matrix digital images, which refers to the number of sampled, displayable or output dots per inch of length.
DPI is a unit of measurement for the resolution of devices such as printers and mice. It is one of the main parameters to measure the printing accuracy of the printer. Generally speaking, the higher the DPI value, the higher the printing accuracy of the printer.
DPI refers to pixels per inch, which is the scanning accuracy. The lower the DPI, the lower the resolution of the scan. Due to the influence of network transmission speed, the pictures used on the web are all 72dpi, but this parameter cannot be used for developing photos, it must be 300dpi or higher 350dpi. For example, if you want to develop a 4*6-inch photo, the scanning accuracy must be 300dpi, then the file size should be (4*300)*(6*300)=1200 pixels*1800 pixels.
#The higher the DPI value of the resolution set by the printer, the finer the printed image will be. Printers can usually adjust the resolution. For example, the resolution of a striker printer is usually 60 to 90 DPI. Inkjet printers can reach 300~720 DPI. Laser printers have 600~1200 DPI.
General monitors are 96 DPI, and the DPI number of bitmaps required for printing depends on the number of printing screen lines. Generally, 150-line printing quality requires a 350 DPI bitmap. And the D (dot) here is the pixel.
Because the printer’s color mixing method is CMYK, the color (that is, color gamut) performance is not as abundant and vivid as the screen’s RGB color light performance, so the printer’s DPI should be greater than the monitor’s PPI (Pixels Per Inch, pixels per inch), can achieve the same delicate picture quality as RGB on the screen.
The difference between ppi and dpi
ppi (pixels per inch): The sampling rate of the image (the number of pixels per inch in the image)
dpi (dots per inch): Printing resolution (the number of dots that can be printed per inch, that is, printing accuracy)
ppi and dpi are indeed two concepts, but some things are agreed upon. The ppi of a picture cannot reflect the print quality that this picture can get in a print shop. It is better to go to the store and try it. If you ask the operator what kind of print quality you will get if your picture is 72ppi, most operators will be confused. . Only dpi is used in printing shops, because the pictures we take must be output into photos. For the operator, what he needs to know is the pixels of your picture and the size you need to print. These two elements constitute dpi. , so although it is not standardized, we can only use the dpi size to communicate the pictures that need to be printed.
"Get it into Photoshop and change it to 300ppi. It has no practical meaning and increases the size of the image." Because such a change is a modification of ppi under a fixed image size (dimension), which results in the image being The number of pixels increases unrealistically, resulting in an expansion of the image size and no improvement in image quality (the extra pixels are calculated from the difference). The correct way is to first crop according to the proportion of the size you need to enlarge. your picture, then fix the pixels of the picture (uncheck the check mark in front of "Redefine the pixels of the picture") and proportion, adjust the width and height in "Document Size" to be consistent with the expansion size you want, and then come out The ppi is the dpi that your picture can get at this printing size. If it is lower than 120, it means the printed effect will be poor. 120~200 means the effect is okay. 300 is the best effect. If it is greater than 300, first print it. Check "Redefine the pixels of the image" and then change the ppi to 300 or lower.
(Note: 300dpi is the limit of the printing machine. Images larger than 300dpi will not improve the photo clarity. In fact, 250 is enough. Even if you input image files larger than 300dpi to the printing machine, the printing machine The image will also be calculated to 300dpi before enlarging it. In addition, don’t underestimate the 300dpi of the printing machine. The photo quality of the 300dpi of the printing machine is insurmountable by any printing equipment.)
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