= The difference between DPI and PPI =
Many people do not understand the relationship between DPI and PPI:
DPI (Dots Per Inch) refers to how many dots per inch.
PPI (Pixels Per Inch) refers to how many pixels per inch.
DPI is the name for picture output in printing, which is generally used for printing
PPI is the name of picture display generation, which is generally used for the parameters of picture display accuracy.
No matter what you call it, the pixels of the picture is essentially the same.
DPI is mostly used for printing
When printing, 300DPI is generally required.
If you use an outdoor inkjet printer to print, you can use 30~45DPI due to the long viewing distance.
In the indoor advertising category, a photo machine is used, and because the viewing distance is relatively close, 72~200DPI is used.
PPI is used for image display accuracy
Many people think that the display requirements of the screen will be lower than that of printing, but looking at the parameters of the mobile phone (iPhone 13), the PPI has reached 460.
That is to say: a picture of 460x460 pixels can only display 1 inch (25.4mm) on the screen of IPHONE13.
In printing, only 1.533 inches (38.9382mm) can be printed.
If you use an inkjet printer to print, when using 30~45DPI, you can print 15.33 inches (389.382mm)~10.22 inches (259.588mm).
If you use a photo machine, when using 72~200DPI, you can print 6.39 inches (162.306mm)~2.3 inches (58.42mm).
So, DPI and PPI can be used interchangeably in theory, do you understand?