What does screen ppi mean?

Screen ppi means the number of pixels per inch and is a unit of pixel density; ppi is the abbreviation of "Pixels Per Inch". The higher the value, the higher the density the display can display images. The higher the density of the display, the higher the fidelity and the richer the details of the picture.

The operating environment of this tutorial: Windows 10 system, DELL G3 computer.

What does screen ppi mean?

Pixels Per Inch is also called the pixel density unit, which represents the number of pixels per inch. Therefore, the higher the PPI value, the higher the density the display can display images. Of course, the higher the density of the display, the higher the degree of realism

Pixels Per Inch is the density unit of pixels, just like the higher the PPI value, the richer the details of the picture, so the digital camera will The pictures may differ due to different brands or production times. Common ones are 72PPI, 180PPI and 300PPI. This is the default number (A710 shoots 180PPI). DPI (Dots Per Inch) refers to the output resolution. For output devices, the output resolution of general laser printers is 300PPI-600PPI, printing imagesetters reach 1200PPI-2400PPI, and common printing is generally between 150PPI and 300PPI. between.

Concept

ppi (pixels per inch): The sampling rate of the image (in the image, the number of pixels per inch)

dpi (dots per inch): Printing resolution (the number of dots that can be printed per inch, that is, printing accuracy)

The relationship between printing size, the number of pixels of the image and the printing resolution can be Use the following calculation formula to express it:

The number of horizontal (vertical) pixels of the image = Printing horizontal (vertical) resolution × Printing horizontal (vertical) size,

The number of horizontal (vertical) pixels of the image Number of horizontal (vertical) pixels/printing horizontal (vertical) resolution = horizontal (vertical) size of printing.

For a specific image, the number of pixels of the image is fixed, so the printing resolution and printing size have an inverse relationship.

For example: if you want the size of the printed photo to be 4*3inch, and the printing resolution is 300dpi both horizontally and vertically, then the number of pixels collected by the camera needs to be at least (300*4)*(300*3) =1080000 pixels, about one million pixels. If the number of pixels collected is too low, it will reduce the print quality of the image, and if it is too high, it will not improve the print quality.

ppi

ppi (pixels per inch) is the unit of image resolution. The higher the ppi value of the image, the richer the details of the picture, because the pixels per unit area The number is larger, so the pictures taken by digital cameras may be different due to different brands or production times. The common ones are 72ppi, 180ppi and 300ppi. The default is this much (the A710 takes 180ppi. Personally, I feel that this parameter seems to affect Not big, generally no one mentions this). Dpi (dots per inch) refers to the output resolution. For output devices, the output resolution of general laser printers is 300dpi-600dpi, and the printing imagesetter reaches 1200dpi-2400dpi. Common printing is generally between 150dpi and 300dpi. between.

Comparison

ppi and dpi are indeed two concepts, but some things are conventional. The ppi of the picture cannot reflect that the picture can be obtained at the printing shop It is better to go to the store and try it out. If you ask the operator what kind of printing 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 pixels are unrealistically expanded, thus causing the image volume to expand without improving the image quality (the extra pixels are calculated from the difference). The correct way is to first crop your image according to the proportion of the size you need to enlarge. The picture, then fix the pixels of the picture (uncheck the check mark in front of "Redefine the pixels of the picture") and the proportion, adjust the width and height in "Document Size" to be consistent with the expansion size you want, and then it comes out 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 change the " Check "Redefine the pixels of the image" and then change the ppi to 300 or lower.

For more related knowledge, please visit the FAQ column!

The above is the detailed content of What does screen ppi mean?. For more information, please follow other related articles on the PHP Chinese website!