There are many terms, factors and issues that are confusing in digital images, but surely Surely the one which causes the most trouble is pixels per inch.
First of all, we should clarify the abbreviation that is usually given to this feature of the digital image. “Pixels per inch” is abbreviated with the acronym PPI. What is wrong is to call it DPI, because this means Dots Per Inch, and refers to the resolution of a printer.
Be careful: Some programs such as Photoshop, by default, are set to automatically resize the image when you change the resolution setting PPI to maintain the same print size after the change: it adds more pixels (invented) when we increase the image resolution, or eliminates part of them if we reduce the resolution.
Thus, the concept of "resolution " is always linked to the size or format in which the image is displayed. An image can be printed with 300PPI on paper with 15x25 cm and it will have good photo quality. However, the same image could be printed as large as to cover a building if done with a resolution as low as 10 PPI, but obviously it would not have good photo quality (and it wouldn not be necessary becase these print sizes are watched from afar).Finally, we will explain what are the DPI or dots per inch are, and what is the difference between them and the pixels per inch or PPI. The DPI, as we mentioned earlier, indicate the resolution at which a printer prints. What an inkjet printer does is generate a multitude of small dots of color which combine to create the printed image. An image will have more or less resolution depending on how many dots the printer is able to squeeze in an inch. The photo is generally considered to have good quality when the printer reaches 1440 or more dots per inch(DPI).