Then there’s always the possibility that you’re taking a digital image to a printing shop, and they request that a photo is converted to 300 DPI, as this is the minimum quality for artwork if you want a decent printing outcome. Perhaps you took a photograph in very high quality and you need to reduce the DPI and thus the file size to make it easier for editing? Or maybe you are uploading a file online and the system will only allow a certain DPI. When editing a picture, you may need to change the DPI for numerous reasons. In simple terms, the more dots (or pixels) per inch and the higher the DPI (or PPI) the higher the overall image quality as well as the bigger the file size. It, therefore, controls one of the most important things in photography: the quality of the picture. Nevertheless, both DPI and PPI refer to every tiny dot or pixel in a picture and defines how many of these dots are in every square inch within a certain sized photo.

While the two terms aren’t technically interchangeable, they both represent the same thing: the resolution of an image. It’s a specification that originated in the print industry, however, it has been carried over to the digital world and thus is often confused with PPI or “pixels per inch”. In case you’re unfamiliar - or need reminding - DPI stands for “dots-per-inch”.

If you’ve ever needed to resize an image, chances are you’ve had to make yourself familiar with the term “DPI”. When and why you should use an image DPI converter

How to find dpi of pdf image