Even if the image is a vector, it is converted to pixels when displayed on the screen. On the first one, we can even see individual pixels!Įverything we see on our computer screen is made of pixels. Both photos were taken at the same distance from the paper. Take a look at the image below, which shows a close photography of the 100 and 300 DPI prints. However, this does not mean that the three images have the same quality! As the actual number of pixels does not change, the quality decreases with lower DPI values. The bigger the DPI ratio, the smaller the printed image is going to be, because of the higher pixel density. The same image (600x300 pixels) was printed on A4 paper using different DPI ratios. For example, take a look at the image below. This means that by changing the DPI ratio of an image, we can change the printed size, although the actual number of pixels remain the same.

With the naked eye we cannot normally perceive this, but the macro photography below shows how very few ink dots are needed for each pixel. In fact, the printer usually needs a higher number of dots to represent a single colored pixel, because of the way the colors are mixed. But this doesn’t mean that the printer is going to “draw” 300 points on the paper for every inch. Usually, for a quality print, we need about 300 DPI, meaning that an image the size of an A4 paper should count 2480x3507 pixels. We can imagine DPI as the number of pixels which would be needed for one inch (2.54 cm) of printed paper. As the pixel is the smallest unit of a digital image, it doesn’t really exist outside digital screens! Naturally, when printing an image, we can measure its size, but, to determine it, the printer makes use of a ratio which is called dots per inch, or simply DPI. The only reasonable answer for this question is “It depends”.

How to determine dpi