What Is Resolution? A Simple Guide to the Basics

Haru

When you first try to wrap your head around resolution, the whole topic can feel a little overwhelming. Let’s start with the basics and walk through what resolution actually is.

Let’s start with pixels

A pixel is one of the tiny dots that make up an image.
Pixels of all different colors come together to form the images we see.

A photo of a cat sleeping on a pink blanket, with one part magnified in a circle to show that the image is built from a grid of square pixels.

So what is resolution?

It’s how crisp and detailed an image is.
In other words, how densely pixels are packed into the image.

ppi and dpi are units of resolution

ppi (pixels per inch)
dpi (dots per inch)
These are the units used to describe image resolution.
* Strictly speaking, ppi refers to digital resolution and dpi refers to print output resolution, but in everyday use they’re treated as almost the same, so you don’t really need to worry about telling them apart.

They tell you how many pixels (or dots) fit along a one-inch line (25.4 mm).

A diagram comparing pixel density at 10 ppi and 30 ppi. On the left, a coarse 10×10 grid shows 10 ppi; on the right, a fine 30×30 grid shows 30 ppi. The higher the number, the higher the density.

The higher the number, the denser the pixels and the sharper the image

Here’s the same image at three different resolutions: 30, 72, and 300 ppi.
As you can see, even when the dimensions are identical, the version with more pixels naturally looks finer and sharper.

Three versions of the same illustration of a girl eating watermelon, lined up side by side to compare resolutions. The left one is 30 ppi and looks coarse, the middle is 72 ppi, and the right is 300 ppi and looks crisp and detailed.

Summary

Resolution is about how densely pixels are packed together.
The more there are, the finer and sharper the image looks.
ppi and dpi are units of resolution: 300 ppi means 300 pixels lined up along one inch.

#printing #resolution