What Is a Pixel ?

A pixel, short for "picture element," is the fundamental unit of a digital image. It is the smallest controllable element that displays or represents color and information in a digital display or image sensor.

A pixel, also known as a picture element (pix = picture, el = element), is the smallest adjustable point of a rasterized image. Each pixel can take on properties of over a million different colors—and when grouped together, they can portray an unlimited range of shapes and images. Essentially, pixels are the building blocks of the digital world, allowing designers to manipulate and set them to specific coordinates to bring an image to life.

In visual design, it is important to understand the overall structure of a pixel and how it can be manipulated to benefit the quality of your designs. To avoid common problems like pixelation and decreased web page loading speeds, let’s take a closer look at a single pixel and answer some important questions that will help guide you as you begin to work with pixels.

Pixels are typically arranged in a grid pattern, forming a two-dimensional array. Each pixel can emit or represent different colors and shades, depending on the technology used. In color displays, pixels often consist of subpixels, typically red, green, and blue (RGB), which can combine to create a wide range of colors through additive color mixing.

What is a pixel’s size?

When working with images, there are two key dimensions to consider as you determine the size of their pixels: The height and width of the image and the pixels per inch (PPI). The height and width measure the overall size of your image, whereas the PPI is the number of pixels that cover each 1×1-inch square of the image. A higher PPI means a greater pixel density, which will give you a higher resolution image. A lower PPI will do the opposite, making the image a lower resolution, which means it appears more pixelated.

The number of pixels in an image is referred to as its resolution. The higher the resolution, the more pixels there are, and the sharper the image will be. For example, a 1080p image has a resolution of 1920 x 1080 pixels, while a 4K image has a resolution of 3840 x 2160 pixels.

What you need to know about pixels!

Although pixels are small in nature, there are many important factors to consider when working with them to ensure they properly display on your design or artwork. Three of these factors are responsive web design, pixel density, and color information.

Responsive web design

When designing a web page, you will have to take into account the variety of screen sizes and devices that will be used to view each page of the website. Responsive web design allows designers to adjust the web design grid and how their web page appears on devices like desktop monitors, tablets, and smartphones.

Pixel density

As we touched on earlier, pixel density is a key component to ensuring your image is as crisp as possible, giving it that high-resolution, polished look. However, a high pixel density combined with the overall size of the image itself will increase the image’s file size, which could negatively impact how quickly it loads on a web page. Rather than increasing your image’s PPI to the highest possible density, it’s best to try different increments to find the best image size and PPI for your particular use case.

Color information

Every pixel within an image stores specific color information. For images that will be displayed on a digital screen, pixels will use an RGB (red, green, and blue) color profile. Printed images, on the other hand, use a CMYK (cyan, magenta, yellow, and key/black) color profile and are measured in dots-per-inch (DPI) rather than PPI. In either case, each PPI or DPI will feature a unique color profile—and when placed next to other pixels in a group, they will form an image.

Start building with pixels

Pixels are the building blocks of the digital world. Although they are small, they can significantly impact how our designs are displayed on a variety of different screens and devices. That is why it is important that all designers, especially those participating in a designer-developer collaboration, take the time to understand the functionality of a pixel and how to leverage it to build even our most elaborate designs. When you’re working with pixels, be sure to check your image’s file size and pixelation, as well as make sure that you test out how your images look at multiple breakpoints.