Pixels are the individual building blocks of every digital photograph and most other digital images. In addition to pixels in a digital image, pixels can refer to pixels in a digital display, a digital camera sensor, and other devices. But, in this article, we’ll mainly be talking about the pixels in digital images.
What is Pixel?
Let’s first understand what is pixel. The word ‘pixel’ was invented by combining the words ‘picture element’. You can think of the pixels in digital images as colored squares. The images you see on screens usually have hundreds of thousands (and often millions) of pixels — when enough of these colored squares are placed next to one another and displayed at a small enough size, you see continuous images instead of individual pixels. Unless you zoom an image far enough to see the pixels, in which case they appear as colored squares.
How Big is a Pixel?
Pixels themselves don’t really have a size. While physical units like inches or centimeters have an exact, real-world size, a pixel is more of a logical unit than a physical one. However, the pixels of digital images are most often displayed at a size so small as to not be visible, so they usually exist as very small elements.
How are Pixels Related to Physical Units?
After understanding what is pixel, the next question that comes to one’s mind is how is it measured. Although pixels don’t have their own size, their relationship to physical units becomes important when you want to print an existing image. Or if you want to create a new image to be printed at a particular size. For example, if you’d like to print an image at 6 inches wide and 4 inches tall, that says nothing about how many pixels it has or should have.
At this point, it’s important to make sure that, just like when displaying an image on a screen, the individual pixels are small enough to not be visible. The standard for high-quality prints is to print 300 pixels per inch of a page. How many pixels should fit into an inch is called the resolution of the image? And with a resolution of 300 pixels per inch (PPI), 6 inches are now equal to 1,800 pixels and 4 inches are 1,200 pixels.
How Do Pixels Come to Exist?
Pixels can come to exist in a few different ways. For example, digital cameras have sensors made up of light-detecting pixels. When you press the shutter, the sensor captures the subject you’re photographing. The information detected by each of the pixels of this sensor is translated into the pixels of a digital image. Instead of capturing a photo, if you create a new image in Pixelmator Pro, the first step is setting its size. Therefore, you immediately say how many pixels you’d like your image to have. So all digital images start as collections of pixels and as long as they exist in digital form, they continue being collections of pixels.
How Do Pixels Work?
Pixels are the vehicle for transforming binary code data into an image on a screen. Each pixel in an RGB monitor is sent a piece of code that tells it how to display a certain color. Because each pixel has red, green, and blue lighting elements, the code is made up of a triplet of eight-digit numbers written in binary code. This tells each of the three color elements at what intensity to display, and when all three colors are combined, they display the desired color. Each pixel displays one color, and the colors together make an image.
Resolution vs Pixel Density
When talking about image or screen quality, the term resolution is often used. Screen resolution can be defined as the number of pixels on a screen. For example, a 13-inch Macbook Air has a resolution of 2560 x 1600, which means that the screen is made up of over 4,000,000 pixels. The higher the resolution, the higher the image quality.
While the resolution is important to consider when measuring screen quality, it is also important to consider the pixel density. Pixel density is either measured in PPI (pixels per inch) or PPC (pixels per centimeter). For example, if you look at a photo on an iPhone and a movie screen, both with 1792 x 828 resolution, the iPhone image will have a better quality because the PPI is higher on the iPhone screen. When the picture is blown up on a movie screen with the same resolution as the iPhone, the image will be pixelated.