Though you might not think that image file formats matter, the truth is that different image containers have their own strengths and weaknesses. In the real world, different web media scenarios call for specific formats. The most popular image file formats are JPEG, GIF and PNG. Understanding the differences between file formats as well as the pros and cons of each will help you to choose the right one for any given application.
JPEGs Explained & When to Use Them
Created by the Joint Photographic Experts Group, JPEGs are lossy image files that boast a compression ratio of up to 10:1. This means that you can compress a high-definition image to a fraction of its size without a big drop in quality. JPEGs can support up to 16.7 million colors and are capable of displaying crisp details. The downside is that JPEGs don’t support transparency.
For the most part, JPEGs are used when it’s important to display a range of colors and shading. In other words, they’re perfect for still photos and background gradients but not much else. For instance, they shouldn’t be used for simple graphics, icons or line drawings. While JPEGs can be greatly compressed, they become progressively more blurry each time you shrink them. Consequently, it’s wise to rely on another format for images with limited palettes.
GIFs Explained & When to Use Them
Short for Graphics Interchange Format, GIF is an old standard created in 1987 that uses lossless compression to shrink files. It can support up to 256 different colors using an indexed palette. It also boasts progressive loading, limited transparency and dithering, a process whereby multiple pixels can be merged to reduce the number of colors used in an image. GIF files are limited to 8 bits per pixel, making them incredibly small.
Basically, the GIF file format is best suited to logos, line drawings and simple images like web graphics. Animations that don’t require a high resolution are one of the GIF format’s primary wheelhouses. If graphics don’t need to be scaled, the GIF is usually an appropriate choice. Black-and-white images in particular should be converted to GIFs to cut down on file sizes. Furthermore, images with extremely compact text look best when published as GIFs.
PNGs Explained & When to Use Them
Short for Portable Network Graphics, the PNG file format is meant to be a replacement for GIF. Since it uses lossless compression, PNG can reduce file sizes while allowing for scalability. Much like GIFs, PNG-8 files can use up to 256 colors. Though it can’t be compressed to the same extent as its 8-bit cousin, a PNG-24 file can support a more extensive palette. PNG also supports alpha transparency by default.
For the most part, PNGs are used in situations where a GIF would suffice if alpha transparency and a greater range of color are also required. For instance, many header logos and icons will often be saved in the PNG file format. In addition, the ability to scale makes the PNG perfect for charts and graphs. Other common uses for PNGs are medical images and GIS-related files like maps. If storage space isn’t an issue, they can even be used to replace JPEGs in some scenarios.
Knowing Is Half the Battle
Generally speaking, settling on an appropriate image file format is easy. Use JPEGs when you require excellent image quality but want to save on space. Use GIFs when low resolution isn’t an issue or if you want to display animations. Use PNGs for logos, icons and any images that may need to be resized. With those guidelines in mind, remember that every situation is unique and must be evaluated on a case-by-case basis.