JPEG and PNG are common formats for digital web graphics, but they are not created equal. Knowing the ins and outs of each image format can inform your web design decisions. JPGs offer smaller file sizes for photos, while PNGs deliver pristine, sharp quality, perfect for logos and detailed images such as line drawings.
Explore the nuances of PNG vs. JPG and how to choose the correct file format for best presenting your digital images.
What are JPGs?
JPG, short for Joint Photographic Experts Group, is a file type widely used by digital photographers. It was developed in 1992 when the internet was in its infancy and transfer speeds were slow. It applies a compression algorithm used to reduce the file size of large images so they can be delivered over the internet quicker. It also had another major advantage: taking less storage space on hard drives. There are two common naming conventions for the format—JPG and JPEG, used as a file extension—but there’s no difference between the two.
JPG uses a lossy compression method. Some image data is discarded to reduce file size while preserving image integrity as much as possible. There are different levels of compression you can apply when you export images from the large RAW formats to JPEG. Setting it to the best quality will apply less lossy compression than normal quality, and the file size will be larger. The JPEG compression process works well for photographs, but has downsides for image files with sharp lines and text-based logos.
What are PNGs?
PNG stands for Portable Network Graphics, a file format designed for web graphics, logos, charts, and illustrations. PNG files were created in 1994 as an alternative to GIFs—the Graphics Interchange Format (which is still popularly used for memes).
PNGs use lossless compression to condense file size. All the image data is preserved during compression, maintaining image quality even after multiple edits. PNG format also supports transparent background, something JPGs can’t do.
RGB vs. CMYK color modes in JPGs and PNGs
RGB stands for the “red green blue” color model used for digital displays. CMYK is the color mode appropriate for the four-color printing process. It stands for “cyan, magenta, yellow, and black.” An accurate CMYK color match is vital for printing high-quality images.
While both PNG and JPEG files support RGB, neither supports CMYK. That means both formats are best for web images on digital displays, not print media.
If you require CMYK color modes, it’s best to use other image formats like PSD (Photoshop Document) or TIFF (Tagged Image File Format).
JPG vs. PNG: What’s the difference?
JPEG and PNG files are both effective at what they do, but they differ in a few important ways:
Lossy compression vs. lossless compression
JPEG files use the lossy compression method, in which bits of image data are discarded to reduce file size while trying to preserve as much image integrity as possible. This can lead to a reduction in image quality over time, especially with repeated editing. You can see this impact when resizing a smaller JPG image to make it larger, for example.
PNG uses lossless compression, preserving all the image data and maintaining image quality regardless of how many times the same image is edited or saved. If you need to maintain the sharpness of the image, PNG is a good choice.
File size
JPGs are great at crunching file size down, making them ideal for web browsers, where fast loading times are a priority. They also take up less space on the hard drive. PNGs, due to their lossless compression algorithm, typically yield larger file sizes, which can have a small impact on load time.
🌟 What image size should you use? Use this cheat sheet to find the best image sizes for your website on mobile and desktop.
Transparency
Transparency is an effect where a background color in the image is designated as invisible, so you can achieve see-through effects when the image is placed on a web page background. The background color of the web page will replace the transparent color.
The PNG format supports transparency, but JPG files do not. This factor makes PNG a better choice for logos designs, icons, and other web design elements that need to be layered smoothly onto different backgrounds.
Animation support
Animated GIFs are one of the other image formats from the early days of the computer, and they’re still popular today thanks to memes.
Are JPGs or PNGs a valid alternative to animated GIFs? JPGs are not a replacement, as they do not support animations. A PNG file itself doesn't inherently support animation, either. But there is an Animated Portable Network Graphics (APNG) extension that supports high-quality, lossless animations with full color and transparency. APNG also supports 24- or 48-bit images and full alpha transparency, which you can’t get with GIFs.
When to use JPG vs. PNG
Choosing between JPG and PNG images depends on how you plan to use them. Take into consideration key factors when choosing file formats for the following:
Web graphics
JPG files are best for photographs on websites where smaller file sizes and faster loading times are important. PNGs are preferable for logos and web graphics requiring sharp lines and edges that can scale.
Image editing
PNG vs. JPEG is a factor to consider if you plan on doing a lot of image editing. PNG is preferred for editing because it retains image quality through multiple edits.
JPEGs can be acceptable for simple edits but not for complex editing because the image quality will degrade with each edit.
Transparent images
Images requiring a transparent background color should be saved as PNGs. JPEGs do not support transparency.
Printing
PNG’s lossless compression delivers higher-quality images for local printing usage, especially for images with text or sharp lines. However, PNG files can’t support CMYK, which is needed to print colors accurately.
The lossy image compression algorithm used by JPG means you’ll be losing quality when it prints. It's not a good choice for professional printing usage.
If high-quality printing is a necessity, forego both formats and use TIFF, PSD, or PDF files.
JPG vs. PNG FAQ
Is PNG better quality than JPG?
PNG generally offers better quality than JPG format because it uses lossless compression, preserving all the image data. JPEG images are useful for photographic representation and when small file sizes are a priority.
What do PNG file formats offer that JPG file formats do not?
PNG’s lossless compression attains higher image quality and adds support for transparent backgrounds. JPG files save space, but it comes at a cost to quality.
Does converting PNG to JPG reduce quality?
Yes, converting a PNG to a JPG will result in some loss of image quality because a JPG image uses lossy compression.
