Differences between JPEG and PNG

JPEG vs. PNG

JPEG (Joint Photographic Experts Group) and PNG (Portable Network Graphics) are two of the most common raster image file formats used on the internet. Both formats are capable of handling images with millions of colors. The primary differences between them lie in their compression methods, which affects file size and image quality, and their support for transparency. The choice between JPEG and PNG typically depends on the type of image and its intended use.

Comparison Table

Category	JPEG	PNG
Full Name	Joint Photographic Experts Group	Portable Network Graphics
Compression Type	Lossy	Lossless
Transparency	Not supported	Supports full alpha transparency
Best For	Photographs and complex images with many colors	Logos, icons, illustrations, and images with sharp edges or text
File Size	Generally smaller	Generally larger
Editing	Quality degrades with each save (generation loss)	Retains full quality after multiple saves

Venn diagram comparing Differences between JPEG and PNG

Compression

The most significant difference between JPEG and PNG is how they compress image data. JPEGs use a lossy compression method, which means that some image data is permanently discarded to reduce the file size. This technique allows for significant reductions in file size, which is beneficial for web page loading times. However, this can result in compression artifacts, which may appear as blurriness or blocky textures, especially if the image is heavily compressed or saved multiple times.

PNG, in contrast, uses lossless compression. This method retains all of the original image data, ensuring that the quality of the image remains identical to the original, no matter how many times the file is saved. The trade-off for this preservation of quality is that PNG files are typically larger than their JPEG counterparts.

Transparency

Another key distinction is transparency support. The PNG format includes an alpha channel, which allows for varying levels of transparency, from fully opaque to completely transparent. This makes PNG the ideal format for images like logos or icons that need to be placed over different backgrounds without a solid-colored box around them. JPEGs do not support transparency; any transparent areas in an original image will be filled with a solid color, usually white, when saved as a JPEG.

Use Cases

Due to its efficient compression, JPEG is the standard format for digital photography and for displaying complex, colorful images on the web where smaller file sizes are a priority. Its main drawback is the loss of quality that occurs with compression and repeated edits.

PNG is the preferred format for graphics where clarity and sharpness are essential, such as logos, line art, and images containing text. Its lossless compression preserves fine details and sharp edges that can be degraded by JPEG compression. The support for transparency also makes it indispensable for web design and graphic overlays. For images that will undergo multiple rounds of editing, working with a PNG file prevents the cumulative quality degradation associated with the JPEG format.