compression
Ringing artifact
Ringing artifacts are faint halos or ghost edges that appear around high-contrast boundaries in compressed images.
What is Ringing artifact?
Ringing artifacts are compression distortions that create faint halos, ghost edges, or oscillating brightness bands on either side of sharp boundaries in compressed images. These artifacts most commonly appear around dark text on light backgrounds, logos on photographic backgrounds, and any abrupt transition between light and dark areas. Also called edge ringing, mosquito noise, or haloing, these distortions are caused by the mathematical limitations of lossy compression when reconstructing sharp edges from reduced frequency data.
Importance of Ringing artifact
Understanding ringing artifacts is crucial for maintaining professional image quality when compressing photos for web, social media, or email use. Without proper quality settings, your compressed images can develop unsightly halos around text overlays, product edges, or logo elements that make them appear unprofessional and reduce visual clarity. Recognizing JPEG quality ringing helps you choose appropriate compression levels that preserve the clean edges essential for business graphics and marketing materials.
Ringing artifact in Practice
When you compress a product photo containing a company logo at JPEG quality 65, ringing artifacts typically manifest as light or dark halos approximately 1-2 pixels wide around the logo's edges. These ghost edges become particularly visible when the logo sits on a contrasting background — for example, white text on a dark product surface. The artifacts compound if the image undergoes double compression, such as when you upload a pre-compressed JPEG to Instagram, which re-encodes it at approximately quality 85.
Ringing artifact Best Practices
- → Use JPEG quality 85 or higher when compressing images containing text, logos, or sharp geometric elements.
- → Choose PNG or WebP lossless for graphics with hard edges to completely eliminate ringing artifacts.
- → Avoid double compression by starting with uncompressed source files when possible.
- → Preview compressed images at 100% zoom to check for halos around high-contrast boundaries before publishing.
Example of Ringing artifact
Related Terms
Frequently Asked Questions
What is ringing artifact in image compression?
Ringing artifacts are faint halos or ghost edges that appear around high-contrast boundaries in compressed images, most commonly seen around text, logos, or sharp edges. They're caused by the mathematical limitations of lossy compression algorithms when trying to reconstruct sharp transitions from reduced frequency data. These artifacts appear as light or dark bands oscillating on either side of edges, particularly visible around dark text on light backgrounds.
How do you fix ringing artifacts in JPEG images?
You fix ringing artifacts by using higher quality settings during compression — typically JPEG quality 85 or above for images containing text or logos. For complete elimination, switch to lossless formats like PNG or WebP lossless for graphic elements. If ringing is already present, you'll need to re-compress from the original uncompressed source file at a higher quality setting.
Why do compressed images have halos around text and logos?
Compressed images develop halos because lossy compression algorithms cannot perfectly reconstruct sharp edges from limited frequency data. When JPEG compression quantizes high-frequency components needed for sharp transitions, the decoder creates oscillating waves instead of clean edges. These mathematical overshoots appear as visible halos or ghost edges, particularly around high-contrast boundaries like black text on white backgrounds.