Study: WebP at Quality 80–85 Beats High-JPEG Settings for Photos

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A compression study tested 24 images from the standard Kodak reference suite, encoding each as JPEG and WebP across quality levels 20 to 95 and scoring results using the SSIM structural similarity metric. The findings show that most perceptible quality is gained early in the compression curve, with diminishing returns at higher settings — raising JPEG quality from 85 to 95 nearly doubles file size for an SSIM improvement of just 0.025. WebP consistently outperformed JPEG, delivering roughly 30% smaller files at equivalent perceived quality. Lossless formats cost approximately seven times the size of a quality-85 JPEG, making them impractical for most photographic use cases. Researchers recommend quality 80–85 in WebP as the practical sweet spot, while noting that the ideal setting varies by image content and is best determined through live preview rather than a fixed number.

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