JPEG vs PNG Compression: How They Differ
JPEG uses lossy compression optimized for photographs. It discards image data that humans typically do not perceive, achieving dramatic file size reductions. A 10MB uncompressed photo might become 500KB with minimal visible difference.
PNG uses lossless compression, preserving every pixel exactly. This makes PNG ideal for screenshots, graphics with text, and images needing transparency. However, PNG files for photos are typically much larger than equivalent JPEGs.
Finding the Right Quality vs Size Balance
JPEG quality settings range from 0-100. Quality 80-90 looks nearly identical to the original while cutting file size significantly. Quality 60-70 shows subtle artifacts but may be acceptable for thumbnails or quick previews.
Test different quality levels for your specific image. Photos with smooth gradients (sky, skin) show compression artifacts more readily than busy textures. Adjust quality based on image content and intended use.
Web Performance and Core Web Vitals
Google's Core Web Vitals measure user experience, with Largest Contentful Paint (LCP) particularly affected by image file sizes. Large hero images that take seconds to load hurt your page score and user satisfaction.
Aim for images under 200KB when possible. Use responsive images to serve smaller files to mobile devices. Consider WebP format for additional savings on browsers that support it.
Lossless vs Lossy: When Each Makes Sense
Lossy compression permanently removes data to shrink files dramatically. Use for web images, email attachments, and social media where slight quality loss is acceptable.
Lossless compression preserves every detail. Use for source files, archival storage, and images requiring future editing. FormatWiz processes both approaches locally in your browser, keeping your images private throughout.