Understanding Lossy vs Lossless Compression
When using an Image Compressor, you must fundamentally decide between Lossy and Lossless compression. Choosing the wrong algorithm can either bloat your website or destroy the readability of your graphics.
Lossless Compression
Lossless compression reduces file sizes by identifying patterns and redundancies in the data, mathematically abbreviating them.
When a lossless image (like a PNG) is decompressed by the browser, it is mathematically identical to the original file. Every single pixel is perfectly reconstructed.
- Best For: Screenshots, logos, typography, line art, and medical imaging.
- Tradeoff: Minimal file size reduction (usually only 10-20%).
Lossy Compression
Lossy compression permanently discards data that the algorithm determines is imperceptible to the human eye. It groups similar colors together and averages them out.
When a lossy image (like a JPEG) is saved, data is destroyed forever. If you repeatedly save a JPEG, it will suffer from "generation loss," resulting in heavy blocky artifacts.
- Best For: Complex photographs with millions of colors, gradients, and web hero banners.
- Tradeoff: Permanent quality degradation in exchange for massive file size reductions (up to 90%).