Lossy vs Lossless Compression

Sometimes you're removing empty or useless bits of information so the file reduces in size but it appears exactly the same. This is called lossless compression.

在下列這個表格中，比較了多種影像種類的無損壓縮率，此作者以JPEG XL 來當作比較標準，我們以PNG 為基準來進行換算，當PNG (100%) 為無損壓縮目標時，WebP ...

I've written a new lossy PNG compressor named pngloss. It performs better than lossypng, with lower file sizes and higher visual quality.

pngquant is a PNG compressor that significantly reduces file sizes by converting images to a more efficient 8-bit PNG format with alpha channel (often ... README.md · Changelog · Issues · Pull requests 0

The good news is that PNG can be used as a lossy format and produce files few times smaller, while remaining perfectly compatible with lossless PNG decoders.

pngquant is a command-line utility and a library for lossy compression of PNG images. The conversion reduces file sizes significantly (often as much as ... Pngquant2 vs Photoshop... · Pngquant Installation · Running from PHP

PNG is lossless by design, there's no lossy PNG. All you can do is some lossy preprocessing before saving it as PNG, as converting a true colour image to a ...

PNG is always lossless. It uses Deflate/Inflate algorithm, similar to those used in zip programs. Deflate algorithm searches repeated sequences ...

Free online image optimizer for faster websites! Reduce the file size of your AVIF, WEBP, JPEG and PNG images while preserving the image quality. Developer API · Web Page Image Analyzer · Third-Party Solutions · API Reference

There is pngquant. But it works by reducing number of colors which results in very noticeable loss in quality. ImageAlpha has only mac version.