Image Converter
JPG to PNG Converter
Convert JPG images to PNG format instantly in your browser. No upload, no account, completely free.
Image Compressor
Image compression reduces file size by re-encoding pixel data at a lower quality level. The compressor accepts JPG, PNG, and WebP files, applies lossy compression at the quality you choose, and shows the exact file size reduction before you download the result. No file leaves your browser.
How Lossy Image Compression Works
JPEG and WebP compression use transform-based encoding that decomposes the image into frequency components. High-frequency detail — fine texture, noise, and rapid colour transitions that human vision processes less precisely than broad shapes and colour regions — is quantised more aggressively at lower quality settings. The encoder discards imperceptible detail and represents the remaining information more efficiently.
The perceptual effect of compression becomes visible at different thresholds depending on image content. Photographs with sky, skin, and gradients show artefacts at quality settings below 65 to 70. Images with hard edges, text, flat colour, and high-contrast patterns show compression artefacts at higher quality settings because the block boundaries used by the encoder conflict with the image’s precise geometry.
Quality Setting Guide
| Quality range | Use case | Typical size reduction |
|---|---|---|
| 85 to 95 | High-quality web assets, product images, portfolio work | 40 to 60% |
| 70 to 85 | Blog images, social media, general web use | 60 to 75% |
| 55 to 70 | Thumbnails, preview images, background assets | 75 to 85% |
| Below 55 | Placeholder images, heavily degraded previews | 85 to 95% |
PNG Compression Behaviour
PNG is a lossless format — the canvas encoder cannot reduce a PNG’s file size through lossy compression without changing its format. When you compress a PNG file, the compressor outputs WebP instead of PNG. WebP’s lossy encoder achieves significant size reductions while preserving visual quality that PNG’s lossless encoding cannot match at the same file size.
If you need to keep the PNG format and reduce file size, the effective approaches are reducing pixel dimensions (using the Image Resizer) or converting to indexed colour with reduced palette depth using a dedicated PNG optimiser.
Before and After Size Display
The compressor shows the original file size, the compressed output size, and the percentage reduction after processing. This lets you compare quality against savings and re-compress at a different quality setting if the tradeoff is not acceptable before committing to the download.
How the Compressor Works
The image is decoded by the browser’s native codec and drawn to an in-memory canvas element at its original pixel dimensions. The canvas is then encoded in the output format at the quality level you set. The compressor reports the difference between the original file size and the size of the encoded output, then offers the compressed file for download. Processing runs entirely in the browser tab.