What is the difference between lossy and lossless image compression?

Lossy compression (like that used for JPEG and WebP at lower qualities) reduces file size by permanently discarding some image data that is less perceptible to the human eye. This can achieve very small file sizes but may result in some quality degradation if overdone. Lossless compression (used for PNG and high-quality WebP) reduces file size by optimizing data without throwing any information away, so the original quality is perfectly preserved, though file sizes are typically larger than with lossy methods.

Which format is best for image compression: JPEG, PNG, or WebP?

It depends on the image type and use case. For photographs, JPEG or WebP (lossy) at a quality setting around 75-85 often provides the best balance of size and quality. For graphics with sharp lines, text, or transparency, PNG (lossless) or WebP (lossless) is generally preferred. WebP often provides better compression than both JPEG and PNG for similar quality levels and is excellent for web use.

How does this tool compress PNG files if it's lossless?

For PNG files, our tool performs a re-encoding process. While the HTML Canvas API used for this doesn't offer advanced PNG-specific optimization algorithms like some standalone tools (e.g., OptiPNG, pngquant), it can sometimes result in a slightly smaller file if the original PNG was not efficiently encoded, or if converting from a less optimized format like BMP. The process remains visually lossless for PNG output.

Will using this online image compressor change my image's dimensions (width/height)?

No, our Image Compressor tool focuses solely on reducing the file size (in bytes, KB, or MB) through compression techniques. The pixel dimensions (width and height) of your image will remain unchanged. If you need to change the dimensions, please use our 'Image Resizer' tool.

Is it safe to compress images online using this tool?

Yes, this is a secure image compressor. All processing happens directly within your web browser. Your images are not uploaded to our servers, ensuring your privacy and data security. It's also a free image compressor with no registration required and no watermarks applied.

Can I use this tool to compress large files or for batch image compression?

This tool is designed for single image compression and generally works well with reasonably sized images (e.g., up to 10-15MB, depending on browser performance). For compressing multiple images at once (batch image compressor functionality), please check out our 'Bulk Image Converter' which might offer compression options or a dedicated 'Bulk Image Compressor' tool if available.