画質を損なわずに画像を圧縮する方法

Image compression is essential for fast-loading websites and efficient storage. The key is understanding the difference between lossy and lossless compression.

Lossy vs Lossless Compression

Lossy compression reduces file size by permanently removing some image data. JPEG uses lossy compression, which works well for photographs. At quality levels above 80%, the difference is usually invisible to the human eye.

Lossless compression reduces file size without any data loss. PNG uses lossless compression, making it ideal for graphics, screenshots, and images with text.

Best Practices

1. Use WebP format - WebP provides 25-35% better compression than JPEG at equivalent quality

2. Set quality to 80-85% - This sweet spot offers significant size reduction with minimal visible difference

3. Resize before compressing - Don't compress a 4000px image if you only need 1200px

4. Use batch processing - Tools like OptiPix let you compress multiple images at once

When to Use Each Format

Try our Image Compressor to compress your images right in the browser with zero uploads.

Need to convert formats as well? Our Format Converter handles JPEG, PNG, WebP, and HEIC — also in your browser.