Lossy vs lossless compression comparison
| Feature | Lossy | Lossless |
|---|---|---|
| Data loss | Yes — some data permanently removed | No — original data fully recoverable |
| File size | Much smaller (5–50× reduction) | Moderately smaller (1.5–3× reduction) |
| Quality | Slight degradation (often invisible) | Identical to original |
| Formats | JPEG, WebP lossy, AVIF lossy | PNG, WebP lossless, TIFF, GIF |
| Best for | Photos, web images, documents | Logos, text, screenshots, medical images |
When to use lossy compression
Lossy compression is ideal when:
- You need to hit a specific file size target (e.g., 200KB for UPSC).
- The image is a photograph with gradual colour transitions.
- You're optimising for web performance (website speed guide).
- The slight quality loss is imperceptible to the viewer.
When to use lossless compression
Lossless compression is better when:
- The image contains text, logos, or sharp edges.
- You need to edit the image multiple times without degradation.
- Pixel-perfect accuracy is required (medical imaging, design assets).
- The image is a screenshot or diagram.
The hybrid approach: WebP and AVIF
Modern formats like WebP and AVIF support both lossy and lossless modes. WebP lossy offers 25–35% better compression than JPEG at equivalent quality. AVIF goes even further with 50% better compression. Use PhotoResizer.in's format converter to easily convert between formats.
Technical Verification & Standards Compliance for Digital Submissions
When uploading photographs, signatures, or official records to government portals, visa processing systems, or recruitment boards, strict automated validation scripts evaluate both visual clarity and physical file parameters. Minor errors—such as non-standard aspect ratios, improper pixel dimensions, high compression artifacts, or unstripped EXIF headers—frequently trigger instant system rejections.
Image Dimension & Aspect Ratio Math
Official forms specify exact physical measurements (e.g., 3.5cm × 4.5cm) or pixel boundaries (e.g., 350×450px). Converting physical units into digital resolution requires applying exact DPI scales: Pixels = (Millimeters / 25.4) × DPI.
Local WebBrowser Compression Engine
PhotoResizer.in uses client-side HTML5 Canvas and WebAssembly algorithms to compress image streams down to specific KB limits (10KB, 20KB, 50KB, 100KB, 200KB) entirely inside your web browser. Visual data never leaves your device.