How to Preserve Image Quality During File Conversion

Image quality loss during conversion is a common concern. Understanding what causes quality degradation and how to minimize it helps you maintain the best possible results when converting between formats.

Understanding Quality Loss

Lossy vs Lossless Compression

• Lossy (JPG, WebP lossy) - Discards data to reduce size, quality decreases
• Lossless (PNG, WebP lossless, TIFF) - Reduces size without losing data

Generation Loss

Each time you open, edit, and save a lossy format, quality degrades further. This is called "generation loss" - like making a photocopy of a photocopy.

How to Preserve Quality

1. Work with Lossless Source Files

• Keep master copies in PNG, TIFF, or RAW format
• Only convert to lossy formats as a final step
• Never use JPG as your working format

2. Use Appropriate Quality Settings

• JPG: 85-95% for high quality, 70-84% for web
• WebP: 80-90% equals JPG at higher settings
• PNG: Always lossless, no quality setting

3. Avoid Multiple Conversions

Convert once from source to final format. Each lossy conversion compounds quality loss.

4. Convert at Original Resolution

Resize separately from format conversion. Combining operations can introduce additional artifacts.

5. Match Format to Content

• Photos → JPG or WebP (lossy is fine for organic images)
• Graphics/logos → PNG or SVG (lossless preserves sharp edges)
• Screenshots → PNG (text stays crisp)

Quality-Preserving Workflow

1. Capture/create images at highest quality possible
2. Store originals in lossless format (master files)
3. Edit master files, save as lossless
4. Convert to lossy only for final distribution
5. Keep masters for future re-exports

Format-Specific Tips

Converting to JPG

• Start from PNG/TIFF for best results
• Use quality 90+ for archival, 80-85 for web
• Chroma subsampling: 4:4:4 for quality, 4:2:0 for smaller files

Converting to PNG

• No quality loss from any source format
• File size depends on image complexity, not quality setting
• Use PNG-8 for simple graphics (256 colors) to reduce size

Converting to WebP

• Lossy WebP at 85% ≈ JPG at 90%
• Lossless WebP is smaller than PNG with identical quality