pdf-compress

## Image Compression Settings
 
### Resolution Reduction
| Target | DPI | Use For |
|--------|-----|---------|
| Screen | 72 | Web viewing |
| eBook | 150 | Digital documents |
| Print-basic | 200 | Office printing |
| Print-quality | 300 | Professional print |
| Original | N/A | No reduction |
 
### Format Conversion
| From | To | Savings | Quality Impact |
|------|-----|---------|----------------|
| TIFF | JPEG | 70-90% | Some loss |
| PNG | JPEG | 50-80% | Some loss |
| BMP | JPEG | 90%+ | Some loss |
| JPEG | JPEG (recompress) | 20-50% | Cumulative loss |
 
### Quality Levels
| Setting | JPEG Quality | Visual Impact |
|---------|--------------|---------------|
| Maximum | 90-100 | Imperceptible |
| High | 75-89 | Minimal |
| Medium | 50-74 | Noticeable on zoom |
| Low | 25-49 | Visible artifacts |

## Additional Optimizations
 
### Font Optimization
- [ ] Subset fonts (remove unused characters)
- [ ] Convert to standard fonts where possible
- [ ] Remove duplicate font instances
 
### Structure Optimization
- [ ] Remove unused objects
- [ ] Clean up metadata
- [ ] Linearize for web (fast web view)
- [ ] Remove bookmarks (optional)
- [ ] Remove comments/annotations (optional)
 
### Content Removal (Caution)
- [ ] Remove hidden layers
- [ ] Remove JavaScript
- [ ] Remove form fields
- [ ] Remove embedded files

## PDF Compression Report
 
### File Summary
| Metric | Before | After | Change |
|--------|--------|-------|--------|
| **File Size** | 45.2 MB | 8.7 MB | -81% |
| **Pages** | 120 | 120 | - |
| **Images** | 89 | 89 | - |
 
### Compression Applied
| Technique | Savings |
|-----------|---------|
| Image downsampling (150 DPI) | 28.5 MB |
| JPEG compression (75%) | 5.2 MB |
| Font subsetting | 1.8 MB |
| Object cleanup | 1.0 MB |
| **Total Savings** | **36.5 MB (81%)** |
 
### Quality Assessment
| Aspect | Rating | Notes |
|--------|--------|-------|
| Text clarity | ⭐⭐⭐⭐⭐ | No change |
| Image sharpness | ⭐⭐⭐⭐ | Slight softening |
| Color accuracy | ⭐⭐⭐⭐⭐ | Preserved |
| Zoom quality | ⭐⭐⭐ | Pixelation at 400%+ |
 
### Recommendations
✅ Suitable for: Email, web, screen viewing
⚠️ Not recommended for: High-quality print, archival

## Compression Strategy: [Document Name]
 
### Current State
- File size: 150 MB
- Pages: 200
- Issue: Too large for email (limit: 25 MB)
 
### Target
- Max size: 20 MB
- Maintain readability
 
### Recommended Approach
1. **Images**: Reduce to 150 DPI, JPEG 70%
   - Expected savings: ~100 MB
2. **Fonts**: Subset embedded fonts
   - Expected savings: ~5 MB
3. **Cleanup**: Remove metadata, optimize structure
   - Expected savings: ~5 MB
 
### Expected Result
- Final size: ~20 MB
- Quality: Good for screen/general use

## Batch Compression Job
 
### Input
- **Folder**: /documents/reports/
- **Files**: 45 PDFs
- **Total Size**: 2.3 GB
 
### Settings
- Compression level: Medium
- Target: Email-friendly (<10 MB each)
- Image DPI: 150
- JPEG quality: 75%
 
### Progress
| File | Original | Compressed | Reduction |
|------|----------|------------|-----------|
| report_q1.pdf | 85 MB | 12 MB | 86% |
| report_q2.pdf | 120 MB | 18 MB | 85% |
| report_q3.pdf | 95 MB | 14 MB | 85% |
| ... | ... | ... | ... |
 
### Summary
| Metric | Value |
|--------|-------|
| Files processed | 45 |
| Total before | 2.3 GB |
| Total after | 380 MB |
| Average reduction | 83% |
| Files under 10 MB | 42/45 |
 
### Large Files (Need Review)
| File | Size | Recommendation |
|------|------|----------------|
| annual_photos.pdf | 25 MB | Split or higher compression |
| tech_diagrams.pdf | 18 MB | Reduce image count |
| charts_hires.pdf | 15 MB | Acceptable |

## Quality Comparison Guide
 
### Image Quality at Different Levels
 
**Original (300 DPI, no compression)**
- Sharp at all zoom levels
- File size: Large
 
**High Quality (200 DPI, JPEG 85%)**
- Sharp at 100-200% zoom
- Minor softening at high zoom
- File size: Medium-large
 
**Medium Quality (150 DPI, JPEG 70%)**
- Good at 100% zoom
- Noticeable softening at 200%+
- File size: Medium
 
**Low Quality (96 DPI, JPEG 50%)**
- Acceptable at 100%
- Pixelation visible
- File size: Small
 
### Text Remains Sharp
Note: Text (when vector) remains crisp at all compression levels.
Only embedded text images are affected.