Pixel Density (PPI/PPM)

Understanding Pixel Density

Pixel density is the key metric connecting physical LED wall specifications to perceived image quality. Understanding density helps optimize the balance between quality and budget.

Measuring Pixel Density

**Pixels Per Square Meter (PPM):** Standard industry measurement:

• Formula: 1,000,000 ÷ (pitch in mm)²
• 1.2mm pitch: 694,444 PPM
• 2.5mm pitch: 160,000 PPM
• 4.0mm pitch: 62,500 PPM

**Pixels Per Inch (PPI):** Common in display industry:

• Formula: 25.4 ÷ pitch in mm
• Less intuitive for LED walls
• Borrowed from monitor specifications

Density vs. Pitch Relationship

Pixel density increases exponentially as pitch decreases:

| Pitch | Pixels/m² | Relative Cost | |-------|-----------|---------------| | 4.0mm | 62,500 | 1x | | 2.5mm | 160,000 | 2-3x | | 1.5mm | 444,444 | 5-8x | | 0.9mm | 1,234,568 | 15-25x |

Practical Applications

**Close Viewing (3-6 feet):**

• Control rooms
• Broadcast studios
• Retail displays
• Recommended: 1.2-1.9mm (280,000-700,000 PPM)

**Medium Viewing (6-15 feet):**

• Conference rooms
• Corporate events
• Houses of worship
• Recommended: 2.0-3.0mm (110,000-250,000 PPM)

**Far Viewing (15+ feet):**

• Concerts
• Stadiums
• Outdoor signage
• Recommended: 3.0mm+ (under 110,000 PPM)

Resolution Calculation

To find total wall resolution:

**Width in Pixels:** Wall width (mm) ÷ pixel pitch (mm)

**Height in Pixels:** Wall height (mm) ÷ pixel pitch (mm)

**Example:** 4000mm × 2250mm wall at 2.5mm pitch:

• Width: 4000 ÷ 2.5 = 1600 pixels
• Height: 2250 ÷ 2.5 = 900 pixels
• Total: 1600 × 900 = 1,440,000 pixels

Cost Implications

Higher density = exponentially higher cost:

• More LEDs per panel
• More driver ICs
• More complex manufacturing
• Lower yields

**Budget Optimization:** Match density to actual viewing conditions. Over-specifying wastes budget without visible benefit.

Quality Considerations

**Consistency:** Higher density makes inconsistencies more visible:

• Color uniformity more critical
• Dead pixels more noticeable
• Calibration more important

**Content Requirements:** Higher density enables:

• Finer detail display
• Smaller text legibility
• Better image reproduction

Specification Best Practices

**Site Survey:** Measure actual viewing distances before specifying density.

**Content Analysis:** Review typical content—text-heavy content needs higher density.

**Budget Balance:** Often better to have larger lower-density wall than smaller high-density wall.