1.90:1 IMAX Digital

What is 1.90:1 IMAX?

1.90:1 is the standard aspect ratio for IMAX Digital projections. It was introduced in 2008 with the digital IMAX system and is now the dominant format in most IMAX cinemas worldwide.

Mathematically, 1.90:1 is approximately 17:9 – wider than 16:9 (1.78:1), but significantly narrower than the original IMAX ratio of 1.43:1.

Comparison of IMAX Aspect Ratios

Why 1.90:1?

The decision for 1.90:1 was based on practical reasons:

Technical Factors:

• 2K projectors had a native resolution of 2048×1080
• Ratio ~1.90:1 optimally utilizes sensor area
• Compatible with existing digital workflows

Economic Factors:

• Smaller screens possible
• Fits into converted standard cinema auditoriums
• Lower installation costs

The Loss of Height

For films shot for 1.43:1, 1.90:1 means a loss of ~25% of the image height:

Original 1.43:1:

┌─────────────────────┐
│ │
│ │
│ FULL FRAME │
│ │
│ │
└─────────────────────┘

Cropped to 1.90:1:

┌─────────────────────┐
│▓▓▓▓▓CROPPED▓▓▓▓▓│
│ │
│ VISIBLE │
│ │
│▓▓▓▓▓CROPPED▓▓▓▓▓│
└─────────────────────┘

Open Matte vs. Cropped

Directors like Christopher Nolan shoot using the Open Matte technique:

• Full 1.43:1 image area is captured
• Composition is optimized for both ratios
• 1.43:1 shows more image (not less)
• 1.90:1 is the "cropped" standard

In "Oppenheimer," for example, IMAX 15/70 viewers see more sky and ground than digital IMAX viewers.

ARRI Alexa 65 and 1.90:1

The ARRI Alexa 65, certified for IMAX, records natively in 1.90:1:

• Sensor: 54.12 × 25.58 mm
• Native Ratio: ~2.11:1
• IMAX Mode: 1.90:1

These cameras cannot achieve true 1.43:1 – only the old film cameras offer the full IMAX ratio.

The "Expanding Ratio" Technique

Many modern IMAX films switch between aspect ratios:

Example "Dune" (2021):

• Dialogue scenes: 2.39:1 (Cinemascope)
• Action scenes: 1.90:1 (IMAX Digital)
• True IMAX cinemas: 1.43:1 (only in selected scenes)

The image "opens up" for important moments – a visual effect that is impactful in the cinema.

1.90:1 in Practice

Advantages:

• Widely available (~1,500 screens)
• More affordable for cinema operators
• Easy digital distribution

Disadvantages:

• Loss of IMAX immersion
• Similar to home theater aspect ratio
• Little difference to Premium Large Format (PLF)

Conclusion

1.90:1 is a compromise between the immersive 1.43:1 original and the practical requirements of digital distribution. For filmmakers, it means composing for two target formats – the full IMAX and the reduced digital IMAX.