IIQ Format Guide

Available Conversions

About IIQ Format

IIQ is Phase One's proprietary RAW image format used by their medium format digital camera systems, including the IQ series digital backs (IQ1, IQ2, IQ3, IQ4) and XF/XT camera bodies. It stores unprocessed sensor data at 16-bit depth, preserving maximum image quality and editing flexibility from sensors ranging from 40 to 150 megapixels. IIQ files contain the complete, unprocessed data captured by Phase One's industry-leading CCD and CMOS sensors, along with comprehensive metadata about camera settings, lens information, and shooting conditions. The format is the standard for commercial photography, fashion, advertising, and fine art reproduction, where absolute image quality and color accuracy are paramount. IIQ files are typically processed in Capture One, Phase One's own RAW processing software, which provides optimized rendering for Phase One sensor characteristics.

History of IIQ

Phase One, founded in Copenhagen, Denmark in 1993, has been at the forefront of medium format digital imaging since the company introduced its first digital camera back in 1998. The IIQ format evolved as Phase One's proprietary RAW standard, replacing earlier formats used in their P-series digital backs. The name "IIQ" derives from "Intelligent Image Quality," reflecting Phase One's focus on delivering the highest possible image fidelity. The format matured alongside Phase One's sensor technology: from the early 39-megapixel P45+ backs through the revolutionary 80-megapixel IQ180 (2011), the 100-megapixel IQ3 100MP (2016), and the current 150-megapixel IQ4 150MP (2018) which uses a backside-illuminated CMOS sensor. Phase One's acquisition of Mamiya in 2009 expanded their camera body lineup, and the IIQ format became the standard across both the Phase One XF system and the Mamiya-derived 645 platform. Throughout this evolution, IIQ has maintained backward compatibility while incorporating new features like lossless compression options (IIQ-L for lossless, IIQ-S for sensor-optimized). The format remains tightly integrated with Capture One software, which Phase One develops specifically to maximize the quality potential of their sensors and the IIQ format.

Key Features and Uses

IIQ files store unprocessed, linear sensor data at 16-bit depth, providing an extraordinary dynamic range of approximately 15 stops in the latest IQ4 digital backs. The format preserves the full tonal and color information captured by Phase One's large medium format sensors (typically 53.4 x 40.0 mm or 53.7 x 40.4 mm), which are significantly larger than full-frame 35mm sensors and capture correspondingly more light and detail. IIQ supports both uncompressed and lossless compressed variants: IIQ-L (lossless) reduces file sizes by approximately 30-40% without any data loss, while the standard uncompressed IIQ preserves the raw sensor readout exactly as captured. The format includes extensive metadata covering all camera and lens settings, GPS coordinates, orientation data, and Phase One's proprietary lens correction profiles for their Schneider Kreuznach optics. IIQ files from the IQ4 150MP produce images at 14204 x 10652 pixels, resulting in files of 150-300 MB per image depending on compression settings and scene complexity.

Common Applications

IIQ is the standard format for the highest echelon of commercial photography, where Phase One systems dominate due to their unmatched resolution, color accuracy, and dynamic range. Fashion photographers shooting editorial and advertising campaigns rely on IIQ to capture every texture, fabric detail, and skin tone with precision that enables extensive retouching and large-format printing. Product photographers for luxury brands, automotive manufacturers, and industrial catalogs use IIQ files to produce images that can be enlarged to billboard size without quality loss. Fine art reproduction photographers at museums and galleries worldwide use Phase One systems with IIQ output to digitize paintings, sculptures, and artifacts at resolutions that reveal brushstrokes and material textures invisible to the naked eye. Architectural and interior photographers use IIQ's exceptional dynamic range to capture both bright windows and shadowed interiors in single exposures. Aerial and landscape photographers working with Phase One's camera systems produce IIQ files for large-format prints and gallery exhibitions. Converting IIQ to widely supported formats like TIFF, JPG, or PNG is essential for client delivery, web publishing, and archival purposes, as IIQ is a specialized format primarily supported by Capture One and a limited number of other professional RAW processors.

Advantages and Disadvantages