Challenges and system considerations in 8K imaging

The transition to an 8K imaging system involves far more challenges than simply increasing the number of pixels. 8K typically means a horizontal resolution of around 7680 pixels at up to 60 frames per second, which generates a huge amount of data that pushes the entire system to its limits. In addition to the sensor, every element of the image chain plays a crucial role: optics, interfaces, image signal processor (ISP), and encoding must be perfectly coordinated to meet the high demands on performance and image quality. In practice, an 8K system is not a simple scaling of 4K, but a complex interplay of various factors that must all be balanced with each other.

Data rate and processing complexity

Since the number of pixels increases by a factor of four from 4K to 8K, the amount of data that must be processed per unit of time also quadruples. Typical sensors in the 8K range reach over 30 to 60 megapixels, generating huge amounts of data that must be captured and processed within a few milliseconds. Conventional MIPI D-PHY interfaces, such as the widely used D-PHY version 1.2 with 2.5 Gbit/s per lane, reach their limits here. Although there are more modern specifications (e.g., D-PHY 2.1 with 4.5 Gbit/s per lane), even these have high transmission rate requirements, meaning that only around 30 to 35 frames per second are realistic at 8K. For system specialists, this means that not only the recording, but also the data transfer and processing must be powerful and synchronized in order to prevent delays or data loss.

Sensor size, pixel density, and dynamic range

The size of the sensor directly influences the image quality and the cost of the system. Large sensors with a diagonal length of over 40 mm, such as the Sony IMX455 with 61 megapixels, deliver high light sensitivity, wide dynamic range, and low noise due to their large pixels. However, they require expensive optics and are mostly found in professional DSLR cameras. Small sensors with a diagonale of less than one inch (25 mm) use small pixels of approximately. 0.8 µm, which allows for compact designs but limits their light sensitivity and color saturation. Special color filter arrays such as Quad Bayer or Quad Color Filter Arrays are necessary for such sensors, which requires significantly more complex image signal processing to avoid color casts and artifacts. These compromises therefore affect both the physical properties of the sensor and the requirements for downstream image processing.

Optical requirements

High resolutions and small pixels place very high demands on the optics. The lens must have a very high modulation transfer function (MTF) so that the fine details of the sensor pixels can actually be captured and imaged. The size of the diffraction disk is crucial, especially for pixel sizes below 1 µm, where an f-stop smaller than 1 is often used as a guideline to keep the circle of confusion small enough. In addition, sensors with small pixels often require shorter focal lengths to ensure the same image angle, which leads to fisheye distortion, which in turn must be compensated for by complex image correction algorithms. Furthermore, the chief ray angle (CRA) of the sensor is not insignificant: Sensors with a large CRA require special, customized lenses to avoid edge shading and crosstalk. These are often challenges that are not trivial to solve in the system design of 8K cameras.

ISP tuning and artifact management

Complex filter arrays and multi-pixel technologies such as Quad Bayer pose significant challenges when it comes to remosaicing, i.e., converting the multi-pixel structure into a standard RGB image. Classic demosaicing algorithms are often insufficient, as the risk of color artifacts, aliasing, and ghosting is high. To achieve a clean, artifact-free image, deep tuning is required, in which hardware-related adjustments on the sensor are closely integrated with the ISP algorithms. This intensive fine-tuning ensures that color reproduction is improved and noise and false color characteristics are significantly reduced. This achieves the demanding image quality required for professional 8K systems.

Practical system examples at FRAMOS

FRAMOS has demonstrated this with concrete prototypes using Sony IMX586 sensors, combining sensor board design with wire bonding, special optics, and high-speed interfaces to NVIDIA Jetson platforms. Intensive tuning and testing processes eliminated color errors and significantly optimized image display, resulting in a higher level of detail and improved contrast compared to 4K systems. Such pre-validated systems and development kits enable customers to implement their own 8K projects faster and more reliably, significantly reducing development costs and the time to market.

Building an 8K vision system is a multidisciplinary challenge, with sensor resolution being just one aspect. Data rate management, optical precision, ISP tuning, and interface requirements must be considered and optimized holistically to ensure high image quality and performance. FRAMOS supports customers with pre-validated solution kits and customized engineering support along the way.