By Ludimila Centeno

What Is IQ Tuning?
IQ tuning, or Image Quality tuning, is the process of adjusting various settings and parameters in a camera or image processing system to optimize the quality of the final image. This can include adjusting things like exposure, white balance, sharpness, and color saturation and often involves comparing and benchmarking the image quality of a tuned device under tests with other standard consumer devices. A well-tuned image processing system can also provide better images for algorithm consumption and therefore improve the accuracy and efficiency of artificial intelligence (AI) systems, such as deep neural networks. 

Why Do You Need IQ Tuning?
One of the main goals of IQ tuning is to ensure that the final image is representative of the scene that was captured, with accurate colors and a good balance between light and dark areas. In order for an image system to accomplish this task, all the elements must be optimized to render an output that matches the system’s requirements. Identical image systems can have very different performances based on how they are tuned. The IQ tuning requirements have objective and subjective components. While objectively it is possible to set specific targets for things like white balance, it is less direct to set targets to how vibrant or warm an image is. For products such as laptops and smartphones, once their image system is implemented there are limited degrees of freedom on what can be adjusted. In most cases these adjustments are software parameters, since physical changes are virtually impossible.

One of the most important aspects of IQ tuning is sharpness. A sharp image will have clear, well-defined edges and fine details, while a soft image will appear blurry and lack definition. There are a number of factors that can affect sharpness, including the aperture, motion in the scene vs exposure time, and the quality of the lens.

Most cameras and specifically ISP allow for more advanced IQ tuning, such as adjusting the color saturation and contrast. Color saturation refers to the intensity of the colors in an image, with high saturation resulting in more vibrant, “popping” colors, while low saturation results in more muted, subdued colors. High dynamic range is a key differentiator of modern cameras in smartphones, automotive and soon laptops. High dynamic range refers to the difference in brightness between the darkest and lightest areas of an image. During the definition of the IQ tuning objectives, it is possible to prioritize some aspects to the detriment of others, taking the use case of the camera system into consideration.

Overall, IQ tuning is an important process for ensuring that the final image is of the highest quality possible. It involves adjusting a variety of settings and parameters to achieve the desired balance of light, color, and sharpness in the final image. The process can be quite complex and requires a deep understanding of the technical aspects of image capture and processing. 

What Are the Main Criteria for Image Quality Tuning?
The main criteria for image quality tuning are: 

  1. Sharpness: This refers to the clarity and definition of the image. 
  2. Exposure: This refers to the overall brightness of the image.
  3. Color Balance: This refers to the accuracy of the colors in the image.
  4. Contrast: This refers to the difference between the light and dark areas of the image.
  5. Dynamic Range: This refers to the range of brightness levels in the image.
  6. Noise: This refers to the visual artifacts or graininess in the image.
  7. Compression: This refers to the reduction of image file size through compression algorithms.

Figure 1.  

Why Should You Use Experts For Image Quality Tuning?
Not everyone can do image quality tuning because it requires a deep level of technical expertise and knowledge of image processing techniques. Objective IQ tuning refers to a baseline of optimizations that will assure good image quality from a device. On the other hand, subjective IQ tuning is relative to a particular set of parameters that better reflects the image characteristics a certain product should have. The subjective aspect is where a manufacturer gives “its touch” to a product. That is why products with identical built in camera systems may output very different images. Although subjective IQ tuning is a big part of the overall process, not everything can be analyzed in a subjective manner, therefore, a professional IQ tuning service normally follows some standard parameters, that establish an initial baseline to objectively assessing the image quality of a device. 

To do image quality tuning well, one needs to have a solid understanding of the above criteria, and an expertise in optical design, as well as knowledge of software tools and techniques that allow you to fine-tune the image to the desired outcome and bring out the best in it. It can include adjusting several criteria, adding various effects like vignette, grain, etc. and even removing unwanted elements from the image. It requires the ability to experiment with different settings and techniques to achieve the desired result. It also requires an understanding of color theory and the ability to adjust colors to match specific needs, not to mention a massive dataset of images to experiment with.

One of the key challenges in IQ tuning is finding the optimal set of parameters for a given task. This can be a time-consuming and computationally expensive process, as it often involves training and testing models multiple times with different parameter settings. Additionally, the optimal parameters for a given task may change as the data or the task itself evolves over time, requiring ongoing tuning and maintenance. And not all these tasks can be easily automated, therefore, human expertise is required.

Another layer of complexity is that IQ tuning is not necessarily aimed to please human eyes: the vision task may be performed by ML and CV applications and these have their specific set of requirements to assure the best performance. Tuning a vision system for ML and CV requires an additional layer of expertise that is not easy to find.

Figure 2

In conclusion, IQ tuning is a crucial step in ensuring that the final image is of the highest quality and accurately represents the scene captured. It requires extensive knowledge of the technical aspects of image capture and image processing, allied to deep understanding of optics and modern imaging algorithms (HDR, Bokeh, distortion correction, etc.) to achieve the next level of smart tuning. IQ tuning requires a significant investment of time and resources, which is why the industry trend of late has been to outsource this important task to industry experts, making it more efficient and less time-consuming. 

About Ludimila Centeno
Ludimila Centeno has over 15 years of experience in Telecommunications industry in the segments of wireless communications and semiconductor industry. Having contributed to Presales, Customer Support and Operations, she has joined Immervision as Associate Vice President, Technology Offer & Support. She holds a Masters degree in Electrical Engineering where she developed research in the areas of Cognitive Radio and spectrum sensing techniques.