Technologies to Improve Image Information Quality
Light intensity is the most important information and contains both sensitivity and dynamic range (DR). This chapter discusses the DR, which is the range of light intensity information that a sensor can capture. Sensors measure the amount of light coming to each built-in coordinate point, and sensitivity is important to their performance. The most direct method to enhance the Nyquist frequency is to increase the pixel number. The development of technologies that make effective use of photons and signal charges, such as on-chip lens proposed in the early 1980s, antireflection film, backside illumination, and advanced front-side illumination. All the sensors described thus far have continuous output with continuous capturing. In contrast, in a burst-type sensor, on-chip frame memories are equipped to store captured image signal charges for giving priority to higher frame rate by avoiding output operation at each frame, which needs driving and output time.