Video Camera Technologies Systematization 2 Yasuo Takemura Abstract The video camera is a color television camera for consumer use that makes it possible for anyone to take, record and save a moving picture. This paper surveys developments in consumer video camera technology. Video cameras have been developed and manufactured in Japan for several decades and exported to global markets. Many kinds of video camera technologies developed in Japan have been applied to digital still cameras, mobile phones for communication, and even smartphones and tablets. Although compact in size, the video camera system includes a myriad of basic technologies covering a wide range of technical fields, including optical systems and lenses, image sensors – the key device in photoelectric conversion, digital signal processing for reproducing high-quality, highly-functional images, recording systems for recording images and high density mounting to bring it all together in a compact form. Furthermore, the video camera must also be small, lightweight, durable and energy-efficient, as well as the basic consumer requirements of low pricing and high reliability. The image sensor industry has developed into one of Japan’s most successful industries, supported by the timely and rapid advancement of semiconductor technology and accompanied by a wealth of specialized research. Japanese consumers expect high fidelity image quality, which has driven the development of high-quality television and video camera technologies through collaboration between sensor technology engineers and camera technology engineers, resulting in world-class quality video camera technology. Many successful image sensor technologies have been developed by Japanese engineers, such as pinned photodiodes that significantly reduce noise levels, FIT-CCD image sensors that resolve the problem of image smear, on-chip micro-lenses that enable significantly better light utilization efficiency, VOD technology to rectify issues of image blooming, interlaced addition readout, residual charge sweep-out drive technology, color-difference line-sequential systems for increasing photographic sensitivity suitable for interlaced scanning to deliver enhanced resolution. These have all been combined to produce world-class video cameras. Japan has brought out a succession of world firsts in video camera products. The world’s first single-tube video camera for consumer use, the IK-12, was commercialized in 1974 by Toshiba. This was followed by the development and commercialization of various tube-type video cameras. In 1980, Hitachi hit the markets with the world’s first solid-state, single-chip MOS image sensor video camera, the VK-C1000. In 1982, the world’s first CCD video camera, the TC-100, was commercialized by NEC, with heated competition ensuing over development and commercialization. In 1983, Sony released the BMC-100, a video camera with an integrated Betamax VCRfor recording. Later, in 1985, two types of small-scaleVCR systems were developed for integrating with video cameras, the VHS-C and 8mm. The Japan Victor Company (JVC) commercialized a VHS-C video camera, while Sony did the same with an 8mm video camera, the CCD-V8. Sony’s passport-sized compact video camera, the CCD-TR55, hit the markets in 1989 and the video camera industry truly began to take hold of the market. The competition over increasing pixel numbers was brought to a close by Toshiba unveiling its AI-XS1 high-resolution 420,000-pixel video camera. Highly functional and increasingly user-friendly video cameras then began hitting the market. Developments in video camera technology came to be widely used in surveillance, industry, medicine and other fields, producing ripple effects whereby Japanese manufacturers began unveiling a slew of world-first products, such as the color TV telephone in 1970, the electronic endoscope in 1983 (while the United States produced the world-first, Japan currently produces 70% of all electronic endoscopes), a thumb-sized camera in 1981 and a stereoscopic video camera in 1989. The reason that Japanese video camera technologies came to dominate world markets is largely due to cooperation among Japanese engineers, who exhibited a strong desire to develop new technologies in the midst of a fiercely competitive environment. In the early stages of CCD development, the technology fell short compared to the then mainstream high-end camera tubes, a situation that vexed engineers specializing in the technology, not to mention the companies they worked for. They dreamed of future success. A strong sense that they shared a common objective led engineers from competing companies to raise concerns at academic conferences, which in turn prompted sound advice from willing mentors. Image sensor and camera engineers joined forces to propose and resolve issues, gathering together the best people and nurturing talented engineers. Eventually, patent filings and successive presentations of technological achievements at gatherings of professional associations such as the IEEE and worldwide academic conferences resulted in Japan gaining global recognition for its unparalleled technological excellence. Research and development in this field appears to have turned a new corner in the 2000s. The advancement of digital technology and software ushered in a new direction. Scientific associations turned their attention to new technology, such as super-resolution technology using a mathematical approach to improve the resolution of captured images and computer imaging technology to reproduce images by capturing and converting light fields. In response to environmental changes, Japanese engineers are again laying the groundwork for new technologies to blossom. Japanese engineers excel at using new methods to create high-quality images. From here on in, there are high expectations regarding the boundless possibilities for advances in camera technology. The world is watching for new technological innovations from Japan that will bring new camera products to fruition. Video Camera Technologies Systematization 1 Contents Abstract ........................................................................ 1 6.6 Increasing Pixel Numbers ................................. 50 1. Preface ...................................................................... 3 6.7 Video Camera Trends ....................................... 50 1.1 Imaging Technology ........................................... 4 6.8 Video Camera Progress .................................... 56 1.2 Video Camera Technologies ............................... 5 6.9 Application of Video Camera Technology ........ 56 2. Optical Apparatuses .................................................. 9 7. Recording Equipment for Video Camera ................ 60 2.1 Imaging Lens ...................................................... 9 7.1 Overview .......................................................... 60 2.2 Dichroic Prism .................................................. 10 7.2 VCR.................................................................. 60 2.3 CFA (Color Filter Array) ................................... 10 7.3 Digital Recording Media .................................. 60 2.4 Optical LPF (Low Pass Filter) .......................... 10 7.4 Video Cameras using Digital Recording Media 61 2.5 Micro-Lens ....................................................... 11 8. High Function Technology ..................................... 62 2.6 Other Optical Components ............................... 11 8.1 Overview .......................................................... 62 3. Imaging Devices ..................................................... 14 8.2 AE .................................................................... 62 3.1 History of Imaging Devices (1) .......................... 14 8.3 AF ..................................................................... 62 3.2 Image Pickup Tube ........................................... 15 8.4 AWB ................................................................. 64 3.3 CCD .................................................................. 17 8.5 Image Stabilization ........................................... 65 3.4 CMOS Image Sensor ........................................ 20 8.6 Face Detection and Recognition ....................... 66 3.5 Comparison of CMOS Image Sensor and CCD 21 9. High Image Quality Technology ............................. 71 3.6 Important Imaging Device Technologies .......... 22 9.1 Contrast Correction .......................................... 71 4. Color Imaging Systems - Part 1 Image Pickup Tube 9.2 Dynamic Range Expansion .............................. 72 Era ........................................................................... 33 9.3 Demosaicing ..................................................... 73 4.1 Overview .......................................................... 33 9.4 Super-Resolution Technology ........................... 76 4.2 Single-Tube Method ......................................... 33 10. Video Camera Technology Systematization .................. 83 5. Color Television Pickup System - Part 2 CCD/CMOS 10.1 General Technology of Video Cameras ........... 83 Imager Era .............................................................. 41 10.2 Expansion of Video Camera Technology ......... 83 5.1 Bayer Method ................................................... 41 10.3 Progress of Video Camera Technology ............. 84 5.2 Color-Difference Line-Sequential Method ....... 42 10.4 Role and Contribution