KEYWORDS: Signal processing, Camera shutters, Video, Cameras, Modulation transfer functions, Light sources, Imaging systems, Image sensors, Light, Signal generators
This study proposes a flicker reduction method for 120 fps shooting under 100 Hz light fluctuation. In 120 fps videos, a 100 Hz light fluctuation causes a 20 Hz flicker, which is an aliasing artifact induced by its sampling frequency. In this method, the frame period of 1/120 s is divided into 1/150 s and 1/600 s exposure by using a double rolling shutter. Each pixel alternatively outputs 1/150 s and 1/600 s exposure signals which are readout by a readout circuit operated at double the rate of a normal 120 fps operation. A 120 fps signal with an exposure time of 1/100 s is obtained by summing three consecutive signals with exposures of 1/600, 1/150, and 1/600 s. This method is effective for flicker reduction even in the presence of several light sources with different amplitudes and phases. We implemented this method to an 8K camera and examined the flicker reduction effect for an 8K 120 fps video. As a result, the 20 Hz flicker was suppressed to less than one-tenth.
KEYWORDS: Modulation, Projection systems, High dynamic range imaging, RGB color model, Image resolution, Signal processing, Modulation transfer functions, Video, Relays, LCDs
We are currently researching a next-generation broadcasting system named "Super Hi-Vision", which provides images
with much higher resolution and quality than a high definition television, and are developing displays for this system. We
have developed a projector which can display the high-resolution images of Super Hi-Vision (7680x4320 pixels) and has
a high dynamic range of 1.1 million to 1. This projector features a serial combination of two modulation blocks: the first
block for chrominance modulation and the second block for luminance modulation. While a conventional projector has one
modulation block that contains three devices to modulate red, green, and blue light, our projector has another modulation
block that contains a device for luminance to further modulate the combined RGB modulated light. This configuration
enables the projector to output high-resolution color images by combining three low-resolution devices for chrominance
modulation and one high-resolution device for luminance modulation. As a high-resolution device, we have newly developed
a 1.75-inch liquid crystal on silicon device with 8192x4320 pixels. In addition, the dynamic range is dramatically
improved because this dual modulation scheme minimizes the black levels in projected images. We demonstrated that our
projector displays Super Hi-Vision color images and that it has an extremely high dynamic range of 1.1 million to 1 and a
fine 10-bit tone reproduction.
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