High-visibility focus-aid signal for ultra-high-definition television cameras using maximum value filter with sparse noise reduction

The demand for ultra-high-definition television (UHDTV) content is increasing rapidly every year owing to the prevalence of 4K TV sets and the launch of 4K/8K broadcasting services. In UHDTV content production, the difficulty of focusing high-resolution cameras has become one of the most critical issues. We previously proposed a focus-aid signal for use in 8K UHDTV cameras, which facilitated precise focusing using a low-resolution viewfinder. However, the signal visibility degraded when an image included sparse noise. In this paper, we describe an effective sparse noise reduction technique based on an improved maximum value filter in the focus-aid signal generation circuit. The improved focus-aid signal technique has also been applied in focus-assistance units in 4K cameras and UHDTV content production.

I. Introduction

THE demand for ultra-high-definition television [1] (UHDTV) content is rapidly increasing each year owing to the prevalence of 4K TV sets and the launch of 4K/8K broadcast services, including satellite broadcasting, terrestrial broadcasting, and Internet video streaming [2]–[4]. With the increasing amount of UHDTV content, the difficulty of focusing UHDTV cameras has become one of the most critical issues in the field of television production. This focusing difficulty results from the higher and shallower resolution and depth of field in UHDTV cameras than those of conventional high-definition television (HDTV) cameras.