Effect of Illumination in Chroma Key Effect in the Realization of Virtual Television Studio (original) (raw)

A New Calibration Process for a Homogeneous Cyclorama Illumination in Virtual TV Sets

Applied Sciences

A virtual TV set combines actors and objects with computer-generated virtual environments in real time. Nowadays, this technology is widely used in television broadcasts and cinema productions. A virtual TV set consists of three main elements: the stage, the computer-system and the chroma-keyer. The stage is composed by a monochrome cyclorama (the background) in front of which actors and objects are located (the foreground). The computer-system generates the virtual elements that will form the virtual environment. The chroma-keyer combines the elements in the foreground with the computer-generated environments by erasing the monochrome background and insetting the synthetic elements using the chroma-keying technique. In order to ease the background removal, the cyclorama illumination must be diffuse and homogeneous, avoiding the hue differences that are introduced by shadows, shines and over-lighted areas. The analysis of this illumination is usually performed manually by an expert ...

Chroma Keying in an Immersive Virtual Environment

1999

This paper presents a very fast software chroma keying algorithm, requiring at most five integer operations per pixel. An improvement of more than 300% in performance over HLS based algorithms was achieved. The algorithm has been developed for use in an immersive virtual environment, which is also described here.

Software Chroma Keying in an Immersive Virtual Environment

South African Computer Journal, 1999

FPGA implementation for real-time Chroma-key effect using Coarse and Fine Filter

2013 International Conference on Computing, Management and Telecommunications (ComManTel), 2013

Chroma-key is a robust and important technique for processing image or video that is widely used in cinema films, magazine covers, video game industries as well as television programs such as weather forecast, live talk show, ect. This paper presents study of Chroma-key method and proposes a hardware architecture for Chroma-key effect in real-time. Based on K-means algorithm, we propose an improved method namely Coarse and Fine Filter, which is more robust on segmentation and more appropriate for hardware design thanks to usage of small buffer. A VLSI architecture for the proposed method is implemented on the Altera DE2 FPGA board. Experimental results show that the proposed design can perform Chroma-key effect with pleasing quality in real-time.

Digital illumination for augmented studios

Journal of Virtual Reality …, 2006

Virtual studio technology plays an important role for modern television productions. Blue-screen matting is a common technique for integrating real actors or moderators into computer generated sceneries. Augmented reality offers the possibility to mix real and virtual in a more general context. This article proposes a new technological approach for combining real studio content with computer-generated information. Digital light projection allows a controlled spatial, temporal, chrominance and luminance modulation of illumination opening new possibilities for TV studios.

Chroma Conversion Master's Project Report

For human–computer interaction, most devices use the fingers, sometimes the whole hand. And short of organ pedals, the fingers remain the primary source of triggering musical instrument digital interface (MIDI) synthesizers. This project offers an alternative in using the color intensity and hue controlled through objects manipulated or worn as clothing or ornament by the human body, as detected by a camera across the several zones of the video image. The method is explained in this report, along with pitfalls, perturbations, as well as performance and paradigm.

Lighting and display screens: Models for predicting luminance limits and disturbance

Lighting Research and Technology, 2012

An investigation of the level of disturbance caused by reflections from a variety of display screens, including interactive whiteboards, has been carried out using three test methods: Luminance adjustment, category rating and reading. The results from the luminance adjustment test and the category rating test were consistent, both showing similar significant effects of lighting-display parameters on the disturbance caused by screen reflections. In contrast, the objective measure of task performance in the reading test was barely responsive to reflections on the screens. Two models have been developed, one to predict the luminaire luminance at which 95% of observers were not disturbed by the reflections and the other to predict the rating of disturbance caused by reflections from the screens. Both models are based on lighting-display parameters including the size and luminance of the reflected light source and the specular reflectance, the effect of haze reflection and the background luminance of the display screen. These models can be used generally, to guide lighting recommendations and, specifically, to identify suitable luminaires to be used with given set of display screens or suitable display screens to be used with a given lighting installation.

Influence of chroma variations on naturalness and image quality of stereoscopic images

Human Vision and Electronic Imaging XIV, 2009

The computational view on image quality of Janssen and Blommaert states that the quality of an image is determined by the degree to which the image is both useful (discriminability) and natural (identifiability). This theory is tested by creating two manipulations. Firstly, multiplication of the chroma values of each pixel with a constant in the CIELab color space, i.e., chroma manipulation, is expected to increase only the usefulness by increasing the distances between the individual color points, enhancing the contrast. Secondly, introducing stereoscopic depth by varying the screen disparity, i.e., depth manipulation, is expected to increase both the usefulness and the naturalness. Twenty participants assessed perceived image quality, perceived naturalness and perceived depth of the manipulated versions of two natural scenes. The results revealed a small, yet significant shift between image quality and naturalness as a function of the chroma manipulation. In line with previous research, preference in quality was shifted to higher chroma values in comparison to preference in naturalness. Introducing depth enhanced the naturalness scores, however, in contrast to our expectations, not the image quality scores. It is argued that image quality is not sufficient to evaluate the full experience of 3D. Image quality appears to be only one of the attributes underlying the naturalness of stereoscopic images.

Hue-Shift Modeling and Correction Method for High Luminance Display

Journal of Imaging Science and Technology, 2008

The human eye usually experiences a loss of color sensitivity when it is subjected to high levels of luminance, and perceives a discrepancy in color between high and normal-luminance displays, generally known as a hue shift. Accordingly, this paper models the hue-shift phenomenon and proposes a hue correction method to provide perceptual matching between high and normalluminance displays. The modeling of the hue-shift phenomenon is determined by perceived hue matching experiments. To quantify the hue-shift phenomenon for the whole hue angle, 24 color patches with the same lightness are first created and equally spaced inside the hue angle for three lightness levels. These patches are then displayed one-by-one on both displays with the ratio of luminance between the two displays. Next, the hue value for each patch appearing on the high luminance display is adjusted by observers until the perceived hue for the patches on both displays appears the same visually. After obtaining the hue-shift values from the perceived hue matching experiment, these values are fit piecewise into seven sinusoidal functions to allow the shifted-hue amounts to be approximately determined for arbitrary hue values of pixels in a high luminance display and then used for correction. Essentially, the input red green blue (RGB) values of an image are converted to CIELAB values by a forward characterization model, and then, LCh (lightness, chroma, and hue) values are calculated to obtain the hue values for all the pixels. These hue values are shifted according to the amount calculated by the functions of the hue-shift model. Finally, the corrected CIELAB values are calculated from lightness, chroma, and corrected hue values, and after that, the output RGB values for all pixels are estimated by an inverse characterization model. For evaluation, an observer's preference test was performed using several test images with other hue shift results and the comparison results are shown with a z score.

Effect of Illumination in Chroma Key Effect in the Realization of Virtual Television Studio (original) (raw)

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