Imaging system having White-RGB color filter array

Getman, A. I.; Kim, Jin-Hak; Kim, Tae-Chan

doi:10.1109/icip.2010.5652731

Cited by 16 publications

(15 citation statements)

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“…The training method predefines logical functions for estimating missing red, green, and blue channels at white locations [5]. By comparing the resulting values from the predefined functions with the resulting measured values from a real device, the pixel values of the missing red, green, and blue can be estimated.…”

Section: Related Workmentioning

confidence: 99%

“…This method is ineffective when edges occur near white target pixels; therefore, an edge-adaptive method was proposed for avoiding blur defects near target white pixels [4]. The edge-adaptive color separation method interpolates three channels at white target locations if edges are not detected; The training method predefines logical functions for estimating missing red, green, and blue channels at white locations [5]. By comparing the resulting values from the predefined functions with the resulting measured values from a real device, the pixel values of the missing red, green, and blue can be estimated.…”

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confidence: 99%

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Demosaicing Method for Digital Cameras with White-RGB Color Filter Array

Park¹,

Jang²,

Chong³

2016

ETRI J

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Demosaicing, or color filter array (CFA) interpolation, estimates missing color channels of raw mosaiced images from a CFA to reproduce full-color images. It is an essential process for single-sensor digital cameras with CFAs. In this paper, a new demosaicing method for digital cameras with Bayer-like W-RGB CFAs is proposed. To preserve the edge structure when reproducing full-color images, we propose an edge direction-adaptive method using color difference estimation between different channels, which can be applied to practical digital camera use. To evaluate the performance of the proposed method in terms of CPSNR, FSIM, and S-CIELAB color distance measures, we perform simulations on sets of mosaiced images captured by an actual prototype digital camera with a Bayer-like W-RGB CFA. The simulation results show that the proposed method demosaics better than a conventional one by approximately +22.4% CPSNR, +0.9% FSIM, and +36.7% S-CIELAB distance.Keywords: Bayer-like White-RGB, color filter array interpolation, demosaicing, digital camera, W-RGB color filter array. Manuscript received Nov. 27, 2014; revised Oct. 5, 2015; accepted Oct. 14, 2015. SK hynix provided the research facilities for this study. Jongjoo Park (herojongjoo@gmail.com) and Jong-Wha Chong (corresponding author; jchong@hanyang.ac.kr) are with the Department of Electronics Engineering, Hanyang University, Seoul, Rep. of Korea.Euee Seon Jang (esjang@hanyang.ac.kr) is with the Division of Computer Science & Engineering, Hanyang University, Seoul, Rep. of Korea. I. IntroductionWhile the resolutions of digital cameras continue to increase, the size of complementary metal-oxide-semiconductor (CMOS) image sensors remains limited. As a result, CMOS image sensors now contain a very large number of pixels; however, the sizes of sensor elements within a color filter array (CFA) [1] are becoming increasingly smaller, and the amount of light absorbed in a given period by each element is therefore significantly decreased. This degradation of light sensitivity can lead to deterioration in image quality -something that is particularly evident in images shot in low-light conditions.Images captured in low-light conditions by a digital camera that uses a CMOS sensor can be affected by significant blurring and noise because a long exposure time is required for the aperture to gather enough light to produce acceptable images. To overcome this defect, a sensor with a higher sensitivity is required. To address this need, a White-RGB (W-RGB) CFA, which has greater sensitivity than a conventional Bayer CFA, was developed [2]. Fig. 1. Figures 1(a) and 1(b) are examples of a conventional Bayer CFA pattern and a Bayer-like W-RGB CFA pattern, respectively. A Bayerlike W-RGB CFA substitutes one green filter array in every 2 × 2 matrix of a Bayer CFA with a white filter array (W 2x,x ), which is made from transparent resin films. These white filter arrays can be penetrated by all visible light with wavelengths of 450 nm to 700 nm. In other words, the white filter arrays in...

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Section: Related Workmentioning

confidence: 99%

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confidence: 99%

Demosaicing Method for Digital Cameras with White-RGB Color Filter Array

Park¹,

Jang²,

Chong³

2016

ETRI J

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“…1 (a)) provides information on the intensity of [5], (b) Red, Green, Blue, and Emerald (RGBE) CFA, (c) Cyan, Yellow and Magenta (CYYM) CFA, (d) the Bayer-like 2-by2 White, Red, Green, and Blue (WRGB) CFA [6]- [8] discussed in this paper, (e) Kodak 2.0 4-by-4 WRGB CFA [9], (f) Sony 4-by-4 WRGB CFA [10]. Manuscript light in the red, green, and blue (RGB) wavelength regions.…”

Section: Introductionmentioning

confidence: 99%

“…In order to achieve a high transmission ratio in visible spectrum, White-RGB (WRGB) imaging systems [6]- [8] replace one of the green pixels of the Bayer CFA with a "white pixel" (Fig. 1 (d)).…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the color reproduction performance of two of these systems [6], [7], is not ideal since the average based color separation method is not robust. Another training approach has been proposed to address the color issue in the third system [8], however it is not suitable for implementation in cell phone due to its high complexity.…”

Section: Introductionmentioning

confidence: 99%

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An Improved White-RGB Color Filter Array Based CMOS Imaging System for Cell Phones in Low-Light Environments

Wang

Chong

2014

IEICE Trans. Inf. & Syst.

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SUMMARYIn this paper, a novel White-RGB (WRGB) color filter array-based imaging system for cell phone is presented to reduce noise and reproduce color in low illumination. The core process is based on adaptive diagonal color separation to recover color components from a white signal using diagonal reference blocks and location-based color ratio estimation in the luminance space. The experiments, which are compared with the RGB and state-of-the-art WRGB approaches, show that our imaging system performs well for various spatial frequency images and color restoration in low-light environments.

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