Color Difference Components Research Articles

Development of a novel colorimetric food package label for monitoring lean pork freshness

The aim of this work was to develop an easy-to-use food package label for pork shelf-life assessment. Meat samples were packaged in polyethylene terephthalate trays with on-package indicator labels and kept at 5 °C for 8 days. These indicators contained three groups of pH-sensitive dyes, i.e., bromocresol purple, bromothymol blue, and a mixture of bromothymol blue and methyl red. Results of pH, total volatile basic nitrogen (TVB-N) contents, aerobic plate counts and sensory scores of pork differentiated between fresh (on 0–3 days), medium fresh (on 4–5 days), and spoiled lean pork (on 6–8 days). Results of total color difference and principal components analysis carried out with colorimetric data of different indicator labels showed that the indicator label made by a mixture of bromothymol blue and methyl red at 3:2 proportion (at an initial pH of 5.0) was able to discriminate fresh (red), medium fresh (goldenrod), and spoiled (green) pork in cold storage. The statistical models obtained by partial least squares, with the color change of label, successfully predicted TVB-N contents and aerobic plate counts of pork. These results suggest the potential feasibility of this particular indicator system for monitoring freshness of packaged pork via color change detected directly using the naked eye.

쿼드트리 분할 기술을 이용한 컬러 영상 암호화 기술

최근 다양한 형태의 영상 콘텐츠가 제작되고 있고, 이를 위한 저작권 보호기술에 대한 관심이 높아지고 있다. 본 논문에서는 컬러 영상을 위한 영상암호화 기술을 제안한다. 이 기술은 영상을 RGB 색차성분으로 분할한 후, 윤곽선을 기준으로 쿼드트리 분할을 수행한다. 쿼드트리 분할 후, 선정된 블록들을 대상으로 암호화를 수행한다. 색차성분을 대상으로 암호화를 수행하여 암호화 효율을 측정하고, 컬러 영상으로 재구성한 후에도 암호화 효율을 측정한다. 암호화 효율은 시각적인 측정방식과 객관적인 화질평가 방식을 이용한다. 실험결과 PSNR 수치는 색차성분의 경우 7~10[dB], 컬러 영상의 경우 16~19[dB]로 측정되었다. 본 논문에서 제안한 영상암호화 기술은 향후 다양한 디지털 영상 콘텐츠의 저작권 보호에 사용될 것으로 보인다. Recently, various types of image contents are being produced, and interest in copyright protection technology is increasing. In this paper, we propose an image encryption technology for color images. This technique divides the image into RGB color components and then performs quad-tree decomposition based on the edge of image. After the quad-tree partitioning, encryption is performed on the selected blocks. Encryption is performed on color components to measure encryption efficiency, and encryption efficiency is measured even after reconstitution into a color image. The encryption efficiency uses a visual measurement method and an objective image quality evaluation method. The PSNR values were measured as 7~10 dB for color difference components and 16~19 dB for color images. The proposed image encryption technology will be used to protect copyright of various digital image contents in the future.

A New Wide-Gamut RGB Primary Set and Efficient Color Encoding Methods for Ultrahigh-Definition Television (UHDTV)

This paper introduces a new wide-gamut RGB primary set and a new color-encoding method that are developed for ultrahigh-definition television (UHDTV). The extended gamut RGB-primary set compared with the conventional CRT-centric gamut is proposed in favor of inclusion of real-world surface colors and in consideration of the current and prospective colorimetric characteristics of flat panel displays using which UHDTV programs will likely be reproduced. The new color encoding method is derived to enable luminance and chrominance information to be accurately separated, resulting in orthogonal video signals. The new luma and color-difference signals generated by the newly derived encoding scheme are demonstrated to have insignificant crosstalk. It is also shown that this fact can contribute to improving image quality after subsampling color-difference components and to increasing compression efficiency.

Chrominance signal interpolation of YUV 4:2:0 format color images

AbstractThe YUV 4:2:0 format is a representative format for color images in international standards. In this format, both color difference components U and V reduce the number of pixels in the horizontal and vertical directions by one‐half. Consequently, this reduction degrades the color difference components. At a relatively high bit rate, the degradation produced by reducing the number of pixels is often worse than the degradation that depends on the coding. Thus, processing to compensate for the degradation due to the format transform becomes necessary. The pixels of the color difference components reduced once on the encoding side are determined by interpolation on the decoding side. The typical interpolation methods are bilinear interpolation, bicubic interpolation, and interpolation by a finite impulse response (FIR) filter. When these interpolation methods were applied to interpolate the color difference components in the YUV 4:2:0 format, blur and lower saturation were produced in the colors in the color difference components returned to the original number of pixels. In this paper, we propose a method that uses information in the luminance component not having a reduced number of pixels to interpolate the color difference components in the YUV 4:2:0 format. Consequently, color blurring is prevented in the edges of the image, and an objective is to improve the saturation in the entire image. We based the proposed method on bilinear interpolation and bicubic interpolation, and formulated an interpolation method using the luminance component as an extended form. The proposed method and the bicubic interpolation are compared in both objective and subjective evaluations, and demonstrate the effectiveness of the proposed method. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 89(9): 1–10, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20218

Color image denoising using wavelets and minimum cut analysis

Wavelet thresholding has proven to be an efficient edge-preserving denoising method for grayscale images, especially when it exploits the interscale correlations of wavelet coefficients. Intrascale correlations can further improve the denoising performance, but the gain for grayscale images is generally small. In this letter, we demonstrate that the gain can become substantial in color image denoising, especially for smooth image color-difference components. We then propose a new denoising method, based on the minimum cut algorithm, to exploit both the interscale and intrascale correlations of wavelet coefficients. The proposed method achieves up to 5-dB gain in peak signal-to-noise ratio for color-difference images and leads to fewer visual color artifacts.

Polyphase FIR filters for the demodulation of chrominance signals

The author presents an estimation scheme and its polyphase finite-duration impulse-response (FIR) filter implementation for the demodulation of composite chrominance signals into color difference components such as in-phase and quadrature-phase components. A decoding scheme with three-tap polyphase FIR filters is presented. The least square error estimators, which estimate the chrominance components, are derived and their performance analyzed. The composite video signal is reviewed and the digitization of the video signal is described. The author formulates the demodulation of the digitized video signal as an estimation problem. A polyphase FIR filter implementation of the resultant estimators for the chrominance components is then described. >

The EBU C-MAC/Packet System for Direct Broadcasting by Satellite

After three years of research and development work conducted by an international team, the EBU has recommended the adoption of a system termed C-MAC/packet, for direct satellite broadcasting using 625-line television standards. This system is based on the generalized use of time-division multiplexing, the sequential transmission of time-compressed luminance and color-difference components, and the principle of packet multiplexing for sound and data broadcasting services. This system will permit an appreciable improvement to be made in the quality of the picture and sound, together with an increased quantity and diversity of services offered to the public. This article explains the technical principles of the system.

DPCM Quantization of Color Television Signals

The application of DPCM to the coding of color television signals calls for the design of the quantization characteristics for the luminance and the two color difference components. In this paper we describe quantizer designs based on visibility thresholds of quantization noise measured as a function of prediction error for a number of test slides. We assume a quantizer for the luminance component designed previously by a similar procedure and conduct psychovisual tests for the U and V color components. The results show that, mainly for granular noise, there is some visual superposition of quantization noise between the luminance and the U chrominance signals, while little or no visual interaction is evident between the luminance and the V signal impairments. The quantizers for the U and V components are designed such that, with the previously designed luminance quantizer, the number of levels are minimized without exceeding the visibility thresholds. We conclude that a total of 6 bits per color sample are required to code the U and V components together at 4.4 MHz.