• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3056-3068
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• 1996

This papre presents the RDM algorithm for composition of bit. After this, we propose a digital signature scheme for facsimile document using RDM algorithm. We modify the even-odd feature in distance of changing pel between coding line and multiple reference line which have been scanned before, and run-length in coding line. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and tensfers it, and the receiver makes a check of any forgery on the signature and the document. This scheme is compatible with the ITU-T.4(G3 or G4 facsimile standard). The total amount of data transmitted and the quality of image are about the same to that of the original document, thus a third party does not notics signature embeded on the document.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6A
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• pp.575-583
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• 2002

JBIG2 is an International Standard fur compression of Bi-level images and documents. JBIG2 supports three encoding modes for high compression according to region features of documents. One of which is generic region coding for bitmap coding. The basic bitmap coder is either MMR or arithmetic coding. Pattern matching coding method is used for text region, and halftone pattern coding is used for halftone region. In this paper, a document is segmented into line-art, halftone and text region for JBIG2 encoding and JBIG2 CODEC is implemented. For efficient region segmentation of documents, region segmentation method using wavelet coefficient is applied with existing boundary extraction technique. In case of facsimile test image(IEEE-167a), there is improvement in compression ratio of about 2% and enhancement of subjective quality. Also, we propose arbitrary shape halftone region coding, which improves subjective quality in talc neighboring text of halftone region.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.7 no.2
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• pp.55-72
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• 1997

This paper presents a digital signature scheme for facsimile document which directly embeds a signature onto the document. We use multiple reference lines which have been scanned just before and modify each distance of changing pels both on the reference line specified by key and on the coding line with a single bit of the signature data. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and transfers it, and the receiver makes a check of any forgery on the signature and the document. This scheme is compatible with the ITU-T.4(CCITT G3 or G4 facsimile standards). The total amount of data transmitted and the image quality are about the same to that of the original document, and thus a third party notices that no signature is embedded on the document.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.2
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• pp.45-59
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• 1998

Halftonig is a technique to create the appearance of intermideate tone levels by controlling the spatial distribution of the binary pixel values. Recently, many printing devices such as image setter, inkjet printer, laser printer and facsimile, generate image, they require the technique. Ordered dither is achieved comparing the gray scale image to periodic array. This method is fast, but it occurs periodic patterns. Conentional error diffusion generates a good image. But processing speed is very slow and appeares worm artifacts in middle tone scale. To improve it, Bns(Blue noise Screen) is developed based on Gaussian distribution. In this paper, we discribe methods to design BNS based human visual characteristics and to improve blue appearing at edge area of image by USM(using unsharp mask).

• The Journal of Information Technology
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• v.4 no.4
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• pp.25-35
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• 2001

This paper presents a digital signature scheme for document image which directly embeds a signature onto the document. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and transfers it and the receiver makes a check of any forgery on the signature and the document, This scheme is compatible with the ITU-T.4(CCITT G3 or G4 facsimile standards).

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.58-63
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• 1992

The discrete cosine transform (DCT)-based progressive coding standard proposed by the International Standardization Orgnnization (ISO) Joint Photographic Experts Groups (JPEG) is investigated for medical image compression and the performance of the JPEG is compared to that of the full-frame bit-allocation (FFBA) technique. From the comparison, the JPEG standard appeals superior to the FFBA technique in the following aspects: 1) JPEG achieves higher compression than the FFBA technique with less mean square error. 2) Less Gibb's artifact is observed in the compressed images by the JPEG. 3) Computational time for the JPEG is about one-fourth or the FFBA technique. Other attractive points of the JPEG include: Implementation of the JPEG with VLSIs is commercially available in relative low price and the JPEG compression format can easily be interchangeable with other applications.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.516-519
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• 2009

In the printer and the facsimile communication, digital halftoning is extremely important technologies. Error diffusion method is applied easy for color image halftoning. But the problem in error diffusion method is that a quite unrelated color has been generated though it is necessary to express the area of the grayscale in the black and white when the image that there is an area of the grayscale on a part of the color image is processed. The halftoning was assumed to be a combinational optimization problem to solve this problem, and the method of using SA (Simulated Annealing) was proposed. However, new problem existed because the processing time was a great amount compared with error diffusion method. Then, we propose the new error diffusion method.

• Journal of Korea Society of Industrial Information Systems
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• v.3 no.1
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• pp.141-151
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• 1998

The importance of fax imagerestoration is constantly increasing with the widespreasd use of facsimile machines in almost every sector of modern society. Recently, Handley and Doutherty proposed a morphological method for restoration of fax images, Their method removed effectively the only salient noise in the fax images. However, it could not remove the white and pepper noise that can appear in fax images since they treated fax images as deterministic sequences rather than random fields. Furthermore, this approach suffers from computational burden since it does not use recursive restoration technique. To cope with those difficulties, in this paper, we propose a new restoration scheme for restoring fax images using Kalman fitering which provides and efficient recursive processor. The proposed restoration method is based on the wide-sense Markov random fields (WSM).In order to verify the performance of the proposed restoration method, several experiments with the CCITT Group 3 fax machine were conducted with the generated document .Experimental results revealed that our proposed restoration method was shown to be superior to Handley et.al's method for restoring fax images.

• Electronics and Telecommunications Trends
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• v.8 no.4
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• pp.157-162
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• 1993

본 연구는 아날로그 신호를 사용하는 공중교환 전화망과 접속되는 그룹 3(G3) 팩시밀리의 화상 품질을 측정하는 방법을 제시하였다. CCITT(현 ITU-TS) 표준시험 도표 No.2를 이용하여 전송된 화상에 대한 평가는 설문조사를 통해 평가되었고, 그것들은 MOS(Mean Opinion Score) 방법에 의해 계량화되었다. 설문지의 결과에 대한 상관 분석을 통해 문항을 하나의 종합 평가 문항으로 줄일 수 있음을 살펴보았다. 그리고 그 점수들의 평균들에 대한 차이를 분석함으로써 팩시밀리 화상 품질에 영향을 미치는 요인들의 유의성을 검정하였다. 유의성을 검정하는 방법들로 t 검정법과 Vander Waerden Scores 방법을 제시하였다. 그리고 검정 결과 점수 평균이 유의하지 않은 그룹들을 하나의 그룹으로 하여 그 그룹에 있어서 점수 히스토그램을 구하였다. 이 히스토그램을 하나의 정규 분포 곡선으로 근사시켜 팩시밀리 화상 품질 평가치를 살펴보았다.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.50-55
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• 1998

A thermal printing head is used for heat transcription printing of facsimile or printer. The thermal printing head has multilayered thin films and heaters lined up. Thermal analysis of thermal printing head is important for a design of thermal printing head. Since the heating charateristics of thermal printing head is dependent on the thermal conductivities of multilayerd material, this study made numerical analysis for three dimensional transient heat conduction in mutilayered films by the finite difference method and investigated the effect of various thermal conductivities of thin films. The results of this study will be used to design thermal printing head and select the materials for thermal printing head.