Digital Color Imaging

This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented us-ing vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided

Pushing the Limits of 3D Color Printing: Error Diffusion with Translucent Materials

Accurate color reproduction is important in many applications of 3D printing, from design prototypes to 3D color copies or portraits. Although full color is available via other technologies, multi-jet printers have greater potential for graphical 3D printing, in terms of reproducing complex appearance properties. However, to date these printers cannot produce full color, and doing so poses substantial technical challenges, from the shear amount of data to the translucency of the available color materials. In this paper, we propose an error diffusion halftoning approach to achieve full color with multi-jet printers, which operates on multiple isosurfaces or layers within the object. We propose a novel traversal algorithm for voxel surfaces, which allows the transfer of existing error diffusion algorithms from 2D printing. The resulting prints faithfully reproduce colors, color gradients and fine-scale details.Comment: 15 pages, 14 figures; includes supplemental figure

Navigating the roadblocks to spectral color reproduction: data-efficient multi-channel imaging and spectral color management

Commercialization of spectral imaging for color reproduction will require the identification and traversal of roadblocks to its success. Among the drawbacks associated with spectral reproduction is a tremendous increase in data capture bandwidth and processing throughput. Methods are proposed for attenuating these increases with data-efficient methods based on adaptive multi-channel visible-spectrum capture and with low-dimensional approaches to spectral color management. First, concepts of adaptive spectral capture are explored. Current spectral imaging approaches require tens of camera channels although previous research has shown that five to nine channels can be sufficient for scenes limited to pre-characterized spectra. New camera systems are proposed and evaluated that incorporate adaptive features reducing capture demands to a similar few channels with the advantage that a priori information about expected scenes is not needed at the time of system design. Second, proposals are made to address problems arising from the significant increase in dimensionality within the image processing stage of a spectral image workflow. An Interim Connection Space (ICS) is proposed as a reduced dimensionality bottleneck in the processing workflow allowing support of spectral color management. In combination these investigations into data-efficient approaches improve two critical points in the spectral reproduction workflow: capture and processing. The progress reported here should help the color reproduction community appreciate that the route to data-efficient multi-channel visible spectrum imaging is passable and can be considered for many imaging modalities

Currency security and forensics: a survey

By its definition, the word currency refers to an agreed medium for exchange, a nation’s currency is the formal medium enforced by the elected governing entity. Throughout history, issuers have faced one common threat: counterfeiting. Despite technological advancements, overcoming counterfeit production remains a distant future. Scientific determination of authenticity requires a deep understanding of the raw materials and manufacturing processes involved. This survey serves as a synthesis of the current literature to understand the technology and the mechanics involved in currency manufacture and security, whilst identifying gaps in the current literature. Ultimately, a robust currency is desire

Print engine color management using customer image content

The production of quality color prints requires that color accuracy and reproducibility be maintained to within very tight tolerances when transferred to different media. Variations in the printing process commonly produce color shifts that result in poor color reproduction. The primary function of a color management system is maintaining color quality and consistency. Currently these systems are tuned in the factory by printing a large set of test color patches, measuring them, and making necessary adjustments. This time-consuming procedure should be repeated as needed once the printer leaves the factory. In this work, a color management system that compensates for print color shifts in real-time using feedback from an in-line full-width sensor is proposed. Instead of printing test patches, this novel attempt at color management utilizes the output pixels already rendered in production pages, for a continuous printer characterization. The printed pages are scanned in-line and the results are utilized to update the process by which colorimetric image content is translated into engine specific color separations (e.g. CIELAB-\u3eCMYK). The proposed system provides a means to perform automatic printer characterization, by simply printing a set of images that cover the gamut of the printer. Moreover, all of the color conversion features currently utilized in production systems (such as Gray Component Replacement, Gamut Mapping, and Color Smoothing) can be achieved with the proposed system

AN ALGORITHM FOR RECONSTRUCTING THREE-DIMENSIONAL IMAGES FROM OVERLAPPING TWO-DIMENSIONAL INTENSITY MEASUREMENTS WITH RELAXED CAMERA POSITIONING REQUIREMENTS, WITH APPLICATION TO ADDITIVE MANUFACTURING

Cameras are everywhere for security purposes and there are often many cameras installed close to each other to cover areas of interest, such as airport passenger terminals. These systems are often designed to have overlapping fields of view to provide different aspects of the scene to review when, for example, law enforcement issues arise. However, these cameras are rarely, if ever positioned in a way that would be conducive to conventional stereo image processing. To address this, issue an algorithm was developed to rectify images measured under such conditions, and then perform stereo image reconstruction. The initial experiments described here were set up using two scientific cameras to capture overlapping images in various cameras positons. The results showed that the algorithm was accurately reconstructing the three-dimensional (3-D) surface locations of the input objects. During the research an opportunity arose to further develop and test the algorithms for the problem of monitoring the fabrication process inside a 3-D printer. The geometry of 3-D printers prevents the location of cameras in the conventional stereo imaging geometry, making the algorithms described above seem like an attractive solution to this problem. The emphasis in 3-D printing on using extremely low cost components and open source software, and the need to develop the means of comparing observed progress in the fabrication process to a model of the device being fabricated posed additional development challenges. Inside the 3-D printer the algorithm was applied using two scientific cameras to detect the errors during the printing of the low-cost open-source RepRap style 3-D printer developed by the Michigan Tech’s Open Sustainability Technology Lab. An algorithm to detect errors in the shape of a device being fabricated using only one camera was also developed. The results show that a 3-D reconstruction algorithm can be used to accurately detect the 3-D printing errors. The initial development of the algorithm was in MATLAB. The cost of the MATLAB software might prevent it from being used by open-source communities. Thus, the algorithm was ported to Python and made open-source for everyone to use and customize. To reduce the cost, the commonly used and widely available inexpensive webcams were also used instead of the expensive scientific cameras. In order to detect errors around the printed part, six webcams were used, so there were 3 pairs of webcams and each pair were 120 degrees apart. The results indicated that the algorithms are precisely detect the 3-D printing errors around the printed part in shape and size aspects. With this low-cost and open-source approach, the algorithms are ready for wide range of use and applications

The Journal of Undergraduate Research: Volume 13

This is the complete issue of the South Dakota State University Journal of Undergraduate Research, Volume 13

Digital imaging technology assessment: Digital document storage project

An ongoing technical assessment and requirements definition project is examining the potential role of digital imaging technology at NASA's STI facility. The focus is on the basic components of imaging technology in today's marketplace as well as the components anticipated in the near future. Presented is a requirement specification for a prototype project, an initial examination of current image processing at the STI facility, and an initial summary of image processing projects at other sites. Operational imaging systems incorporate scanners, optical storage, high resolution monitors, processing nodes, magnetic storage, jukeboxes, specialized boards, optical character recognition gear, pixel addressable printers, communications, and complex software processes

누설전자파를 위한 방사 보안 레벨 및 신호 복원

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2013. 8. 김성철.In this dissertation, reconstruction of electromagnetic emanation security (EMSEC)-channel information for video display units and printer are reconstructed using the averaging technique and proposed adaptive deringing filter. Also, emission security limits are proposed based on the analysis of the indoor EMSEC-channel. An emitted waveform from equipment which manages the important information can be detected and restored intentionally using the sensitive antenna and high performance receiver. These documents related to the EMSEC have classified by high confidentiality so that these are prohibited to publish by military organization. For this reason, reasonable emission security limits for various electronic devices dealing with significant information are necessary. Firstly, we try to identify the exact a signal characteristics and the frequency components to measure and analyze the spectrum of electromagnetic waves which are contained information on personal computer (PC) and printer. The target devices are the desktop, laptop and laser printer which is generally used in the domestic offices in this study. The printer processed a large amount of information for a short period of time, there may be leaked the information in this process. To verify the leakage of electromagnetic spectrum that contains information, we measure and analyze the whole spectrum from 100 MHz to 1000 MHz. Secondly, we represent how to build the EMSEC-system and to restore the signal leakage of electromagnetic waves on the basis of the signal characteristics of the electromagnetic wave leakage of printer and video display unit (VDU) of PC. The parameters that can improve the performance of signal recovery of the leakage electromagnetic wave, it can be given antenna sensitivity, resolution bandwidth (RBW) of the receiver, and signal processing gain. To adjust the signal processing gain, antenna which have the high antenna gain, and the use of wider RBW on receiver are improved hardware of EMSEC system. Whereas image restoration algorithm for EMSEC system as post-processing is a portion corresponding to the software of EMSEC system. Techniques for increasing signal strength and noise reduction are particularly important when trying to measure compromising emanations because the magnitude of these signals can be extremely small. Averaging technique find to achieve maximum cross correlation between recorded electromagnetic leaked signals. That method is a practical, highly effective and widely used technique for increasing the signal-to-noise ratio (SNR) of a periodic signal, such as that generated by the image-refresh circuitry in a video display system. But, the printer and facsimile exhibit aperiodicity in their EMSEC-channel information during their operation state unlike video display systems. Since the aperiodic EMSEC-channel information of equipments such as printers and faxes is not involved in processing gain, the differences between periodic- and aperiodic compromising emanations need to be considered in order to establish emission security limits. In addition to, we propose the adaptive deringing filter to reconstruct the EMSEC- channel information from PC and printer. We can obtain that the minimum peak signal-to-noise ratio (PSNR) enhancement is 2 and maximum PSNR enhancement is 10 compared with the original reconstructed image. Next, we perform the EMSEC-channel measurements in the 100?1000 MHz frequency bands. Second, we analyze the pathloss characteristics of the indoor EMSEC-channel based on these measurements. We find the frequency correlation pathloss characteristics of compromising emanations to determine the reasonable total radio attenuation (TRA). Also, the pathloss exponent value have a range from 1.06 to 2.94 depending on frequency band and the CMs, which in turn differed with propagation environments. Through this EMSEC-channel analysis, we affirm that the TRA, which is one of the key parameters for determining the security limits for compromising emanations, follows the Rician distribution. However, previous work assumed that radio attenuations would have constant values. We found that the TRA does not show significant differences depending on the frequency bands and has the following range depending on the environment, 29?41dB at CM2, a 42?57 dB at CM3, a 47?57 dB at CM4, and 24?29 at CM5. In addition to, CM3 and CM4 have greater TRA than CM2 and CM5. Based on the experimental results of this study, we propose security limits on periodic as well as aperiodic EMSEC-channel information. The proposed security limits on compromising emanations are classified into two levels according to the TRA and the level of required confidentiality. Periodic emission security limits for class A is 24, 28, 35 dBμV/m in the 100-400 MHz, 400-900 MHz and 900-1000 MHz, respectively. And periodic emission security limits for class B is 4, 1, 3, 5 dBμV/m in the 100-200 MHz, 200-600 MHz, 600-700 MHz and 700-1000 MHz, respectively. Aperiodic emission security limits are weaker than the processing gain Gp, 23 dBi than periodic emission security limits owing to the redundancy caused by repetitive signals. So, that the periodic EMSEC-channel information is easily leaked and reconstructed, which results in a potential risk. Thus, the periodic emission security limits must be stronger than the aperiodic emission security limits. We can then compare our security limits with other security limits and existing civil and military EMC standards. Future works may include characterization and reconstruction of FAX, smartcard and other electronics. And it is need to EMSEC-channel analysis in more complex environments.Chapter 1 Introduction.............................................................1 1.1 Historic background and previous work......................................3 1.2 Motivation and scope...................................................................6 Chapter 2 Detection of Compromising Emanations................9 2.1 Introduction..................................................................................9 2.2 Compromising Emanations from Video Display Units.............10 2.2.1 Property of Video Display Units ..............................................10 2.2.2 Leakage path of Video Display Units........................................11 2.2.3Measurement system...................................................................13 2.2.4 Measurement result....................................................................15 2.3 Compromising Emanations from Printer...................................17 2.3.1 Property of Printer.....................................................................17 2.3.2 Leakage path of Printer..............................................................19 2.3.3 Measurement system..................................................................20 2.3.4 Measurement result....................................................................21 2.4 Conclusion..................................................................................23 Chapter 3 Reconstruction of Compromising Emanations.....25 3.1 Introduction................................................................................25 3.2 EMSEC system for Reconstruction...........................................26 3.3 Reconstruction of Compromising Emanations from Video Display Units....................................................................................26 3.3.1 Characteristics of EMSEC-channel information from VDUs...26 3.3.2 Reconstruction result.................................................................30 3.4 Reconstruction of Compromising Emanations from Printer… 31 3.4.1 Characteristics of EMSEC-channel information from Printer..31 3.4.2 Reconstruction result.................................................................34 3.5 Adaptive Deringing Filter for EMSEC-channel information Reconstruction..................................................................................36 3.6 Conclusion..................................................................................40 Chapter 4 Characteristic of Frequency Correlation EMSEC-Channel in indoor environments............................................42 4.1 Introduction................................................................................42 4.2 Measurement methodology........................................................43 4.2.1 Measurement system..................................................................43 4.2.2 Measurement scenario and environment...................................43 4.3 Analysis of indoor EMSEC-Channel for Compromising Emanations…………………………………..................................46 4.3.1 Frequency correlation property of indoor EMSEC-Channel....47 4.3.2 Pathloss characteristics of indoor EMSEC-Channel.................52 4.4 Conclusion..................................................................................56 Chapter 5 Emission Security Limits for Compromising Emanations.............................................................................58 5.1 Introduction................................................................................58 5.2 Parameters for Emission Security Limits …………………….58 5.2.1 Total radio attenuation...............................................................60 5.2.2 Radio noise.................................................................................65 5.2.3 Antenna gain..............................................................................67 5.2.4 Signal processing gain...............................................................68 5.2.5 Minimum SNR for reconstruction.............................................69 5.2.6 Receiver noise figure.................................................................70 5.2.7 Calculation of emission security limits.....................................71 5.3 Proposed Emission Security Limits...........................................72 5.4 Comparison with Public Standards and Other Security Limits.75 5.4.1 CISPR 22 and MIL-STD-461E.................................................75 5.4.2 Security limits for Markus Kuhn...............................................76 5.4.3 ITU-T K.84 Guidelines..............................................................78 5.5 Conclusion..................................................................................84 Chapter 6 Summary and Further Study.................................86 Bibliography 90 Abstract in Korean.................................................................95Docto