Digital Image Transmission Research Articles

Robust image watermarking in the spatial domain

The rapid evolution of digital image manipulation and transmission techniques has created a pressing need for the protection of the intellectual property rights on images. A copyright protection method that is based on hiding an ‘invisible’ signal, known as digital watermark, in the image is presented in this paper. Watermark casting is performed in the spatial domain by slightly modifying the intensity of randomly selected image pixels. Watermark detection does not require the existence of the original image and is carried out by comparing the mean intensity value of the marked pixels against that of the pixels not marked. Statistical hypothesis testing is used for this purpose. Pixel modifications can be done in such a way that the watermark is resistant to JPEG compression and lowpass filtering. This is achieved by minimizing the energy content of the watermark signal at higher frequencies while taking into account properties of the human visual system. A variation that generates image dependent watermarks as well as a method to handle geometrical distortions are presented. An extension to color images is also pursued. Experiments on real images verify the effectiveness of the proposed techniques.

Subband-coded image reconstruction for lossy packet networks

Transmission of digital subband-coded images over lossy packet networks presents a reconstruction problem at the decoder. This paper presents two techniques for reconstruction of lost subband coefficients, one for low-frequency coefficients and one for high-frequency coefficients. The low-frequency reconstruction algorithm is based on inherent properties of the hierarchical subband decomposition. To maintain smoothness and exploit the high intraband correlation, a cubic interpolative surface is fit to known coefficients to interpolate lost coefficients. Accurate edge placement, crucial for visual quality, is achieved by adapting the interpolation grid in both the horizontal and vertical directions as determined by the edges present. An edge model is used to characterize the adaptation, and a quantitative analysis of this model demonstrates that edges can be identified by simply examining the high-frequency bands, without requiring any additional processing of the low-frequency band. High-frequency reconstruction is performed using linear interpolation, which provides good visual performance as well as maintains properties required for edge placement in the low-frequency reconstruction algorithm. The complete algorithm performs well on loss of single coefficients, vectors, and small blocks, and is therefore applicable to a variety of source coding techniques.

New schemes for progressive transmission of digital images

Two schemes that combine JPEG and segmented image coding (SIC) for the progressive transmission of digital images, are described. Compared to JPEG-based progressive transmission schemes, the new ones produce reconstructed images of better quality across all stages of transmission, while transmitting approximately the same number of bits. The computational complexity of the new schemes is lower than that of the SIC-only approaches.

Digital storage and transmission of cardiovascular images: what are the costs, benefits and timetable for conversion?

Digital storage and transmission of cardiovascular images: what are the costs, benefits and timetable for conversion?

Recent progress in digital image formatting and current trends in computers: their role in digital image storage and telemedicine. Commentary.

This section of Current Opinion in Cardiology is dedicated to recent progress in imaging and echocardiography. Two trends apparent from the five articles in this symposium are the increasing importance of quantitation in cardiovascular imaging and the emergence of new modalities for assessing cardiac structure and function. The exploding volume of imaging data available to the practicing cardiologist has made it increasingly difficult to organize and manage this information in order to obtain an integrated picture of the patient's clinical status. Fortunately, we are also in the midst of a revolution in digital image storage and transmission, which will ease the task of organizing multimodal clinical images and avoiding unnecessary duplication of tests. This commentary reviews important progress in the past year in the development of standardized image formats as well as trends in better computer performance. In echocardiography, ultrasound loops can be stored with calibration data (spatial, temporal, and velocity) to facilitate automated application of some of the new quantitative algorithms outlined by Frank Flachskampf in his article (pp 634-639) [2]. Spatial localizing information can also be stored with the echocardiographic images to facilitate three- and four-dimensional reconstruction of these data. In cineangiography, the DICOM standard codifies methods for storing view orientation, interventional device identification, and the details of contrast administration, facilitating the threedimensional reconstruction and physiological analysis of catheterization data [3]. Finally, in the nuclear cardiology standard, entire protocols involving multiple radioisotopes may be encoded within a single digital study, facilitating the automated display and analysis, for instance, of such data as positron-emission tomography perfusion and metabolic imaging.

Making global telemedicine practical and affordable: demonstrations from the Middle East.

The purpose of this study was to demonstrate the first use of voice-grade telephone lines for the international transmission of both high-resolution digital images (radiology and pathology) and video in near real-time. Eight live demonstrations were performed from the United Arab Emirates and the Kingdom of Saudi Arabia at the invitation of the respective ministries of health. Thirty radiologic studies (CT, MR, and radiographs) were digitized, compressed, and transmitted to Cambridge, MA, where they were interpreted on diagnostic workstations (1792 x 2252 display matrix) by a team of subspecialist radiologists. Near real-time image transmission was achieved by combining wavelet-based image compression (average compression ratio of 23:1) and multiplexing technology that used four phone lines simultaneously. During each demonstration, one pathology image was transmitted from Cambridge to the demonstration site, where it was interpreted by a visiting pathologist. Video-conferencing was implemented with a 64-kilobits-per-sec leased line from the United Arab Emirates and with four multiplexed telephone lines from Saudi Arabia. For teleradiology and telepathology, transmission times ranged from 2-5 min per image. Image fidelity was judged to be of diagnostic quality in all transmitted cases. The video link to the United Arab Emirates was highly reliable. Bandwidth for videoconferencing from Saudi Arabia was marginal on four voice-grade telephone lines, resulting in some downtime (10-20%). Live consultations provided by subspecialists in Cambridge assisted in the management of patients at both venues. The system was well received by both the referring physicians in the Middle East and the participants in the United States. Image compression and multiplexing technologies enabled high-resolution teleradiology and telepathology as well as real-time video consultations over international telephone lines. While telecommunications systems are advancing rapidly in many parts of the world, those areas most in need of telemedicine services are likely to be the last to upgrade their telecommunications infrastructures. This "proof of concept" article outlines a practical and affordable approach that makes telemedicine more accessible to underserved areas worldwide.

GMS雲画像の船舶へのディジタル伝送に関する基礎的研究

GMS雲画像の船舶へのディジタル伝送に関する基礎的研究

Digital image acquisition, processing, and analysis in a polymer microscopy laboratory

In recent years it became apparent that we needed to improve productivity and efficiency in the Microscopy Laboratories in GE Plastics. It was realized that digital image acquisition, archiving, processing, analysis, and transmission over a network would be the best way to achieve this goal. Also, the capabilities of quantitative image analysis, image transmission etc. available with this approach would help us to increase our efficiency. Although the advantages of digital image acquisition, processing, archiving, etc. have been described and are being practiced in many SEM, laboratories, they have not been generally applied in microscopy laboratories (TEM, Optical, SEM and others) and impact on increased productivity has not been yet exploited as well.In order to attain our objective we have acquired a SEMICAPS imaging workstation for each of the GE Plastic sites in the United States. We have integrated the workstation with the microscopes and their peripherals as shown in Figure 1.

IMAGE PROCESSING AND COMPUTER AIDED DIAGNOSIS IN DIGITAL MAMMOGRAPHY: A CLINICAL PERSPECTIVE

Mammographic technology has improved dramatically in the last two decades. The advent of digitally acquired mammograms offers the possibility of further improvements in early breast cancer detection. Specifically, digital acquisition systems decouple the process of X-ray photon detection from image display by using a primary detector that directly quantifies transmitted photons. Digital systems also allow a wide dynamic range so that a wider range of tissue contrast can be appreciated. Digital systems have the capacity to bring revolutionary advantages to breast cancer detection and management (1) image processing for increased lesion conspicuity; (2) computer-aided diagnosis for enhanced radiologic interpretation; (3) teleradiology, or image transmission, as a means of bringing world-class expertise to community hospitals and remote areas; (4) improved image access and communication through digital image archiving and transmission; and (5) dynamic, or “real time” imaging for use during biopsy and localization procedures. In this article, the authors review the literature 011 the use of image processing and computer assisted diagnosis for digital mammography. Future research goals in the development of digital mammography are also discussed.

Digital acoustic video image transmission system for deep‐sea research submergence vehicle ‘‘SHINKAI 6500.’’

High‐speed video image transmission from a research submersible to the mother ship is desirable to facilitate effective deep‐sea research by a submersible. Therefore, a digital acoustic image transmission system was developed, and was installed in the manned deep‐sea research submergence vehicle ‘‘SHINKAI 6500’’ of the Japan Marine Science and Technology Center. This system which adopts 4‐DPSK modulation with a carrier frequency of 20 kHz, has a communication capability of 16 kbit/s and is able to transmit a color‐still image of 256×240 pixels in 8 s. Its communication range is more than 6800 m. In order to transfer a high‐quality color image in a short time, (a) a wide band transducer, that doubles the transmission band, (b) a DCT‐ (discrete cosine transform) based image coding technique that reduces transmission data volume, and (c) an adaptive equalizer and phase controller, that improve communication quality and Doppler compensation, are employed. Results of a performance test (various video images) were successfully received from the ‘‘SHINKAI 6500’’ from a depth of 6500 m to the surface vessel. After a successful performance test, this system will probably be installed in the ‘‘SHINKAI 6500,’’ and new biological or geological experiments will be carried out by the system in the deep sea of the western Pacific Ocean.

ICs for digital image transmission

The digital image transmission IC digitizes and compresses picture signals from a camera for transmission over a twisted paired cable, allowing easy and inexpensive application in household video monitoring systems. Three types of integrated circuits have been developed. An encoder IC which subjects the digitized video signals to data compression and sends and receives control signals; a decoder IC that receives video data from the encoder IC and outputs composite analog video signals; and a hybrid IC which integrates an encoder IC with the majority of its peripheral circuits (including A/D conversion circuits and memory). The main specifications of the three ICs are indicated. >

Concatenated coding scheme with variable coding gain

AbstractThe concatenated coding scheme using convolutional coding with Viterbi decoding for inner code and Reed‐Solomon (RS) code for outer codes is an attractive scheme that can achieve a coding gain larger than that of the convolutional coding with the Viterbi decoding scheme. Hence, it has attracted attention in a wide range of fields in satellite communications from space communications to digital image transmission systems.This paper presents the configuration and characteristics of a newly developed concatenated coding scheme with variable coding gain. This scheme enables selection of a coding gain considering the signal processing time of coding and decoding by enabling selection of: 1) the block length of the RS code (and its error‐correction capability); 2) the depth of interleaving combining the inner and outer code by a single codec. In addition, in this scheme, a new synchronization word detection method was developed and employed. In this method, nonlinear conversion is applied to soft decision demodulated data to synchronize the RS codeword and interleaving. It has been confirmed by numerical calculations that this synchronization word detection method has characteristics further improved over those of the conventional soft decision synchronization word detection method which is superior to the hard decision method. An experimental system was developed and the field test via Ka‐band satellite of communication satellite No. 3 (CS‐3) was performed, and the tradeoff relationships between the coding/decoding signal processing time and coding gain have been clarified quantitatively.

Application of image contours to three aspects of image processing. compression, shape recognition and stereopsis

The value of image contours in three important areas of image processing and analysis is illustrated. The three areas are those of image compression, shape recognition and stereopsis. The compression ratios of classical image coding techniques such as linear prediction and transform coding appear to have reached a saturation level of around 10:1. It is a widely accepted view that radical new coding schemes must be developed if the real-time transmission of digital images is to be achieved. Contours have been used for many years in cartography, where a sparse set of smooth connected curves convey a very accurate impression of the landscape. A method is outlined of storing digital images in terms of their constant intensity contours. As the images are stored directly in terms of the shapes contained within them it is possible to carry out both object recognition and stereopsis using the compressed form of the image. Examples of compression, shape recognition and stereo matching based on contours are presented.

Low-complexity subband coding of still images and video

In many applications involving storage and transmission of digital images, there is an explicit need for data compression. Subband coding has emerged as one suitable technique for satisfying this need. Initially, image subband coders were based on FIR filter banks employing the quadrature mirror filters (QMF) of Johnston. To reduce the complexity associated with these subband coders, we have introduced image subband coders based on two types of IIR filter banks. The first is a tree structured filter bank, whereas the other is a fully parallel construction. The computational complexity ofthese filter banks is examined. The computational complexity of the llR-based structures is significantly lower than their FIR counterparts. Furthermore, we introduce multiplier-free IIR filter banks realizing even further complexity reductions. For the bit-efficient representation of the subband signals of both our still image and video coders, we propose a simple scheme similar to the ones employed for DCT-based coding in the CCITT H.261 recommendation and the emerging ISO/JPEG standard. In demonstrating the performance of our coders, we present simulation results at less than 0.5 bits per pel for still image coding and 64 to 200 kbps for coding of video. The performance of our low-complexity IIR structures is found to be comparable to structures based on FIR filters.

Datenverarbeitung in der Radiologie: Resümee und Ausblick

The technical aspects of radiology are particularly suitable for electronic data processing. In addition to automation of radiological apparatus and tumour registration, there are three areas in radiology particularly suitable for electronic data processing: treatment planning, dose calculations and supervision of radiotherapy techniques in radio-oncology. It can be used for word processing in the office and for documentation, both in diagnostic and therapeutic radiology, and digital techniques can be employed for image transmission, storage and manipulation. Computers for treatment planning and dose calculation are standard techniques and suitable computers allow one to spot occasional and systematic errors during radiation treatment and to eliminate these. They also provide for the automatic generation of the required protocols. Word processors have proved particularly valuable in private practice. They are valuable for composing reports from their basic elements, but less valuable for texts that are stereotypes. The most important developments are in digital imaging, image storage and image transmission. The storage of images on video discs, transmission through fibre-optic cables and computer manipulation of images are described and the consequences and problems, which may affect the radiologist, are discussed.

Perceptual Coding In The Cosine Transform Domain

Source encoding for digital image transmission is revisited with an energy distribution approach in the perceptual domain. Past investigations have utilized power spectral density in conjunction with the Frei eye model and full image Fourier transform coding. In this investigation, the cosine transform is utilized on a partitioned image. A cosine energy function is defined and weighted by the eye model. This results in a circular symmetric form of a bit map which simplifies source coding. This approach outperforms a standard bit allocation procedure allowing graceful degradation at 1, .75, and .5 bits/pixel. Analysis includes the perceptual mean square error and peak signal-to-noise ratio as metrics of performance. This procedure suggests a more rapid hardware implementation.

An Application of the Projection Transform Technique in Image Transmission

Projection transform technique is applied to digital image transmission. Transform samples on various central sections of a Fourier space are attained with a fast Fourier transform algorithm. Quantization, coding, and transmission follow in order. The complete Fourier space information is then, upon reception of signals, estimated from the transform samples at these various central sections. The reconstructed picture is produced by the two-dimensional inverse Fourier transform.

Binary-symmetric-channel error effects on PCM color-image transmission

This paper considers the effects of channel errors on the digital transmission of color images. In the transmission system analyzed, each picture element of a color image is represented by three color components. Two cases are considered: the tristimulus representation and the luminance and chromaticity representation. Each color component is coded with a constant-word-length PCM code and passed through a binary symmetric channel. Channel errors are related to chromaticity and luminance errors in a reconstructed image by the use of color space diagrams. Statistical characteristics of image errors are determined for various color representations. It has been found that if the tristimulus values of a color are transmitted over the channel, the effects of channel errors are to desaturate ali colors toward a mid-gray. For luminance/chromaticity representations, channel errors tend to shift the hue of transmitted colors toward cyan, magenta, or yellow.