Continuous Tone Research Articles

Analysis on Adjusting Effect and Spectral Characteristics of Digital Image Sampling

When it comes to the digitized image, it is a process of converting analog image of continuous tone which has been sampled and quantized into digital image. The application of digital technology in modern art has become one of the hot spot in this field. First of all, this paper undertakes the digital image process of image. According to the filtering properties of the Dirac function, this paper analyzes the two-dimensional sampling principle of digital image. Based on this, the relationship between image spectrum before sampling and after sampling is compared and analyzed according to the related properties of Fourier transform. And then it is obtained that it is concluded that the ideal low-pass filter can make the sample undistorted. By further analyzing the error of the sampling value quantification processing, the rebuilt best quantitative values of image can be obtained. Thats to say, the reconstruction of digital image is the inverse process of image sampling. To a certain extent, it provides scientific theoretical basis for the integration of digital image in modern art design.

Scanned image descreening with image redundancy and adaptive filtering.

Currently, most electrophotographic printers use halftoning technique to print continuous tone images, so scanned images obtained from such hard copies are usually corrupted by screen like artifacts. In this paper, a new model of scanned halftone image is proposed to consider both printing distortions and halftone patterns. Based on this model, an adaptive filtering based descreening method is proposed to recover high quality contone images from the scanned images. Image redundancy based denoising algorithm is first adopted to reduce printing noise and attenuate distortions. Then, screen frequency of the scanned image and local gradient features are used for adaptive filtering. Basic contone estimate is obtained by filtering the denoised scanned image with an anisotropic Gaussian kernel, whose parameters are automatically adjusted with the screen frequency and local gradient information. Finally, an edge-preserving filter is used to further enhance the sharpness of edges to recover a high quality contone image. Experiments on real scanned images demonstrate that the proposed method can recover high quality contone images from the scanned images. Compared with the state-of-the-art methods, the proposed method produces very sharp edges and much cleaner smooth regions.

Dual‐color mixing for fused deposition modeling printers

AbstractIn this work we detail a method that leverages the two color heads of recent low‐end fused deposition modeling (FDM) 3D printers to produce continuous tone imagery. The challenge behind producing such two‐tone imagery is how to finely interleave the two colors while minimizing the switching between print heads, making each color printed span as long and continuous as possible to avoid artifacts associated with printing short segments. The key insight behind our work is that by applying small geometric offsets, tone can be varied without the need to switch color print heads within a single layer. We can now effectively print (two‐tone) texture mapped models capturing both geometric and color information in our output 3D prints.

An error diffusion based method to generate functionally graded cellular structures

The spatial variation of cell size in a functionally graded cellular structure is achieved using error diffusion to convert a continuous tone image into binary form. Effects of two control parameters, greyscale value and resolution on the resulting cell size measures were investigated. Variation in cell edge length was greatest for the Voronoi connection scheme, particularly at certain parameter combinations. Relationships between these parameters and cell size were identified and applied to an example, where the target was to control the minimum and maximum cell size. In both cases there was an 8% underestimation of cell area for target regions.

A Multifrequency Radar System for Detecting Humans and Characterizing Human Activities for Short-Range Through-Wall and Long-Range Foliage Penetration Applications

A multifrequency radar system for detecting humans and classifying their activities at short and long ranges is described. The short-range radar system operates within the S-Band frequency range for through-wall applications at distances of up to 3 m. It utilizes two separate waveforms which are selected via switching: a wide-band noise waveform or a continuous single tone. The long-range radar system operating in the W-Band millimeter-wave frequency range performs at distances of up to about 100 m in free space and up to about 30 m through light foliage. It employs a composite multimodal signal consisting of two waveforms, a wide-band noise waveform and an embedded single tone, which are summed and transmitted simultaneously. Matched filtering of the received and transmitted noise signals is performed to detect targets with high-range resolution, whereas the received single tone signal is used for the Doppler analysis. Doppler measurements are used to distinguish between different human movements and gestures using the characteristic micro-Doppler signals. Our measurements establish the ability of this system to detect and range humans and distinguish between different human movements at different ranges.

Probing the sensory effects of involuntary attention change by ERPs to auditory transients

An auditory selective attention set allows one to enhance the processing of goal-relevant sound events, which is reflected by the enhancement of the N1 event-related potential (ERP). The present study investigated whether the sensory consequences of distraction (i.e., involuntary attention changes triggered by infrequent sensory events) can be revealed as the removal of this attentional ERP enhancement. Continuous tones featuring occasional gaps were presented, and participants performed a gap-detection task. Independently from gaps, abrupt pitch changes (glides) were introduced, either rarely or frequently, in separate conditions. Whereas rare glides preceding gaps by 150 ms strongly impacted gap-detection performance and gap-related N1 amplitudes, their impact on gaps following rare glides by 650 ms was significantly smaller in both measures. This result demonstrates the utility of N1 in probing the sensory impact of auditory distraction.

Melodic algorithms for pulse oximetry to allow audible discrimination of abnormal systolic blood pressures

An anesthesiologist must remain vigilant of the patient's clinical status, incorporating many independent physiological measurements. Oxygen saturation and heart rate are represented by continuous audible tones generated by the pulse oximeter, a mandated monitoring device. Other important clinical parameters--notably blood pressure--lack any audible representation beyond arbitrarily-configured threshold alarms. Attempts to introduce further continuous audible tones have apparently foundered; the complexity and interaction of these tones have exceeded the ability of clinicians to interpret them. Instead, we manipulate the tonal and rhythmic structure of the accepted pulse oximeter tone pattern melodically. Three melodic algorithms were developed to apply tonal and rhythmic variations to the continuous pulse oximeter tone, dependent on the systolic blood pressure. The algorithms distort the original audible pattern minimally, to facilitate comprehension of both the underlying pattern and the applied variations. A panel of anesthesia practitioners (attending anesthesiologists, residents and nurse anesthetists) assessed these algorithms in characterizing perturbations in cardiopulmonary status. Twelve scenarios, incorporating combinations of oxygen desaturation, bradycardia, tachycardia, hypotension and hypertension, were tested. A rhythmic variation in which additional auditory information was conveyed only at halftime intervals, with every other "beat" of the pulse oximeter, was strongly favored. The respondents also strongly favored the use of musical chords over single tones. Given three algorithms of tones embedded in the pulse oximeter signal, anesthesiologists preferred a melodic tone to signal a significant change in blood pressure.

Psychoacoustic Assessment to Improve Tinnitus Diagnosis

The diagnosis of tinnitus relies on self-report. Psychoacoustic measurements of tinnitus pitch and loudness are essential for assessing claims and discriminating true from false ones. For this reason, the quantification of tinnitus remains a challenging research goal. We aimed to: (1) assess the precision of a new tinnitus likeness rating procedure with a continuous-pitch presentation method, controlling for music training, and (2) test whether tinnitus psychoacoustic measurements have the sensitivity and specificity required to detect people faking tinnitus. Musicians and non-musicians with tinnitus, as well as simulated malingerers without tinnitus, were tested. Most were retested several weeks later. Tinnitus pitch matching was first assessed using the likeness rating method: pure tones from 0.25 to 16 kHz were presented randomly to participants, who had to rate the likeness of each tone to their tinnitus, and to adjust its level from 0 to 100 dB SPL. Tinnitus pitch matching was then assessed with a continuous-pitch method: participants had to match the pitch of their tinnitus to an external tone by moving their finger across a touch-sensitive strip, which generated a continuous pure tone from 0.5 to 20 kHz in 1-Hz steps. The predominant tinnitus pitch was consistent across both methods for both musicians and non-musicians, although musicians displayed better external tone pitch matching abilities. Simulated malingerers rated loudness much higher than did the other groups with a high degree of specificity (94.4%) and were unreliable in loudness (not pitch) matching from one session to the other. Retest data showed similar pitch matching responses for both methods for all participants. In conclusion, tinnitus pitch and loudness reliably correspond to the tinnitus percept, and psychoacoustic loudness matches are sensitive and specific to the presence of tinnitus.

Tinnitus Loudness Tracking: A “Type V Békésy” Pattern Does Not Exist for Pseudotinnitus

Evaluation tools are lacking for the identification of patients exhibiting pseudotinnitus. It was hypothesized that tinnitus loudness traces might show a separation between continuous and pulsed tones for participants exhibiting pseudotinnitus, that is, the "type V" pattern shown for threshold tracking among participants exhibiting pseudohypacusis. It was further hypothesized that tinnitus loudness tracking might reveal unreliable tinnitus loudness matches among participants exhibiting pseudotinnitus due to their lack of an internal tinnitus standard. To determine whether a tinnitus loudness tracking pattern exists for participants exhibiting pseudotinnitus. Nonrandomized posttest-only control design. The experimental group participants were those without tinnitus, and the control group participants were those with tinnitus. There were 86 participants, including 45 with tinnitus and 41 without tinnitus. The participants' hearing varied from normal to severe hearing losses by pure-tone average at 1000, 2000, and 4000 Hz. Participants without tinnitus were asked to act as if they had tinnitus and to complete tinnitus loudness matching as if they were trying to convince the test (or computer) that they had tinnitus. t-tests There were no statistically significant differences between individuals with tinnitus and participants acting out pseudotinnitus for any of six measures: (1) continuous tone tinnitus loudness tracking; (2) pulsed tone tinnitus loudness tracking; (3) differences between continuous and pulsed tone tinnitus loudness tracking; (4) continuous tone excursion width; (5) pulsed tone excursion width; and (6) differences between continuous and pulsed tone excursion width. Tinnitus loudness tracking does not appear to hold promise as a clinical tool for the identification of participants exhibiting pseudotinnitus.

Hearing frequency thresholds of a harbor porpoise (Phocoena phocoena) temporarily affected by a continuous 1.5 kHz tone

Harbor porpoises may suffer hearing loss when exposed to intense sounds. After exposure to a 1.5 kHz continuous tone without harmonics at a mean received sound pressure level of 154 dB re 1 μPa for 60 min (cumulative sound exposure level: 190 dB re 1 μPa(2) s), the temporary hearing threshold shift (TTS) of a porpoise was quantified at 1.5, 2, 4, 6.5, 8, 16, 32, 63, and 125 kHz with a psychoacoustic technique. Significant TTS only occurred at 1.5 and 2 kHz. Mean TTS (1-4 min after sound exposure stopped) was ~14 dB at 1.5 kHz and ~11 dB at 2 kHz, and recovery occurred within 96 min. Control hearing tests before and after a 60 min low ambient noise exposure showed that normal variation in TTS was limited (standard deviation: ± 1.0 dB). Ecological effects of TTS depend not only on the magnitude of the TTS, its duration (depending on the exposure duration), and the recovery time after the exposure stopped, but also on the hearing frequency affected by the fatiguing noise. The hearing thresholds of harbor porpoises for the frequencies of their echolocation signals are not affected by intense low frequency sounds, therefore these sounds are unlikely to affect foraging efficiency.

Audiogram and auditory critical ratios of two Florida manatees (Trichechus manatus latirostris)

This Corrigendum relates to J. Exp. Biol. 215, 1442-1447.The authors misunderstood JEB's policies on citing non-peer-reviewed literature, and failed to cite the dissertation of Gerstein (Gerstein, 1999), who also measured critical ratios in two captive manatees.Gerstein measured critical ratios using both pulsed and continuous (4 s) tones in the presence of 1/3-octave wide masking noise using two different noise levels. The critical ratios were lower for the pulsed tones than the continuous tone. Although we did not test the same frequencies, our measurements of critical ratios in two other manatees were similar or lower for similar test frequencies for the continuous tone. For example, we measured critical ratios from two manatees at 4 kHz of 30.8 and 29.9 dB, while Gerstein measured critical ratios at 3 kHz of 31 and 34 dB. At 16 kHz we measured critical ratios of 27.0 and 28.1 dB, while Gerstein measured critical ratios of 38 and 42 dB at 18 kHz. The results Gerstein obtained for the pulsed tones were closer to the critical ratios we measured with the 1 s tone. The differences in results could be due to differences between individuals or methods used in the two studies. They are unlikely to be due to differences in the masking noise, because the bandwidth of masking noise used in our experiments was wider.The authors apologise to Dr Gerstein, the journal editors and the readership for any inconvenience this may have caused but assure readers that it does not affect the data, results, interpretations or conclusions of the paper.The journal received a letter of concern relating to a lack of acknowledgement of a previous body of research in J. Exp. Biol. 215, 1442-1447. After contacting the authors of the paper, the journal asked The University of South Florida, USA, to carry out an investigation. The outcome of this investigation indicated no evidence of misconduct.

A PREDICTIVE CODING METHOD FOR LOSSLESS COMPRESSION OF IMAGES

Images are an important part of today's digital world. However, due to the large quantity of data needed to represent modern imagery the storage of such data can be expensive. Thus, work on efficient image storage (image compression) has the potential to reduce storage costs and enable new applications.This lossless image compression has uses in medical, scientific and professional video processing applications.Compression is a process, in which given size of data is compressed to a smaller size. Storing and sending images to its original form can present a problem in terms of storage space and transmission speed.Compression is efficient for storing and transmission purpose.In this paper we described a new lossless adaptive prediction based algorithm for continuous tone images. In continuous tone images spatial redundancy exists.Our approach is to develop a new backward adaptive prediction techniques to reduce spatial redundancy in a image.The new prediction technique known as Modifed Gradient Adjusted Predictor (MGAP) is developed. MGAP is based on the prediction method used in Context based Adaptive Lossless Image Coding (CALIC). An adaptive selection method which selects the predictor in a slope bin in terms of minimum entropy improves the compression performance.

Time-correspondence differential ghost imaging

Experimental data with digital masks and a theoretical analysis are presented for an imaging scheme that we call time-correspondence differential ghost imaging (TCDGI). It is shown that by conditional averaging of the information from the reference detector but with the negative signals inverted, the quality of the reconstructed images is in general superior to all other ghost imaging (GI) methods to date. The advantages of both differential GI and time-correspondence GI are combined, plus less data manipulation and shorter computation time are required to obtain equivalent quality images under the same conditions. This TCDGI method offers a general approach applicable to all GI techniques, especially when objects with continuous gray tones are involved.

Continuous Tone Colour Printing in Two and a Half Dimensions Through a Combination of 19<sup>th</sup> Century Analogue Methodologies and 3D Printing

This paper proposes a contemporary method of continuous tone colour printing based upon the Nineteenth Century printing process of Woodburytype as developed by Walter Bentley Woodbury in 1865. Woodburytype was the only truly continuous tone printing process yet invented, and died out in the late nineteenth century as more expedient and cost effective methods of printing prevailed, thus laying the path for current CMYK print technologies. Digital print itself, since its development as a range of colour printing technologies, has followed a route based on the half-tone dot and four colour separation predicated around CMYK. In recent years stochastic algorithms and dithering have allowed the lay down of multiple passes and colour sets to create a near continuous tone image. The downside of this approach is that in order to create a full colour subtractive image, the resultant prints have very little surface topography and a mechanical uniformity that demonstrates none of the surface characteristics, tactile qualities and rich tonal warmth of the 19th century photomechanical processes.Current research at the Centre for Fine Print Research (CFPR) at the University of the West of England, Bristol, is exploring the potential of CNC milled imagery, where the tonal range of each colour is assigned a physical height to produce a continuous tone topographic relief printing matrix, from which the colour image is cast in a silicone ink. A translucent image is cast from each of the colour matrices and each colour is assembled one on top of another resulting in a true four colour separation continuous tone print, where colour tone is created by physical depth of colour.

Exploiting biomechanical degrees of freedom for fast and accurate changes in movement direction: coordination underlying quick bow reversals during continuous cello bowing.

Theoretical and empirical evidence suggests that accurate and efficient motor performance may be achieved by task-specific exploitation of biomechanical degrees of freedom. We investigate coordination of the right arm in a task requiring a sudden yet precisely controlled reversal of movement direction: bow reversals during continuous (“legato”) tone production on a stringed instrument. Ten advanced or professional cello players (at least 10 years of practice) and ten age-matched novice players took part in the study. Kinematic data from the bow and the right arm were analyzed in terms of velocity and acceleration profiles, as well as temporal coordination along the arm. As expected, experts' bow velocity and acceleration profiles differed markedly from those of novice participants, with higher peak accelerations and quicker direction changes. Importantly, experts achieved the change in movement direction with a single acceleration peak while novices tended to use multiple smaller acceleration peaks. Experts moreover showed a proximal-distal gradient in timing and amplitudes of acceleration peaks, with earlier and lower-amplitude reversals at more proximal joints. We suggest that this coordination pattern allows generating high accelerations at the end effector while reducing the required joint torques at the proximal joints. This may underlie experts' ability to produce fast bow reversals efficiently and with high spatiotemporal accuracy. The findings are discussed in terms of motor control theory as well as potential implications for musicians' performance and health.

LumeJet - a new Photonic ‘Inkless’ Printing Technology

The result of 10 years of research, LumeJet is bringing to market a new photonic ‘inkless’ technology for ultra high quality printing and patterning applications. Similar to Ink Jet – but without the inks – LumeJet comprises custom designed print heads (moving or static) with multi-LED arrays and special fiber taper optics. Using light, rather than ink, increases throughput and image quality, whilst reducing media costs. LumeJet is a continuous tone process that can resolve down to 1pt colored text and graphics, which would require at least 8-colours and over 4000dpi with inkjet and toner systems. Applications for LumeJet technology have also been identified in label and package printing and printed electronics.

A Simplified Overprint Model and Why the Masking Equations “Sort Of” Work for Color Halftone Hardcopy

The linear masking equations, inspired by continuous tone photographic color, were applied by Murray, et al., to halftone printing. This model is considerably simpler than models customarily used for halftone color hardcopy, such as those based on Neugebauer. Despite unrealistic assumptions regarding the image microstructure, the masking equations often perform reasonably well.In this paper, the differences between the linear masking model and the model of Yule and Colt (Neugebauer with wideband Yule-Nielsen correction applied) are parsed. It is shown that, under conditions for which the Yule-Nielsen parameter n grows without bound (or its reciprocal, u, approaches zero), the differences can be attributed to sub-additivity of densities. An approximation is offered to model the sub-additivities.The largest difference between the two models can be expected to occur under normal circumstances when all colorants are printed solid.

Behavioral evidence for auditory induction in a species of rodent: Mongolian gerbil (Meriones unguiculatus)

When a segment of sound of interest is interrupted by a loud extraneous noise, humans perceive that the missing sound continues during the intrusive noise. This restoration of auditory information occurs in perceptions of both speech and non-speech sounds (e.g., tone bursts), a phenomenon referred to as auditory induction. In this study, Mongolian gerbils were trained with standard Go/No-Go operant conditioning to discriminate continuous tone bursts (the Go stimulus) from tone bursts with a silent gap in the middle (the No-Go stimulus). Noise was added to Go and No-Go stimuli to determine the condition under which induction would occur. The Mongolian gerbils engaged in Go responses to No-Go stimuli only when the noise spectrally surrounding the tone was of the same duration as the silent portion of the No-Go stimulus; these results match those previously reported in primates (humans and macaque monkeys). The result presents not only the evidence of the auditory induction in a rodent species but also suggests that similar mechanisms for restoring missing sounds are shared among mammals. Additionally, our findings demonstrated that the rodent can serve as a valuable animal model for future studies of perceptual restoration.

Repeated exposure to a tone transiently alters spectral tuning bandwidth of neurons in the central nucleus of inferior colliculus in juvenile rats

Early acoustic experience changes tonal frequency tuning in the inferior colliculus (IC) and the primary auditory cortex. The contributions of IC plasticity to cortical frequency map reorganization are not entirely clear. While most cortical plasticity studies exposed animals to pulsed tones, studies of IC plasticity used either noise or a continuous tone. Here we compared the effects of repeated exposure to single-frequency tone pips on cortical and IC frequency representations in juvenile rats. We found that while tone exposure caused a long-lasting increase in cortical representations of the exposure frequency, changes to IC neurons were limited to a transient narrowing of tuning bandwidth. These results suggest that previously documented cortical frequency map reorganization does not depend on similar changes in the subcortical auditory nuclei.

Digital reconstruction of halftoned color comics

We introduce a method for automated conversion of scanned color comic books and graphical novels into a new high-fidelity rescalable digital representation. Since crisp black line artwork and lettering are the most important structural and stylistic elements in this important genre of color illustrations, our digitization process is geared towards faithful reconstruction of these elements. This is a challenging task, because commercial presses perform halftoning (screening) to approximate continuous tones and colors with overlapping grids of dots. Although a large number of inverse haftoning (descreening) methods exist, they typically blur the intricate black artwork. Our approach is specifically designed to descreen color comics, which typically reproduce color using screened CMY inks, but print the black artwork using non-screened solid black ink. After separating the scanned image into three screening grids, one for each of the CMY process inks, we use non-linear optimization to fit a parametric model describing each grid, and simultaneously recover the non-screened black ink layer, which is then vectorized. The result of this process is a high quality, compact, and rescalable digital representation of the original artwork.