Showing papers in "IEEE Transactions on Circuits and Systems in 2006"

Nuclei Segmentation Using Marker-Controlled Watershed, Tracking Using Mean-Shift, and Kalman Filter in Time-Lapse Microscopy

Abstract: It is important to observe and study cancer cells' cycle progression in order to better understand drug effects on cancer cells. Time-lapse microscopy imaging serves as an important method to measure the cycle progression of individual cells in a large population. Since manual analysis is unreasonably time consuming for the large volumes of time-lapse image data, automated image analysis is proposed. Existing approaches dealing with time-lapse image data are rather limited and often give inaccurate analysis results, especially in segmenting and tracking individual cells in a cell population. In this paper, we present a new approach to segment and track cell nuclei in time-lapse fluorescence image sequence. First, we propose a novel marker-controlled watershed based on mathematical morphology, which can effectively segment clustered cells with less oversegmentation. To further segment undersegmented cells or to merge oversegmented cells, context information among neighboring frames is employed, which is proved to be an effective strategy. Then, we design a tracking method based on modified mean shift algorithm, in which several kernels with adaptive scale, shape, and direction are designed. Finally, we combine mean-shift and Kalman filter to achieve a more robust cell nuclei tracking method than existing ones. Experimental results show that our method can obtain 98.8% segmentation accuracy, 97.4% cell division tracking accuracy, and 97.6% cell tracking accuracy

Electromechanical ΔΣ modulation with high-Q micromechanical accelerometers and pulse density modulated force feedback.

Abstract: This paper presents a comprehensive analysis of force-balanced microelectromechanical modulators for iner- tial and force sensing applications, with the emphasis on the control of high-Q micromechanical accelerometers. High Q is desirable for reducing thermal-mechanical Brownian noise but makes the control more challenging. Linear multibit force feedback using nonlinear actuators based on pulse density modulation (PDM) is described. The characteristics of the modulators, including stability, quantization noise, dynamic range, and proof-mass posi- tion error, are studied by simulations. The effects of nonidealities such as proof-mass position offset, manufacturing variations and undesired vibration modes are investigated.

A 200-Mbps 2-Gbps Continuous-Rate Clock-and-Data-Recovery Circuit

Abstract: A 200-Mbps 2-Gbps continuous-rate clock-and- data-recovery (CDR) circuit using half-rate clocking is pre- sented. To detect the data with wide-range bit rates, a frequency tracing circuit (FTC) is used to aid the frequency acquisition. A wide-range and low gain voltage-controlled oscillator (VCO) is also presented by using analog and digital controlled mechanisms. A two-level bang-bang phase detector is utilized to improve the jitter performance and speed up the locking process. This CDR circuit has been realized in a 2P4M 0.35- m CMOS process. The experimental results show that this CDR circuit with the proposed FTC can receive pseudorandom bit stream when the bit rate ranges from 200 Mbps to 2 Gbps without the harmonic-locking issue. All measured bit error rates are below . The measured root-mean-square and peak-to-peak jitters are 5.86 ps and 41.8 ps, respectively, at 2 Gbps. Index Terms—Clock-and-data-recovery (CDR), continuous rate, frequency detector, voltage-controlled oscillator (VCO).

Tunable continuous-time bandpass ΣΔ modulators with fractional delays.

Abstract: An analytical design methodology for continuous- time (CT) bandpass (BP) modulators is presented. Second- and fourth-order tunable continuous time BP modulator design equations are presented. A novel loop architecture, where the traditional CT BP loop filter function is replaced with the filter function with fractional delays, is proposed. Validity of the methodology is confirmed by mixed-signal behavioral simulations.

Geometrical analysis of puppet-theater and cardboard effects in stereoscopic HDTV images

Abstract: A fundamental element of stereoscopic image production is to geometrically analyze the conversion from real space to stereoscopic images by binocular parallax under various shooting and viewing conditions. This paper reports on this analysis, particularly on the setting of the optical axes of three-dimensional (3-D) cameras, which has received little attention in the past. First, we identified the conditions for setting the optical axes that maintain linearity during the conversion from real space to stereoscopic images. We then clarified, in geometrical terms, the shooting and viewing conditions and also conditions under which the puppet-theater effect and cardboard effect occur. The results showed that the parallel camera configuration, by which optical axes are kept parallel to each other, does not produce the puppet-theater effect as the apparent magnification (lateral magnification) of a shooting target is not dependent on the shooting distance. However, the toed-in camera configuration, where the apparent magnification of a shooting target is dependent on the shooting distance, may produce this effect. The cardboard effect is shown to be likely to occur for both camera configurations by defining this phenomenon by the ratio of depthwise reproduction magnification (depth magnification) and apparent reproduction magnification (lateral magnification). Lastly, the paper reports on the relationship between the results of this analysis and those of subjective evaluation experiments. The results need a closer examination by using many more images.

Robustness enhancement for noncentric quantization based image watermarking

Abstract: This paper presents a novel approach for improving the robustness of the quantization-based watermarking scheme. Unlike the conventional approach, which quantizes the host value to the center of the objective interval, the proposed scheme offers the flexibility of determining the quantized value. Given tolerable embedding-induced distortion and the host value, the quantized value can be analytically determined in a closed-form solution, instead of being fixed at the center of the interval. To objectively compare the robustness, different watermarking schemes are implemented in the same distortion-to-noise ratio (DNR) scenario and then the probabilities of error detection are measured. Simulation results indicate that the proposed scheme, compared to the conventional quantization watermarking, could reduce the error probability by 0.113 when DNR is set to 0 dB, whereas the reduction is only 0.037 for the recent Wu's approach. Furthermore, without the finite possible values of the watermarked data, the proposed scheme provides sufficient nondisclosure for the quantization step, whereas in the conventional quantization-based watermarking, the quantization step can be easily inferred from the watermarked data