Robert Forchheimer

3-D motion estimation in model-based facial image coding

An approach to estimating the motion of the head and facial expressions in model-based facial image coding is presented. An affine nonrigid motion model is set up. The specific knowledge about facial shape and facial expression is formulated in this model in the form of parameters. A direct method of estimating the two-view motion parameters that is based on the affine method is discussed. Based on the reasonable assumption that the 3-D motion of the face is almost smooth in the time domain, several approaches to predicting the motion of the next frame are proposed. Using a 3-D model, the approach is characterized by a feedback loop connecting computer vision and computer graphics. Embedding the synthesis techniques into the analysis phase greatly improves the performance of motion estimation. Simulations with long image sequences of real-world scenes indicate that the method not only greatly reduces computational complexity but also substantially improves estimation accuracy. >

Image coding-from waveforms in animation

The main coding techniques for efficient electronic representation of grayscale images are reviewed. The emphasis is on understanding some of the reasons behind the development of different coding structures. It is shown that various (conscious or unconscious) models of the scene, the image, and the visual system have been and are still being used as the driving source for the construction of coding algorithms. Methods covered in this include delta modulation, predictive coding, transform coding, vector quantization, hybrid coding, subband coding, and semantic image coding. The last two schemes are covered in greater detail. Subband coding forms a bridge between traditional (waveform) concepts and perceptual coding. Semantic coding is an example of a class of new coding techniques based on (3-D) object modeling. >

Image sequence coding at very low bit rates: a review

This paper presents a review of promising techniques for very low bit-rate, below 64 kb/s, image sequence coding. Image sequence coding at such low rates will be a crucial technique in forthcoming visual services, e.g., visual information transmission and storage. A typical application is to transmit moving videophone scenes through the existing analog telephone lines or via a mobile channel. Two types of potential coding techniques are addressed: waveform-based image sequence coding and model-based image sequence coding.

Logic gates based on ion transistors

Precise control over processing, transport and delivery of ionic and molecular signals is of great importance in numerous fields of life sciences. Integrated circuits based on ion transistors would be one approach to route and dispense complex chemical signal patterns to achieve such control. To date several types of ion transistors have been reported; however, only individual devices have so far been presented and most of them are not functional at physiological salt concentrations. Here we report integrated chemical logic gates based on ion bipolar junction transistors. Inverters and NAND gates of both npn type and complementary type are demonstrated. We find that complementary ion gates have higher gain and lower power consumption, as compared with the single transistor-type gates, which imitates the advantages of complementary logics found in conventional electronics. Ion inverters and NAND gates lay the groundwork for further development of solid-state chemical delivery circuits.

Near-sensor image processing: a new paradigm

The paper introduces the concept of near-sensor image processing. By this, the authors mean techniques in which the physical properties of the image sensor itself is utilized to do part of the signal processing task. It is shown that the analog-temporal behavior of photodiodes combined with thresholding amplifiers can be used favorably to do certain low-level image processing tasks including median filtering and convolution. The given examples also show how adaptivity to different light levels can be achieved in a natural way. To extract features from the image, such as moments and shape factors, the authors introduce a simple measurement function.

Eye pupil localization with an ensemble of randomized trees

We describe a method for eye pupil localization based on an ensemble of randomized regression trees and use several publicly available datasets for its quantitative and qualitative evaluation. The method compares well with reported state-of-the-art and runs in real-time on hardware with limited processing power, such as mobile devices. HighlightsA framework for eye pupil localization that compares well with state-of-the-art.Randomization during runtime improves performance.The developed system works in real-time on mobile devices.

Controlling the dimensionality of charge transport in organic thin-film transistors.

Electrolyte-gated organic thin-film transistors (OTFTs) can offer a feasible platform for future flexible, large-area and low-cost electronic applications. These transistors can be divided into two groups on the basis of their operation mechanism: (i) field-effect transistors that switch fast but carry much less current than (ii) the electrochemical transistors which, on the contrary, switch slowly. An attractive approach would be to combine the benefits of the field-effect and the electrochemical transistors into one transistor that would both switch fast and carry high current densities. Here we report the development of a polyelectrolyte-gated OTFT based on conjugated polyelectrolytes, and we demonstrate that the OTFTs can be controllably operated either in the field-effect or the electrochemical regime. Moreover, we show that the extent of electrochemical doping can be restricted to a few monolayers of the conjugated polyelectrolyte film, which allows both high current densities and fast switching speeds at the same time. We propose an operation mechanism based on self-doping of the conjugated polyelectrolyte backbone by its ionic side groups.

MAPP2200: a second-generation smart optical sensor

A new smart optical sensor, the MAPP2200 is presented. It is based on four years of practical experiences with an earlier line sensor device, the LAPP1100. Using a 256*256 array of photo diodes, the new device is capable of capturing a full image. The chip includes circuitry for A/D-conversion and digital image processing. The processor, being a line-parallel SIMD machine, handles line data at a rate of 4 MHz. The device performs common early vision tasks such as filtering, edge detection, histogramming, and correlation at rates of 10 - 100 frames per second. Simpler tasks such as binary template matching can be performed at more than 1000 frames per second. The paper covers both hardware and software aspects of the new device.

Two-view facial movement estimation

This paper addresses the issue of two-view facial motion estimation for model-based facial image coding. A new approach to estimate the motion of the head and the facial expressions is presented, which can be viewed as a two-step procedure as compared with our previous approach. In this new approach M-estimation technique is used to eliminate the effect of the facial expressions on the estimation of the head movement. In this way the global head motion can be more reliably recovered. Once the global motion is obtained, the facial expressions can be estimated. Some experimental results on synthesized and real image sequences demonstrate the effectiveness of the new algorithm. >

Rebounding Droplet‐Droplet Collisions on Superhydrophobic Surfaces: from the Phenomenon to Droplet Logic

When water droplets impact each other while traveling on a superhydrophobic surface, we demonstrate that they are able to rebound like billiard balls. We present elementary Boolean logic operations and a flip-flop memory based on these rebounding water droplet collisions. Furthermore, bouncing or coalescence can be easily controlled by process parameters. Thus by the controlled coalescence of reactive droplets, here using the quenching of fluorescent metal nanoclusters as a model reaction, we also demonstrate an elementary operation for programmable chemistry.