Resolution Color Research Articles

Of ghrelin, cone cultivation, dinoflagellate eyes, and the cyanobacterial circadian clock.

Of ghrelin, cone cultivation, dinoflagellate eyes, and the cyanobacterial circadian clock.

Superpixel based fusion and demosaicing for multi-focus Bayer images

In this paper, a novel superpixel based multi-focus image fusion algorithm for raw images of single-sensor color imaging devices which incorporates the Bayer pattern is proposed. The proposed algorithm is more efficient than traditional fusion schemes since the raw Bayer pattern images are fused before color demosaicing. With the proposed fusion algorithm, the interpolation errors introduced by the repeated demosaicing operation on multi-source images can also be greatly reduced. In detail, a clarity measurement of Bayer pattern image is defined to judge the focus-level of raw Bayer pattern images, and the fusion operator is performed on superpixels which provide powerful grouping cues of local image feature. By comparing the clarities of superpixels, a weight map is constructed and the guided filter is utilized to refine the weight map. The raw images are merged with refined weight map to get the fused Bayer pattern image, which is restored by the demosaicing algorithm to get the full resolution color image. Experimental results demonstrate that the proposed algorithm can obtain better fused results with more natural appearance and fewer artifacts than the traditional algorithms.

Technology and Technique Standards for Camera-Acquired Digital Dermatologic Images: A Systematic Review.

Photographs are invaluable dermatologic diagnostic, management, research, teaching, and documentation tools. Digital Imaging and Communications in Medicine (DICOM) standards exist for many types of digital medical images, but there are no DICOM standards for camera-acquired dermatologic images to date. To identify and describe existing or proposed technology and technique standards for camera-acquired dermatologic images in the scientific literature. Systematic searches of the PubMed, EMBASE, and Cochrane databases were performed in January 2013 using photography and digital imaging, standardization, and medical specialty and medical illustration search terms and augmented by a gray literature search of 14 websites using Google. Two reviewers independently screened titles of 7371 unique publications, followed by 3 sequential full-text reviews, leading to the selection of 49 publications with the most recent (1985-2013) or detailed description of technology or technique standards related to the acquisition or use of images of skin disease (or related conditions). No universally accepted existing technology or technique standards for camera-based digital images in dermatology were identified. Recommendations are summarized for technology imaging standards, including spatial resolution, color resolution, reproduction (magnification) ratios, postacquisition image processing, color calibration, compression, output, archiving and storage, and security during storage and transmission. Recommendations are also summarized for technique imaging standards, including environmental conditions (lighting, background, and camera position), patient pose and standard view sets, and patient consent, privacy, and confidentiality. Proposed standards for specific-use cases in total body photography, teledermatology, and dermoscopy are described. The literature is replete with descriptions of obtaining photographs of skin disease, but universal imaging standards have not been developed, validated, and adopted to date. Dermatologic imaging is evolving without defined standards for camera-acquired images, leading to variable image quality and limited exchangeability. The development and adoption of universal technology and technique standards may first emerge in scenarios when image use is most associated with a defined clinical benefit.

Time-of-Flight Sensor Calibration for a Color and Depth Camera Pair.

We present a calibration method of a time-of-flight (ToF) sensor and a color camera pair to align the 3D measurements with the color image correctly. We have designed a 2.5D pattern board with irregularly placed holes to be accurately detected from low resolution depth images of a ToF camera as well as from high resolution color images. In order to improve the accuracy of the 3D measurements of a ToF camera, we propose to perform ray correction and range bias correction. We reset the transformation of the ToF sensor which transforms the radial distance into the scene depth in Cartesian coordinate through ray correction. Then we capture a planar scene from different depths to correct the distance error that is shown to be dependent not only on the distance but also on the pixel location. The range error profiles along the calibrated distance are classified according to their wiggling shapes and each cluster of profiles with similar shape are separately estimated using a B-spline function. The standard deviation of the remaining random noise is recorded as an uncertainty information of distance measurements. We show the performance of our calibration method quantitatively and qualitatively on various datasets, and validate the impact of our method by demonstrating an RGB-D shape refinement application.

The New Italian Glacier Inventory: a didactic tool for a better knowledge of the natural Alpine environment

A glacier inventory is an important instrument to better know the Alpine glacierized environment. After the glacier inventory realized by the Comitato Glaciologico Italiano (CGI, 1959-1962), only regional and local glacier inventories have been developed. In this work, we briefly present the New Italian Glacier Inventory which has been developed by analyzing high resolution color orthophotos acquired in the 2005-2011 time frame. In the New Italian Glacier Inventory 903 glaciers are listed, covering a total area of 369.90 km 2 . The largest part of the glacier area is located in the Aosta Valley Region (36.15% of the total), followed by the Lombardy Region (23.71%) and by the Province of Bolzano (23.01%). The highest number of glaciers is in Lombardy (230), followed by the Province of Bolzano (212), the Region of Aosta Valley (192), the Province of Trento (115). About 84% of the total glacier inventory is given by glaciers under 0.5 km 2 covering only 21% of the total area. Glaciers wider than 1 km 2 are about 9.4% of the inventory, but they cover 67.8% of the total area. In the biggest size class (>10 km 2 ) three glaciers are found. Only 25 glaciers (2.8% of the census as a whole) were classified as “valley glacier” and the largest part (57.3%) was classified as “mountain glacier” and “glacieret” (40%), confirming that the Italian glacier resource is distributed into many small ice bodies with only a few large glaciers.

Get the LED Out: Experimental Validation of a Capacitor-Free Single-Inductor, Multiple-Output LED Driver Topology

This article presents a new approach for driving multicolor red-green-blue-white ( RGBW) high-current light-emitting diodes (LEDs) for general lighting. The physical advantages in LED applications can be improved by elementary changes in the topology. The presented prototype demonstrator has superior advantages in complexity, form factor, and cost compared to state-of-the-art multicolor LED drivers. A single inductor in parallel to the LED strings is used to supply multiple different LED strings without additional output capacitors. For energy efficiency, the well-known continuous and discontinuous conduction modes (CCM and DCM) are implemented. A novel all-digital current control strategy is used so that no voltage measurements have to be performed, even for light load detection or idle time control in DCM. The irrelevance of any voltage control and the negligence of storage capacitors dramatically reduce the system?s form factor and increase the LED driver reliability. Dimming has been applied with hybrid amplitude and pulsewidth modulation (AM-PWM) control. Thus, color mixing is done by a continuous time integral of the discrete LED light spectra. A discrete prototype demonstrator has been implemented, and further constraints to develop a full integrated circuit (IC) are being evaluated. The discrete demonstrator runs at 12-V dc input voltage with a maximum current of 200 mA to run high-current RGBW LED strings. The peak efficiency of 77.5% is limited by the choice of the applied N-type metal-oxide-semiconductor (NMOS) transistors, which are special and unique on the market for this topology. The high switching frequency of above 1 MHz during CCM ensures a flicker-free color resolution of above 10 b.

The influence of slope and peatland vegetation type on riverine dissolved organic carbon and water colour at different scales

Peatlands are important sources of fluvial carbon. Previous research has shown that riverine dissolved organic carbon (DOC) concentrations are largely controlled by soil type. However, there has been little work to establish the controls of riverine DOC within blanket peatlands that have not undergone major disturbance from drainage or burning. A total of 119 peatland catchments were sampled for riverine DOC and water colour across three drainage basins during six repeated sampling campaigns. The topographic characteristics of each catchment were determined from digital elevation models. The dominant vegetation cover was mapped using 0.5m resolution colour infrared aerial images, with ground-truthed validation revealing 82% accuracy. Forward and backward stepwise regression modelling showed that mean slope was a strong (and negative) determinant of DOC and water colour in blanket peatland river waters. There was a weak role for plant functional type in determining DOC and water colour. At the basin scale, there were major differences between the models depending on the basin. The dominance of topographic predictors of DOC found in our study, combined with a weaker role of vegetation type, paves the way for developing improved planning tools for water companies operating in peatland catchments. Using topographic data and aerial imagery it will be possible to predict which tributaries will typically yield lower DOC concentrations and which are therefore more suitable and cost-effective as raw water intakes.

Focus on lasers and imaging

Focus on lasers and imaging

Browsing Software of the Visible Korean Data Used for Teaching Sectional Anatomy

The interpretation of computed tomographs (CTs) and magnetic resonance images (MRIs) to diagnose clinical conditions requires basic knowledge of sectional anatomy. Sectional anatomy has traditionally been taught using sectioned cadavers, atlases, and/or computer software. The computer software commonly used for this subject is practical and efficient for students but could be more advanced. The objective of this research was to present browsing software developed from the Visible Korean images that can be used for teaching sectional anatomy. One thousand seven hundred and two sets of MRIs, CTs, and sectioned images (intervals, one millimeter) of a whole male cadaver were prepared. Over 900 structures in the sectioned images were outlined and then filled with different colors to elaborate each structure. Software was developed where four corresponding images could be displayed simultaneously; in addition, the structures in the image data could be readily recognized with the aid of the color‐filled outlines. The software, distributed free of charge, could be a valuable tool to teach medical students. For example, sectional anatomy could be taught by showing the sectioned images with real color and high resolution. Students could then review the lecture by using the sectioned and color‐filled images on their own computers. Students could also be evaluated using the same software. Furthermore, other investigators would be able to replace the images for more comprehensive sectional anatomy.

The Correlation Between Blood Oxygenation Effects and Human Emotion Towards Facial Skin Colour of Virtual Human

The quest for determining the glamorous conditions of the human facial skin based on the texture, color, health perception, races, age and charm is never-ending. Manifestation of facial skin is subjected to the physical and physiological state of human emotions. The facial expression and appearance alters as we move, talk, think and endure stress under constant flux. The colors of skin is one of the key indicators of these changes and the color resolution is decided by the scattering and absorption of light within the skin layers containing chromophores in the melanin and hemoglobin oxygenation in the blood. Understanding the facial color distribution, homogeneity of the pigmentation or skin quality under stimuli are the key issues. We examine the correlation between blood oxygenation in changing facial skin color and basic natural emotional expressions such as angry, happy, sad and fear using the Pulse Oximetry and 3D skin analyzer. The data from seven subjects with three female of age 17, 25 and 35 years, four male of 22, 30, 36, 40 years under different number of partially extreme facial expressions are feed in the new dynamic model for simulation. Experimental results are analyzed to establish a direct relationship between human emotion and facial oxygenation. The strong emotion such as anger is found to stimulate more oxygen under facial skin transforming the face red or rosiness. Furthermore, other emotions assisted with less oxygen concentration create the skin pallor or whitish. Our results in perceiving the human emotions based on facial skin color may contribute towards the development of human aided virtual reality and game environment.

Design of Sliding Window Based Corner Detection Algorithm and Architecture for Image Mosaicing

A new Sliding Window Based Corner Detection Algorithm has been developed for image mosaicing. Using this algorithm, a new architecture suitable for VLSI implementation has also been designed. The proposed design incorporates a high degree of pipelining and parallelism and hence offers high throughputs. The color image mosaicing is achieved by first convolving an original image using a 3x3 sliding window followed by smoothening the image using median filters. The design has been coded in Verilog as per RTL coding guidelines. The algorithm has also been coded in Matlab in order to validate the hardware results. The Verilog design of the proposed architecture for image mosaicing has been implemented on Xilinx Spartan 6 xc6slx45-3fgg676 FPGA device. The design utilizes about 144,858 gates and the operating frequency is about 100 MHz. The design is capable of processing high resolution color pictures of sizes of up to 1600× 1200 pixels in real time.

MP22-03 MALLEABLE PHYSICAL MODELS OF RENAL MALIGNANCIES CONSTRUCTED FROM 3-D PRINTERS TO ALLOW SURGICAL RESECTION FOR INDIVIDUALIZED PRE-SURGICAL SIMULATION

INTRODUCTION AND OBJECTIVES: The goal of partial nephrectomy is to remove renal cell carcinoma completely and to preserve normal renal parenchyma maximally, which make surgeons predict anatomical status of the kidney from image like pre-operative twodimensional CT. Patient-specific three-dimensional (3D) printed model could be useful during operation. METHODS: Nine patients successfully underwent partial nephrectomy with complete excision of the suspicious renal cell carcinoma by open (N1⁄47) or robotic assisted laparoscopic (N1⁄42) approach. Volumetric CT examinations were performed to evaluate renal mass. Aview software (In-house software, Asan Medical Center, Seoul, South Korea) has been used to reformat the renal anatomy, renal mass and measure tumor volume. The virtual resection simulation followed an adequate safety margin with 5 mm distance away from the renal mass. 3D printed kidney model was fabricated with Objet 500 CONNEX3 3D printer (Stratasys CO, USA) with high quality color resolution and Any desired color can be obtained with mixture of the three base colors , translucent, cyan, magenta. With a clear and translucent resin the kidney model was constructed with different colors. RESULTS: The renal mass could be visualized and differentiated from blood vessels and renal collecting system in this model. (Figure) The mean tumor size was 2.2 cm, tumor volume, 7.65 cm, expected remained renal tissue volume 169 cm (94%) and the RENAL nephrometry score ranges 5e9. Mean ischemic time and mean operation time were 16 min and 190 min. 3D printed kidney has an advantage that it enables them to obtain an incision line and depth of dissection. Additionally, it could measure tumor volume, expected resected renal tissue volume and predict remain renal parenchymal volume after operation. So these model could useful for predict renal function after nephrectomy. When we explain the operation procedure with 3D printed kidney model to patients, satisfaction of patients was increased and their concern was decreased. CONCLUSIONS: The use of the simulated patient-specific 3D printed kidney model facilitates the surgical procedure, due to enhancement of preoperative planning and intraoperative orientation of risk structure and target tissue, and may improve surgical outcome. Source of Funding: none

MP22-02 APPLICATION OF SIMULATED PATIENT-SPECIFIC 3D PRINTED KIDNEY MODEL FABRICATED BY COLOR MULTI-MATERIAL 3D PRINTER FROM VOLUMETRIC CT TO AID PARTIAL NEPHRECTOMY

You have accessJournal of UrologyTechnology & Instruments: Surgical Education & Skills Assessment I1 Apr 2015MP22-02 APPLICATION OF SIMULATED PATIENT-SPECIFIC 3D PRINTED KIDNEY MODEL FABRICATED BY COLOR MULTI-MATERIAL 3D PRINTER FROM VOLUMETRIC CT TO AID PARTIAL NEPHRECTOMY Yoon Soo Kyung, Namkug Kim, Dalsan You, Jeong In Gab, Jun Hyuk Hong, Choung-Soo Kim, Myungchan Park, Chanwoo Lee, and Sangjun Yoo Yoon Soo KyungYoon Soo Kyung More articles by this author , Namkug KimNamkug Kim More articles by this author , Dalsan YouDalsan You More articles by this author , Jeong In GabJeong In Gab More articles by this author , Jun Hyuk HongJun Hyuk Hong More articles by this author , Choung-Soo KimChoung-Soo Kim More articles by this author , Myungchan ParkMyungchan Park More articles by this author , Chanwoo LeeChanwoo Lee More articles by this author , and Sangjun YooSangjun Yoo More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1014AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The goal of partial nephrectomy is to remove renal cell carcinoma completely and to preserve normal renal parenchyma maximally, which make surgeons predict anatomical status of the kidney from image like pre-operative two-dimensional CT. Patient-specific three-dimensional (3D) printed model could be useful during operation. METHODS Nine patients successfully underwent partial nephrectomy with complete excision of the suspicious renal cell carcinoma by open (N=7) or robotic assisted laparoscopic (N=2) approach. Volumetric CT examinations were performed to evaluate renal mass. A-view software (In-house software, Asan Medical Center, Seoul, South Korea) has been used to reformat the renal anatomy, renal mass and measure tumor volume. The virtual resection simulation followed an adequate safety margin with 5 mm distance away from the renal mass. 3D printed kidney model was fabricated with Objet 500 CONNEX3 3D printer (Stratasys CO, USA) with high quality color resolution and Any desired color can be obtained with mixture of the three base colors □ translucent, cyan, magenta. With a clear and translucent resin the kidney model was constructed with different colors. RESULTS The renal mass could be visualized and differentiated from blood vessels and renal collecting system in this model. (Figure) The mean tumor size was 2.2 cm, tumor volume, 7.65 cm3, expected remained renal tissue volume 169 cm3 (94%) and the RENAL nephrometry score ranges 5–9. Mean ischemic time and mean operation time were 16 min and 190 min. 3D printed kidney has an advantage that it enables them to obtain an incision line and depth of dissection. Additionally, it could measure tumor volume, expected resected renal tissue volume and predict remain renal parenchymal volume after operation. So these model could useful for predict renal function after nephrectomy. When we explain the operation procedure with 3D printed kidney model to patients, satisfaction of patients was increased and their concern was decreased. CONCLUSIONS The use of the simulated patient-specific 3D printed kidney model facilitates the surgical procedure, due to enhancement of preoperative planning and intraoperative orientation of risk structure and target tissue, and may improve surgical outcome. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e241 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Yoon Soo Kyung More articles by this author Namkug Kim More articles by this author Dalsan You More articles by this author Jeong In Gab More articles by this author Jun Hyuk Hong More articles by this author Choung-Soo Kim More articles by this author Myungchan Park More articles by this author Chanwoo Lee More articles by this author Sangjun Yoo More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

ROAD AND ROADSIDE FEATURE EXTRACTION USING IMAGERY AND LIDAR DATA FOR TRANSPORTATION OPERATION

Abstract. Transportation agencies require up-to-date, reliable, and feasibly acquired information on road geometry and features within proximity to the roads as input for evaluating and prioritizing new or improvement road projects. The information needed for a robust evaluation of road projects includes road centerline, width, and extent together with the average grade, cross-sections, and obstructions near the travelled way. Remote sensing is equipped with a large collection of data and well-established tools for acquiring the information and extracting aforementioned various road features at various levels and scopes. Even with many remote sensing data and methods available for road extraction, transportation operation requires more than the centerlines. Acquiring information that is spatially coherent at the operational level for the entire road system is challenging and needs multiple data sources to be integrated. In the presented study, we established a framework that used data from multiple sources, including one-foot resolution color infrared orthophotos, airborne LiDAR point clouds, and existing spatially non-accurate ancillary road networks. We were able to extract 90.25% of a total of 23.6 miles of road networks together with estimated road width, average grade along the road, and cross sections at specified intervals. Also, we have extracted buildings and vegetation within a predetermined proximity to the extracted road extent. 90.6% of 107 existing buildings were correctly identified with 31% false detection rate.

PHOTOGRAMMETRIC PROCESSING USING ZY-3 SATELLITE IMAGERY

Abstract. This paper evaluates the stereoscopic capacities of the Chinese sensor ZiYuan-3 (ZY-3) for the generation of photogrammetric products. The satellite was launched on January 9, 2012 and carries three high-resolution panchromatic cameras viewing in forward (22º), nadir (0º) and backward direction (-22º) and an infrared multi-spectral scanner (IRMSS), which is slightly looking forward (6º). The ground sampling distance (GSD) is 2.1m for the nadir image, 3.5m for the two oblique stereo images and 5.8m for the multispectral image. The evaluated ZY-3 imagery consists of a full set of threefold-stereo and a multi-spectral image covering an area of ca. 50km x 50km north-west of Barcelona, Spain. The complete photogrammetric processing chain was executed including image orientation, the generation of a digital surface model (DSM), radiometric image correction, pansharpening, orthoimage generation and digital stereo plotting. All 4 images are oriented by estimating affine transformation parameters between observed and nominal RPC (rational polynomial coefficients) image positions of 17 ground control points (GCP) and a subsequent calculation of refined RPC. From 10 independent check points RMS errors of 2.2m, 2.0m and 2.7m in X, Y and H are obtained. Subsequently, a DSM of 5m grid spacing is generated fully automatically. A comparison with the Lidar data results in an overall DSM accuracy of approximately 3m. In moderate and flat terrain higher accuracies in the order of 2.5m and better are achieved. In a next step orthoimages from the high resolution nadir image and the multispectral image are generated using the refined RPC geometry and the DSM. After radiometric corrections a fused high resolution colour orthoimage with 2.1m pixel size is created using an adaptive HSL method. The pansharpen process is performed after the individual geocorrection due to the different viewing angles between the two images. In a detailed analysis of the colour orthoimage artifacts are detected covering an area of 4691ha, corresponding to less than 2% of the imaged area. Most of the artifacts are caused by clouds (4614ha). A minor part (77ha) is affected by colour patch, stripping or blooming effects. For the final qualitative analysis on the usability of the ZY-3 imagery for stereo plotting purposes stereo combinations of the nadir and an oblique image are discarded, mainly due to the different pixel size, which produces difficulties in the stereoscopic vision and poor accuracy in positioning and measuring. With the two oblique images a level of detail equivalent to 1:25.000 scale is achieved for transport network, hydrography, vegetation and elements to model the terrain as break lines. For settlement, including buildings and other constructions a lower level of detail is achieved equivalent to 1:50.000 scale.

Sonological Evaluation of Scrotal Pathology by High Resolution Ultrasound and Color Doppler

Introduction: The development of sonogram with high frequency linear transducer and color doppler is an important mile stone in evaluating scrotal pathologies. Computed tomography exposes testicles to the radiation and MRI is not so easily available. Therefore ultrasound with color Doppler is the best suited modality for the evaluation of scrotal pathologies as it is simple, noninvasive, reproducible, relatively inexpensive and widely available investigation that will not expose the testis to radiation. Aims and Objectives: To classify (etiologically) and to evaluate various scrotal pathologies using ultrasonography and describe the role of High resolution ultrasound and colour doppler in their diagnosis and differentiation. Materials and Methods: The study was done on 60 patients who were referred to the radiology department by the General Surgery and Urology departments for scrotal ultrasound and Doppler study. This study was conducted between May 2012 to September 2014 at Katuri Medical College and Hospital, Chinnakondrupadu, Guntur. Results : Of the 60 patients studied, incidence of various pathologies were as follows -inflammatory pathology in 26%, congenital in 12%, scrotal hernia in 16%, infertility in 8%, torsion in 7%, tumors in 3.3%, trauma in 3%, and others in 26.7%. The imaging features of these conditions with differentiating hallmarks are described. Conclusion: High frequency ultrasonography is invaluable in demonstrating normalcy of testes and epididymis in the presence of large hydroceles. High-frequency ultrasonography enables clear demonstration of the morphological alterations associated with acute scrotal inflammatory diseases. Color doppler sonography is highly sensitive in diagnosing acute scrotal pathology and accurately differentiates testicular ischemia /torsion from acute inflammatory conditions.

Importance of ultrasonography and colour doppler in evaluation of bowel pathology in clinically suspected cases.

Background: High resolution ultrasonography and colour doppler have become valuable diagnostic modalities for the evaluation of bowel pathology. Study was done to evaluate importance of ultrasound with colour doppler in bowel pathology arising from duodenum to rectum. Materials and Methods: A prospective study of 160 patients was done with bowel pathology during July 2013 to December 2014. The study group consists of patients who presented with clinical signs and symptoms pertaining to pathology arising from the duodenum, small bowel, large bowel and appendages. Detailed history was taken before the sonography examination. Results: In our study, out of 160 patients of bowel lesions, 42 patients (26.2%) were under 32 to 40 years age group. Pain in abdomen was the commonest presentation found in 149 patients (93.1%). Infection and Inflammatory lesions were the commonest bowel pathology detected in 109 patients (68.1%), among them appendicitis & its complication was the commonest pathology followed by abdominal tuberculosis. Neoplasm was 2nd most common pathology which constituted 28 patients (17.5%). The commonest malignant lesion was adenocarcinoma diagnosed in 19 patients (70%). Conclusion: Ultrasonography (USG) is the primary investigation of choice in the patients with pain in abdomen. The use of endosongraphy proved to be essential in detecting and staging rectosigmoid malignancy. Hydrocolon technique and fluid aided sonography also helped in delineating colonic masses. High frequency graded compression sonography proved to be essential in case with acute appendicitis.

Precise localization of eye centers in low resolution color images

The localization of eye centers and tracking of gaze constitutes an integral component of many human–computer interaction applications. A number of constraints including intrusiveness, mobility, robustness and high-price of eye tracking systems have hindered the way of the integration of eye trackers in everyday applications. Several ‘passive’ systems based on a single camera have been lately proposed in the literature, exhibiting though subordinate precision compared to the commercial, hardware-based eye tracking devices. In this paper we introduce an automatic, non-intrusive method for precise eye center localization in low resolution images, acquired from single low-cost cameras. To this end, the proposed system uses color information to derive a novel eye map that emphasizes the iris area and a radial symmetry transform which operates both on the original eye images and the eye map. The performance of the proposed method is extensively evaluated on four publicly available databases containing low resolution images and videos. Experimental results demonstrate great accuracy in challenging cases and resilience to pose and illumination variations, achieving significant improvement over existing methods.

Subjective Sensation of Color Differences – Determination of Thresholds Depending on Color Tones and Resolution

Abstract Colors are frequently defined by three points on the L*a*b* coordinates of the CIELAB color space, and the distance between two colors can be expressed as the total color difference ΔE. In particular with respect to reproducibility of print media color differences are an important parameter, as well as for car finishes and textile dyes. Color changes are also the result of ageing and weathering which is an issue for art objects and in the building and restoration sector. However, the subjective perceptibility of color differences depends on numerous factors and general thresholds are difficult to define. This study aimed therefore on defining tolerance levels for color changes in dependence of color tones and color tone combinations as well as their resolution. In total 30 test persons evaluated samples, which had been painted with acrylic artist colors with defined color differences (ΔE = 0–7). The test subjects realized color differences already at ΔE = 1–4 for the highest resolution. Threshold values have been identified for different tones as well as the effect of interdependencies between tones and the level of color heterogeneity between adjacent areas.

Volumetric display based on multiple mini-projectors and a rotating screen

A method has been proposed to realize a transparent volumetric display using multiple mini-projectors and a rotating screen. Correct two-dimensional cross-sectional images are projected on a bidirectional scattering projection screen, which rotates to form a three-dimensional (3-D) image due to human vision persistence. An illumination subsystem is designed to ensure the accurate synchronization between the projectors and the rotating screen. Therefore, low-speed and low-cost miniature display devices can be used in the mini-projectors to realize dynamic volumetric imaging, which can satisfy all criteria of real 3-D vision with full color and high resolution. Experimental results of volumetric imaging realized by this method are also presented.