First Demonstration of Calibrated Color Imaging by the CAOS Camera

The Coded Access Optical Sensor (CAOS) camera is a novel, single unit, full spectrum (UV to short-wave IR bands), linear, high dynamic range (HDR) camera. In this paper, calibrated color target imaging using the CAOS camera and a comparison to a commercial HDR CMOS camera is demonstrated for the first time. The first experiment using a calibrated color check chart indicates that although the CMOS sensor-based camera has an 87 dB manufacturer-specified HDR range, unrestricted usage of this CMOS camera’s output range greatly fails quality color recovery. On the other hand, the intrinsically linear full dynamic range operation CAOS camera color image recovery generally matches the restricted linear-mode commercial CMOS sensor-based camera recovery for the presented 39.5 dB non-HDR target that also matches the near 40 dB linear camera response function (CRF) range of the CMOS camera. Specifically, compared to the color checker chart manufacturer provided XYZ values for the calibrated target, percentage XYZ mean errors of 8.3% and 10.9% are achieved for the restricted linear range CMOS camera and CAOS camera, respectively. An alternate color camera assessment gives CIE ΔE00 mean values of 4.59 and 5.7 for the restricted linear range CMOS camera and CAOS camera, respectively. Unlike the CMOS camera lens optics and its photo-detection electronics, no special linear response optics and photo-detector designs were used for the experimental CAOS camera, nevertheless, a good and equivalent color recovery was achieved. Given the limited HDR linear range capabilities of a CMOS camera and the intrinsically wide linear HDR capability of a CAOS camera, a combined CAOS-CMOS mode of the CAOS smart camera is prudent and can empower HDR color imaging. Applications for such a hybrid camera includes still photography imaging, especially for quantitative imaging of biological samples, valuable artworks and archaeological artefacts that require authentic color data generation for reliable medical decisions as well as forgery preventing verifications.

Binocular summation is affected by crowding and tagging

In perceptual crowding, a letter easily recognized on its own, becomes unrecognizable if it is surrounded by other letters, an effect that confers a limit on the visual processing. Models assume that crowding is a hallmark of the periphery but that it is almost absent in the fovea. However, recently it was shown that crowding occurs in the fovea of people with an abnormal development of functional vision (amblyopia), when the stimulus is presented for a very short time. When targets and flankers are dissimilar, the crowding is reduced (tagging). Since a combination of binocular inputs increases the processing load, we investigated whether color tagging the target reduces crowding in the fovea of subjects with normal vision and determined how crowding is combined with binocular vision. The crowding effect at the fovea was significantly reduced by tagging with a color target. Interestingly, whereas binocular summation for a single letter was expected to be about 40%, it was significantly reduced and almost absent under crowding conditions. Our results are consistent with the notion that the crowding effect produces a high processing load on visual processing, which interferes with other processes such as binocular summation. We assume that the tagging effect in our experiment improved the subject's abilities (sensitivity and RT) by creating a "segmentation", i.e., a visual simulated separation between the target letter and the background. Interestingly, tagging the target with a distinct color can eliminate or reduce the crowding effect and consequently, binocular summation recovers.

Task-Irrelevant Features in Visual Working Memory Influence Covert Attention: Evidence from a Partial Report Task

Selecting a target based on a representation in visual working memory (VWM) affords biasing covert attention towards objects with memory-matching features. Recently, we showed that even task-irrelevant features of a VWM template bias attention. Specifically, when participants had to saccade to a cued shape, distractors sharing the cue’s search-irrelevant color captured the eyes. While a saccade always aims at one target location, multiple locations can be attended covertly. Here, we investigated whether covert attention is captured similarly as the eyes. In our partial report task, each trial started with a shape-defined search cue, followed by a fixation cross. Next, two colored shapes, each including a letter, appeared left and right from fixation, followed by masks. The letter inside that shape matching the preceding cue had to be reported. In Experiment 1, either target, distractor, both, or no object matched the cue’s irrelevant color. Target-letter reports were most frequent in target-match trials and least frequent in distractor-match trials. Irrelevant cue and target color never matched in Experiment 2. Still, participants reported the distractor more often to the target’s disadvantage, when cue and distractor color matched. Thus, irrelevant features of a VWM template can influence covert attention in an involuntarily object-based manner when searching for trial-wise varying targets.

RESEARCH OF DIGITAL CAMERA DYNAMIC RANGE ON THE IMAGING PROCESSING BASIS

Digital images provide to determine photometric and colorimetric properties of objects subject to validation all elements of a measuring channel (digital camera, software, display) and solve the problem of their limited dynamic ranges. The aim of the study was to explore the dynamic range of a digital camera for use in photometric and colorimetric measurements.The Laboratory of Photonics at the Institute of Microelectronics and Optoelectronics (Warsaw Technical University, Poland) conducted a comparative experiment to determine the threshold of sensitivity, linearity and range of application the digital camera. Color target sets with certified brightness and chromaticity were created at the terminals and recorded with a digital camera with different exposure times. The authors propose a method to extend the dynamic range of a digital camera for red, green and blue color channel of intensities by pairing the calibration dependencies, and determine the true brightness and color of a point on the object by calculation.Calibration dependencies (triads) of digital camera for red, green and blue color channels intensities were constructed. These dependences allow determining lower and upper bounds of the dynamic range. Each triad has a form of the hysteresis loop. The experiment showed that the accuracy of this method is ± 3–5 %.

The Speed of Serial Attention Shifts in Visual Search: Evidence from the N2pc Component

Finding target objects among distractors in visual search display is often assumed to be based on sequential movements of attention between different objects. However, the speed of such serial attention shifts is still under dispute. We employed a search task that encouraged the successive allocation of attention to two target objects in the same search display and measured N2pc components to determine how fast attention moved between these objects. Each display contained one digit in a known color (fixed-color target) and another digit whose color changed unpredictably across trials (variable-color target) together with two gray distractor digits. Participants' task was to find the fixed-color digit and compare its numerical value with that of the variable-color digit. N2pc components to fixed-color targets preceded N2pc components to variable-color digits, demonstrating that these two targets were indeed selected in a fixed serial order. The N2pc to variable-color digits emerged approximately 60 msec after the N2pc to fixed-color digits, which shows that attention can be reallocated very rapidly between different target objects in the visual field. When search display durations were increased, thereby relaxing the temporal demands on serial selection, the two N2pc components to fixed-color and variable-color targets were elicited within 90 msec of each other. Results demonstrate that sequential shifts of attention between different target locations can operate very rapidly at speeds that are in line with the assumptions of serial selection models of visual search.

Target Tracking Based on Improved Camshift and Kalman Filter

A tracking algorithm based on improved Camshift and Kalman filter is proposed in this paper to deal with the problems in traditional Camshift algorithm, such as tracking failure under color interference or occlusion. Firstly, the proposed algorithm improves the single color target model and presents a novel target model, which fuses color and motion cues, to enhance the robustness and accuracy of target tracking. And in order to increase the tracking efficiency, the algorithm combines Kalman filter with the improved Camshift algorithm by using Kalman filter to predict the position of the tracking target under color noises and occlusion. The experiment results demonstrate that the proposed algorithm can track the target object accurately and has better robustness.

Influence Analysis of Color Input Target to the Scanner Color Characteristic

Scanner is the indispensable image acquisition equipment in the prepress system, high quality ICC profile is significant to reflect the color expression of scanner, and the character of ICC profile is influenced in a great extent by the color input target. The subject is to set up the ICC profile by scanning and data processing Kodak IT8.7/2, Goldencolor GCT 3.0 and GretagMacbeth ColorChecker SG, get the influence of each color input target to the scanner color characteristic through the accuracy analysis and color gamut comparison. Research shows that three kinds of color target has its own advantage, Kodak IT8.7/2 has big color gamut, high accuracy, and better reappearance ability, meets the needs of the everyday users; GretagMacbeth ColorChecker SG is good to the reappearance of high saturate manuscript, and its precision is high, applying to recreate natural landscape; Glodencolor GCT 3.0 is of high precision and larger color gamut, but its expression ability is not good enough in the section of high saturation red and magenta, it can produce high quality scanner ICC profile also. Consequently, it should be taken into consideration of the manuscript, color gamut, accuracy and cost-effective factors comprehensively when choosing scanner color target, eventually you get a satisfactory scanning result.