The evolution of modern sensors for image acquisition brings as much obstacles as many possibilities to obtain multidimensional data with high resolution and rich information. One of the most perceptible destructive factors in visual data is noise. Due to complexity of modern sensors and approaches to signal collecting or preprocessing, noise model becomes complicated. The article’s goal is to introduce and solve a problem of suppressing additive spatially correlated noise (ASCN) which is present in images due to different sources and has various levels of correlation. It is shown that even modern filters attempting to suppress correlated noise often demonstrate unsatisfactory efficiency. Here we propose and analyze two modifications of 2D discrete cosine transform (DCT) based filter and the state-of-the-art BM3D technique. Both are based on accounting spatial spectrum of the noise by setting frequency-dependent thresholds. Furthermore, the modified BM3D filter exploits a similarity measure robust to noise spectrum in block matching.

This paper proposes the method of interaction design to present haptic experience as intended in virtual reality (VR). The method that we named “Augmented Cross-Modality” is to translate the physiological responses, knowledge and impression about the experience in real world into audio-visual stimuli and add them to the interaction in VR. In this study, as expressions for presenting a haptic experience of gripping an object strongly and lifting a heavy object, we design hand tremor, strong gripping and increasing heart rate in VR. The objective is, at first, to enhance a sense of strain of a body with these augmented cross-modal expressions and then, change the quality of the total haptic experience and as a result, make it closer to the experience of lifting a heavy object. This method is evaluated by several rating scales, interviews and force sensors attached to a VR controller. The result suggests that the expressions of this method enhancing a haptic experience of strong gripping in almost all participants and the effectiveness were confirmed.

Previous research has shown that head-mounted display users experience sickness symptoms. However, many studies have used contents with fast motion, which might mask more subtle effects caused by the head-mounted display properties, like optical design or head tracking. To investigate the symptoms caused by reasons other than fast motion in contents, we used 360-degree videos without fast motion components. In a between-subjects experiment, the participants viewed 360-degree videos for 5, 10, or 20 minutes with Samsung Gear head-mounted display. The Simulator Sickness Questionnaire (SSQ) results indicate that symptom levels started to rise between 10 and 20 minutes’ viewing time. The symptom profiles showed that disorientation symptoms dominated, followed by oculomotor and nausea symptoms. Cluster analysis revealed the presence of a high symptom group and a low symptom group in participants. In the former, the symptom levels increased with viewing time, while in the latter the symptoms remained mild. Based on the results, we can conclude that viewing time between 10 and 20 minutes is critical for the development of sickness symptoms for sensitive users.

Nonlinear complementary metal-oxide semiconductor (CMOS) image sensors (CISs), such as logarithmic (log) and linear–logarithmic (linlog) sensors, achieve high/wide dynamic ranges in single exposures at video frame rates. As with linear CISs, fixed pattern noise (FPN) correction and salt-and-pepper noise (SPN) filtering are required to achieve high image quality. This paper presents a method to generate digital integrated circuits, suitable for any monotonic nonlinear CIS, to correct FPN in hard real time. It also presents a method to generate digital integrated circuits, suitable for any monochromatic nonlinear CIS, to filter SPN in hard real time. The methods are validated by implementing and testing generated circuits using field-programmable gate array (FPGA) tools from both Xilinx and Altera. Generated circuits are shown to be efficient, in terms of logic elements, memory bits, and power consumption. Scalability of the methods to full high-definition (FHD) video processing is also demonstrated. In particular, FPN correction and SPN filtering of over 140 megapixels per second are feasible, in hard real time, irrespective of the degree of nonlinearity.

Flash photography has been widely used to study the droplet dynamics in drop-on-demand (DoD) inkjet due to its distinct advantages in cost and image quality. However, the whole setup, typically comprising the mounting platform, flash light source, inkjet system, CCD camera, magnification lens and pulse generator, still costs tens of thousands of dollars. To reduce the cost of visualization for DoD inkjet droplets, we proposed to replace the expensive professional pulse generator with a low-cost microcontroller board in the flash photographic system. The temporal accuracy of the microcontroller was measured by an oscilloscope. The microcontroller’s temporal stability was compared with a professional pulse generator by tracking a large number of droplet positions. To validate the effectiveness of the whole setup, the droplet ejection and the droplet impact on a silicon wafer were quantitatively analyzed and compared with theoretical predictions. Finally, sample images of droplet ejected from a commercial inkjet cartridge were presented to show the flexibility of the system.

Noninvasive diagnosis and treatment of disease, which can greatly reduce the pain of patients and improve the efficiency of diagnosis, is increasingly advocated in modern health care. Traditional endoscopy as an important clinical diagnostic tool can provide only rough information on the structure of the tissue. In order to obtain morphological information at the cellular level, biopsy is often required. However, biopsy brings suffering to the patient and is costly. In recent years, the confocal endoscopic imaging system has been developed, yet has not been widely applied owning to the small imaging field of view. In view of these problems, we designed an endoscopic microscopic imaging system based on the combination of macroscopic vision and microscopic resolution. Here, we describe the design principle of the system. We further demonstrate the feasibility of the system by performing automated cell counts in an in vivo subcutaneous cancer model.

Up to now, a number of tone mapping methods have been proposed through a lot of literatures to reduce halos and to overcome loss of detailed information in a given high dynamic range image (HDRI) while reproducing colors. In these efforts, there are a wide variety of tone mapping techniques including global tone mapping technique, local tone mapping technique, and a combination of both techniques. However, there are still unsolved challenges such as halos, loss of detailed information, and color distortion like luminance shift and hue shift in the consequence of performing the conventional tone mapping methods. Accordingly, this article presents a novel approach to solving these problems by combining the modified guided filter method and the Total Variation (TV)-based restoration model, thereby comprising the proposed tone mapping operator. The main purpose of combining both is to decompose the HDRI into the base layer (illumination components) and the detail layer (reflectance components), which offers several advantages: removing noise and representing detailed information in resulting images. Adaptive gamma correction is also adopted to effectively reduce luminance shift and hue shift by automatically controlling the dynamic range, parameter free. The chromatic adaptation transform is then used to address the mismatch between displayed images and real-life scenes based on the human visual perception (HVP). The main contribution of the proposed approach is to overcome halos and loss of detailed information arising from the local tone mapping technique or the global tone mapping one. The experimental results show that the proposed tone mapping method yields better performance over the conventional method in subjective and quantitative qualities and color reproduction.