Hyeon-Jeong Suk

User-preferred color temperature adjustment for smartphone display under varying illuminants

Abstract. The study aims to investigate the user-preferred color temperature adjustment for smartphone displays by observing the effect of the illuminant’s chromaticity and intensity on the optimal white points preferred by users. For visual examination, subjects evaluated 14 display stimuli presented on the Samsung Galaxy S3 under 19 ambient illuminants. The display stimuli were composed of 14 nuanced whites varying in color temperature from 2900 to 18,900 K. The illuminant conditions varied with combinations of color temperature (2600 to 20,100 K) and illuminance level (30 to 3100 lx) that simulated daily lighting experiences. The subjects were asked to assess the optimal level of the display color temperatures based on their mental representation of the ideal white point. The study observed a positive correlation between the illuminant color temperatures and the optimal display color temperatures (r=0.89, p<0.05). However, the range of the color temperature of the smartphone display was much narrower than that of the illuminants. Based on the assessments by 100 subjects, a regression formula was derived to predict the adjustment of user-preferred color temperature under changing illuminant chromaticity. The formula is as follows: [Display Tcp=6534.75 log (Illuminant Tcp)−16304.68 (R2=0.87, p<0.05)]. Moreover, supporting previous studies on color reproduction, the effect of illuminant chromaticity was relatively weaker under lower illuminance. The results of this experiment could be used as a theoretical basis for designers and manufacturers to adjust user-preferred color temperature for smartphone displays under various illuminant conditions.

Context-based presets for lighting setup in residential space

This study aims to derive context-based lighting setup presets in residential space by exploring the multilateral relationships among household activities, affects, and lighting setups. Three procedures were involved: First, sixty affective words were evaluated through which seven affect factors were extracted to facilitate the evaluation of colored illumination in the subsequent experiment. Second, in the user study, seven affect factors and thirty household activities were used to evaluate 147 lighting setups extracted from combinations of twelve hues, six illuminance levels, and three purity levels. As a result, twenty lighting setup presets were derived that were not only activity-based, but affect-based as well. Lastly, the twenty presets were prototyped as a set of testbed to further explore potentials and limitations. This study demonstrates that intuitive, context-based presets can help users explore the effects of colored illumination in creating a diverse range of user experiences.

Adaptive luminance contrast for enhancing reading performance and visual comfort on smartphone displays

Abstract. This study developed a model for setting the adaptive luminance contrast between text and background for enhancing reading performance and visual comfort on smartphone displays. The study was carried out in two experiments. In Experiment I, a user test was conducted to identify the optimal luminance contrast with regard to subjects’ reading performance, measured by lines of text reading and visual comfort, assessed by self-report after the reading. Based on the empirical results of the test, an ideal adaptive model which decreases the luminance contrast gradually with passage of time was developed. In Experiment II, a validation test involving reading performance, visual comfort, and physiological stress measured by a brainwave analysis using an electroencephalogram confirmed that the proposed adaptive luminance contrast is adequate for prolonged text reading on smartphone displays. The developed model enhances both reading performance and visual comfort as well as reduces the energy consumption of a smartphone; hence, it is expected that this study will be applied to diverse kinds of visual display terminals.

Investigation of eye-catching colors using eye tracking

An eye tracking experiment was conducted to investigate the relationship between eye gazing movements and the color attributes to support the creation of effective communication and increase aesthetic satisfaction. With consideration to the context of smart phones, the study focused on icon arrays, and thus each stimulus set was composed of 25 color square patches arrayed in the format of a 5 by 5 grid. The experiment was divided into three parts, each examining one specific attribute of color, while controlling its other attributes. Fifteen college students were recruited, among whom all partook in all three parts. In Part I, hue difference was examined. Each stimulus set contained 25 hues under a fixed tone. It was revealed that subjects were more attentive to warm colors than to cool colors, particularly when warm colors were arranged along the horizontal and vertical axes; In Part II, the experiment dealt with tone difference. 25 tone variations for red, green and blue were provided as stimulus sets. However, the result indicated that changes in tone does not have a significant influence on subjects’ initial attention; Lastly, in Part III, combinations of colors were examined to determine whether color contrast influenced participants’ attention in a manner different from that of single colors. Among them, icons with complementary contrast gained the greatest attention. Throughout the experiments, the background was applied with either black or white; however a contrast effect between background and foreground was not noticeable.

Do curved displays make for a more pleasant experience

This study investigated the benefits of a curved display compared to a flat display and proposed the optimal radius of curvature for a monitor. The study was carried out in two steps. For identifying the optimal radius, a bendable monitor prototype was used to enable subjects to adjust the display radius manually. Each subject was instructed to search for an optimal radius according to individual preference and visual comfort. Six different themes were applied for the display content. The subjects also reported the radius in which a visual distortion occurred. As a result, it was found that curvature with a radius equal to 600 mm to 700 mm is optimal for a 23-inch diagonal display, while 700 mm to 800 mm is appropriate for a 27-inch diagonal display. Moreover, when the radius of curvature was smaller than 600 mm, a majority reported distortion regardless of the display size. Next, a validation test confirmed that the subjects read the texts faster on the curved display than on the flat display. Based on the empirical results of two experiments, the excellence of a curved monitor in terms of visual comfort, preference, and immersion was verified.

The Emotional Characteristics of White for Applications of Product Color Design

This study investigates the emotional characteristics of various shades of white. In Experiment I, the emotional characteristics of 13 basic colors were evaluated based on four factors—flamboyant, elegant, clear, and soft—and white was identified to be dominantly elegant. In Experiment II, the emotional characteristics of whites were assessed to derive an equation for predicting the emotional quality. In Experiment III, 1:1 scale mock-ups of mobile phones, coated with various shades of white as well as different levels of gloss and texture, were employed for the further emotional assessment in real-life situations. Consistent tendencies were observed in the experiments, confirming the validity of the results. In addition, although color was the most dominant element in deciding product emotion, gloss, and texture were also influential elements. This study provides empirical evidence of the emotional responses to different shades of white and can help designers find an appropriate color for designing white-based products.

A color scenario of Eco & Healthy Driving for the RGB LED based interface display of a climate control device

The study demonstrates a process of synergizing both exploratory and confirmatory research approaches to design the color for a luminescent surface facilitated by RGB LEDs. Focusing on the relationship between color and in-door climate of automobiles, the study consists of three parts: In Part I, a workshop of ten designers was executed in which ideas were exploited to find in-car scenarios. The scenarios were evaluated based on the criteria of interesting, informative, and inspiring aspects to conclusively derive the scenario labeled “Eco & Healthy Driving” In Part II, a user test was carried out to investigate the relationship between the attributes of luminescent color-hue, brightness, and purity- and an indoor climate condition. In the user test (n= 36), subjects were instructed to match a luminescent color to a given in-car climate condition. The user test results revealed that hue category of luminescent surface is related to temperature while brightness of luminescent color is correlated with blow level; Lastly, in Part III, by employing the results of user test, a guideline for implementing the new design scenario, “Eco & Healthy Driving” was projected for further development and application.

Altruistic interaction design: a new interaction design approach for making people care more about others

The importance of design ethics in HCI has gained increasing attention the last several years. In this research, we propose a new concept of interaction that restructures its conventional notion. It is expected that this new concept will increase social empathy among people, which will eventually result in more positive ethical behaviors. This new structure of interaction breaks the current closed interaction cycle that focuses on a complete input-output feedback loop. Instead, it makes the cycle imperfect so that people cannot experience it without seeking help from others or being helped by the same. We call this concept altruistic interaction design and designed a case, the Altruistic Fan, as an applied product example. This paper explains the concept of altruistic interaction design and its application process to a real product. The study closes with the results of an exploratory user study utilizing an altruistic interaction design product (Altruistic Fan).

Designing skin-dragging haptic motions for wearables

Skin-dragging is an emerging type of haptic feedback that coveys both precise spatial and temporal tactile cues through the motion of a small pin dragged across the skin. While past research focused on building skin-dragging wearable devices with different form-factors, and testing their feasibility, it is still unclear what the users perception of such haptic stimuli is, and how designers should generate dragging motion-patterns for informative feedback to be presented on a finger. In this work, we attempt to answer these questions. We therefore asked designers to create dragging motions using changes of speed, direction and length. We then tested the generated skin-dragging motions with a haptic smart-ring, classified them and extracted guidelines that can be used to convey rich and informative feedback on the fingers.

Key Color Generation for Affective Multimedia Production: An Initial Method and Its Application

In this paper, we introduce a method that generates a key color to construct an aesthetic and affective harmony with visual content. Given an image and an affective term, our method creates a key color by combining a dominant hue of the image and a unique tone associated with the affective word. To match each affective term with a specific tone, we collected color themes from a crowd-sourced database and identified the most popular tone of color themes that are relevant to each affective term. The results of a user test showed that the method generates satisfactory key colors as much as designers do. Finally, as a prospective application, we employed our method to a promotional video editing prototype. Our method automatically generates a key color based on a frame of an input video and apply the color to a shape that delivers a promotional message. A second user study verifies that the video editing prototype with our method can effectively deliver the desired affective state with a satisfactory quality.