Embedded Files
2025
2025
2 June 2025: We welcomed Ms. Greta Horvathova, a PhD student from Imperial College London, as an international exchange student. She will be staying in our lab for three months, during which she will take part in psychophysical experiments related to color. Although her stay is short, we hope she will have meaningful interactions with our students. As this is her first visit to Japan, we hope she enjoys her time here to the fullest! In addition, third-year undergraduate students Okawa-kun and Fujiyama-kun have been provisionally assigned to our Laboratory. We look forward to working with them!
24 May 2025: Several conference presentations are scheduled for June. First, at the Annual Meeting of the Color Science Association of Japan, which will be held at Yamagata University’s Yonezawa Campus, Son-san (Ph.D. student) and A/Prof Nagai will each give oral presentations. Son-san will present the content of a paper currently under preparation for submission, while A/Prof Nagai will present a combined study that includes work by Koizumi-san, who graduated last school year, and Miyoshi-kun, a second-year master’s student. Presentation practice will begin shortly.
Minwoo Son, Takehiro Nagai: Comparison of simple reaction times across color directions right after a sudden decrease in background luminance
Takehiro Nagai, Kana Koizumi, Kenta Miyoshi: Enhancing perceived skin lightness through facial feature manipulation – when viewing a face only briefly.
1 Apr 2025: A new academic year begins today—it’s hard to believe how quickly time flies. We’re excited to welcome three new members to our team: Hatao-kun and Miura-san both first-year master’s students (M1), as well as Zhu-san, who joins us as a graduate research student. With these new additions, we look forward to seeing a fresh atmosphere take shape. We appreciate your continued support throughout the year!
26 March 2025: Two master's course students, Okamoto-san and Sato-san have completed their studies at Science Tokyo as of today's graduation ceremony. Both of them joined our Lab from the master's program, and although their styles were different, they each made steady progress in their research and ultimately achieved outstanding results. Beyond that, they both contributed significantly to creating a positive vibe in the lab. I’m truly grateful to have had them as part of our team. I wish them all the best in their future endeavors! Also, an undergraduate student, Koizumi-san, completed her undergraduate thesis in a short period of time. From next year, she will begin her master’s research in another lab. Meanwhile, the two remaining M2 students, Nakajima-kun and Hanada-kun, will be continuing on to the doctoral program in our lab. Especially, Nakajima-kun was recognized for his research achievements and received the Outstanding Student Award (Master's) in our department. I’m looking forward to seeing their continued success. It’s truly been a wonderful year working with such an amazing team. Great job, everyone, and thank you for all your hard work!
13 March 2025: Li-san, a doctoral student, has had his paper published in Journal of the Optical Society of America A. His research highlights, from the perspective of attentional mechanisms, that the criteria used to judge the magnitude of color differences qualitatively differ depending on whether the differences are small or large.
Kashi Li, & Takehiro Nagai: Attention plays a greater role in judging large color differences than small ones. Journal of the Optical Society of America A, 42(5), B353-B364, 2025. (Published article, Open Access).
19 February 2025: Our collaborative research with Prof. Juno Kim from UNSW Australia in 2023 has been published in PLOS ONE. This study demonstrates that the perception of translucency can be significantly influenced by the order in which stimulus images are presented during psychological experiments. Additionally, we found that binocular disparity, motion, and specular highlights play crucial roles in maintaining a stable perception of translucency. The findings highlight key considerations for translucency perception research. Please take a look if you are interested. Coincidentally, from February 17, B4 student Watanabe-kun and I (Nagai) are visiting Prof. Juno Kim’s lab to conduct follow-up experiments. I will return after one week, but Watanabe-kun will be staying for four weeks, which should be a great learning experience for him.
Takehiro Nagai, Hiroaki Kiyokawa, & Juno Kim: Top-down effects on translucency perception in relation to shape cues. PLOS ONE, 20(2):e0314439, 2025. (Published article, Open Access).
7 February 2025: Two papers by PhD student Duay have been published. Congratulations! The first paper proposes a method for color calibration of head-mounted displays (HMDs), and then the second paper demonstrates how this method enables the use of HMDs in color vision research, particularly in studies on color constancy. As the importance of investigating perceptual characteristics in realistic environments continues to grow, this research is expected to contribute significantly to that direction.
Killian Duay, Yoko Mizokami, & Takehiro Nagai: VR HMD color calibration and accurate control of emitted light using Three.js. Journal of Vision, 25(2):4, 2025. (Published article, Open Access).
Killian Duay, & Takehiro Nagai: Impact of field of view on color constancy in virtual reality. Journal of the Optical Society of America A, 42(5), B199-B213, 2025. (Postprint) (Published article, Subscription required)
24 January 2025: From January 22 to 24, the 2025 Winter Meeting of the Vision Society of Japan was held at Kogakuin University, where many students from Nagai Lab presented their research. Among them, M2 student Nakajima-kun won the Best Presentation Award! Congratulations to him! I would also like to extend our gratitude to all the other participants for their hard work and dedication. Meanwhile, the next challenge awaits: the Master's Thesis Presentation and Undergraduate Thesis Presentation are just around the corner.
2024
2024
11 December 2024: On December 11, our Ph.D. student Killian and four M1 students presented posters at our department's Research Plan Presentation. Based on evaluations by the professors, Oda-kun and Miyoshi-kun were honored with the Outstanding Presentation Award. Congratulations!
3 December 2024: Two B3 students, Onodera-kun and Tomoeda-kun, have been assigned to our lab. We look forward to working with you!
1 November 2024: Miyoshi-kun (M1) will be presenting his research on the illusory effects related to perceived facial brightness at the Human Information Research Group, Institute of Image Information and Television Engineers. He’s currently hard at work preparing for the presentation!
1 October 2024: Our university's name has changed from Tokyo Institute of Technology to Institute of Science Tokyo. Our laboratory will continue its activities as usual, and we appreciate your ongoing support.
18 September 2024: Sato-san (M2) presented her research on the impact of tone mapping, widely used in psychophysical studies of material perception, on glossiness evaluation at the summer meeting of the Vision Society of Japan. Starting tomorrow, we will begin a seminar camp focused on an in-depth reading of papers on vision science. The camp schedule includes 1.5 days of seminars, followed by 1.5 days of leisure activities.
31 July 2024: Son-san (a Ph.D. candidate)'s research has been published online as an Early View in Color Research and Application. The study demonstrates that when the background luminance changes abruptly, such as in abruptly changing light environments, not only luminance discrimination sensitivity but also color discrimination sensitivity changes.
Minwoo Son, & Takehiro Nagai: Luminance and chromaticity discrimination sensitivities right after an abrupt decrease in background luminance. Color Research and Application, Early View Online, 2024 (link to the article)
19 June 2024: The research by Li-san, a Ph.D. candidate in our lab, has been published in Scientific Reports. His study demonstrated that when judging color differences, as the stimulus color differences become more pronounced, the strategy for judgment shifts from quantitative assessment of color differences to categorical judgments. This finding provides important insights into the characteristics of 'color differences' and the role of categories in color perception. In conjunction with this publication, A/Prof. Nagai presented his findings at Symposium on color vision and facial skin color, organized by Prof. Mizokami from Chiba University. Notably, this research continues from Ito-kun's master's thesis at Yamagata University, establishing a connection from Yamagata University to TokyoTech.
Kashi Li, & Takehiro Nagai: Increasing magnitude of color differences amplifies category effects. Scientific Reports, 14, 13665, 2024 (link to the article).
6 June 2024: Koizumi-san, a third-year undergraduate student, has been newly assigned to our laboratory. Joining midway through the academic year might be a bit challenging, but we encourage Koizumi-san to gradually acclimate to this new environment.
22 May 2024: As the themes for our new members have been decided, our research is becoming more active. In June and July, we will present our research both inside and outside TokyoTech. Now, it's time to organize our data and practice our presentations!
Research plan presentation, Dept. Information and Communications Engineering, TokoTech Information and Communication
M1 students Wang-san and Jiang-san will each present a poster.
Symposium on Color Vision and Facial Skin Color @ Chiba University
Takehiro Nagai (invited): "Color Appearance Influenced by Color Experiences"
55th Annual Conference of the Color Science Association of Japan [Fukuoka] '24
Ikuto Hanada, Takehiro Nagai: "Color features involved in color preferences of abstract paintings – an analysis using machine learning"
Yuna Okamoto, Takehiro Nagai: "Impact of spectral distributions of lighting on background colors and color constancy"
Nagi Kinoshita, Masahiro Suzuki, Osamu Masuda, Keiji Uchikawa, Takehiro Nagai: "Hue dependence in the contribution of ipRGC to brightness perception"
Takehiro Nagai, Suzuha Horiuchi: "The transformation of perceived colors due to color discrimination experiences"
The 16th Asia Pacific Conference on Vision @ Singapore
Kenta Nakajima, Takehiro Nagai: "The impact of temporal attitudes on physical and affective material impressions – an analysis using EEG"
Li Kashi, Takehiro Nagai: "Removing attention deteriorates the judgment of large color differences"
26 April 2024: We had a welcome party at our campus in conjunction with the Kaneko Laboratory. I talked with many of the students, and everyone seemed energetic and great! In addition, a research paper by Horiuchi-san, who completed her master's program at the end of the last fiscal year, has been finally published in Scientific Reports. It presents intriguing results regarding color perception, showing that color appearance changes by repeatedly discriminating specific colors over a short period. The results are very interesting in understanding the formation of our color vision.
Suzuha Horiuchi, & Takehiro Nagai: Color discrimination repetition distorts color representations. Scientific Reports, 14, 9615, 2024. (https://doi.org/10.1038/s41598-024-60283-4)
5 April 2024: With the start of the new fiscal year, we're delighted to extend a warm welcome to Mr. Killian Duay (a doctoral student) and to Mr. Oda and Mr. Kawahara (master's course students) as new members. Anticipation is high for a fresh atmosphere. We look forward to working with the new students!
27 March 2024: Six M2 students successfully completed their master’s program. Despite the challenges posed by the remote guidance provided by A/Prof Nagai, everyone achieved commendable results. In addition, we are pleased to announce that Horiuchi-san has been honored with the Outstanding Student Award (Master’s course) in our department. To all our M2 students, we extend our warmest congratulations! As you transition into your professional careers, we wish you continued success!
2023
2023
4 December 2023: We are pleased to welcome Mr. Ishiguro and Mr. Watanabe, who are third-year undergraduate students, to the Nagai Lab as new student members. We hope they will enjoy their time here.
14 October 2023: Son-san (D), Takanashi-san (M2), and Horiuchi-san (M2) gave presentations at Optica Fall Vision Meeting held in Seattle, USA, from October 6 to 8. They seemed nervous, but they did great! I hope it was a good experience for them. I also made new connections with some attendees and learned about cutting-edge research on color vision. I am now back in Australia and apologize for any inconvenience my absence may have caused.
Suzuha Horiuchi, Takehiro Nagai: Spillover effects of color discrimination training on color category boundaries and color appearance
Minwoo Son, Takehiro Nagai: Luminance and chromaticity discrimination sensitivities following a sudden decrease in background luminance
Mizuki Takanashi, Takehiro Nagai: Image features involved in translucency enhancement by chromaticity information
3 October 2023: We have had some changes in our members. First, Mr. Chen, a research student, transferred to another university, and Mr. Wang became a new M1 student. Also, we welcomed Mr. Jiang as a new M1 student. Mr. Chen, we wish you all the best in your new environment. Mr. Wang and Mr. Jiang, we look forward to working with you!
20 September 2023: Li-san, Son-san, Nakajima-kun, and A/Prof. Nagai presented our research at the Summer Meeting of the Vision Society of Japan. Son-san won the Best Presentation Award! Congratulations!! I was sorry that Morishita-kun could not join us because of his health condition, though. I appreciate everyone’s efforts! Here are the titles of our presentations:
Yoshinori Morishita, Ichiro Kuriki, Takehiro Nagai: Investigation of color vision characteristics reflected in steady-state visual evoked potentials
Kenta Nakajima, Takehiro Nagai: An attempt to discriminate surface quality perception and affective impressions arising from object images based on EEG.
Minwoo Son, Takehiro Nagai: Luminance and chromaticity discrimination characteristics when background luminance decreases abruptly
Kashi Li, Takehiro Nagai: The effect of color categories on color difference perception of various sizes
Takehiro Nagai, Ikuto Hanada: The relationship between the rarity of color distribution in visual environment and color preference in abstract paintings
31 August 2023: A/Prof Nagai has returned to Japan for a short time! Today, Aso-kun (a second-year master’s student) gave a presentation at the annual conference of the Institute of Image Information and Television Engineers. He did a great job, thanks to multiple practices in the lab! Well done, Aso-kun. Other students will present our research at more academic conferences, including the Vision Society of Japan’s Summer Meeting in Tokushima in September and the Optica Fall Vision Meeting in Seattle, USA, in October.
Takemichi Aso, Miyu Kunieda, Takehiro Nagai: Observation conditions and image features suitable for computer displays with low-luminance reproduction
25 June 2023: M1 student Hanada-kun made a presentation at the Annual Meeting of the Color Science Association of Japan held on June 24th and 25th. We are delighted to announce that he received the Outstanding Presentation Award. Congratulations!
17 May 2023: A/Prof. Nagai will be away until approximately March 20, 2024, as he is staying in Australia. During his time there, he will be residing with A/Prof. Juno Kim at the University of New South Wales. They plan to conduct collaborative research focusing on the integration of virtual reality (VR) and material perception. We apologize in advance for any inconvenience this may cause.
3 April 2023: A new academic year has begun, and we are pleased to welcome new members to our team: M1 students Okamoto-san and Sato-san, as well as research student Wang-san. Our total number of students is now 16. We are excited for another productive year and kindly ask for your continued support.
27 March 2023: M2 students, Koizumi-kun and Nohira-kun graduated at the degree conferral ceremony held today. In addition, Koizumi-kun received the Outstanding Master's Student Award from our department for his master's research. The graduation of these two students is deeply moving as they have supported various aspects of our laboratory's activities. We're excited to see what they'll accomplish in their future careers. The resources that they've left behind will be used to further develop our lab. Congratulations on your graduation!
4 March 2023: Nohira-kun's (M2) study has been published in Journal of Vision. It is known that we rely on object surface regions other than the specular highlights when judging object lightness. We investigated the complexity of image processing involved in excluding highlights using an image feature set called PS statistics. Additionally, a paper co-authored with Yuyang Cai and Professor Juno Kim from UNSW has been published in JOSA A. This research reveals the relationship between highlight and object color perception in translucent objects. Congratulations on these achievements!
Nohira, H., & Nagai, T. (2023). Texture statistics involved in specular highlight exclusion for object lightness perception. Journal of Vision, 23(3):1. (https://doi.org/10.1167/jov.23.3.1)
Cai, Y., Kiyokawa, H., Nagai, T., Haghzare, L., Arnison, M., & Kim, J. (2023). Effects of specular roughness on the perception of color and opacity. Journal of the Optical Society of America A, 40(3), A220-A229. (https://doi.org/10.1364/JOSAA.479972)
16 Feb 2023: Three M2 students and two B4 students gave presentations about their master's and undergraduate thesis. Despite being busy with thesis writing and preparations since January, they all gave excellent presentations. Well done! The three M2 students will be graduating soon.
19 Jan 2023: A study by Koizumi-kun (M2) has been published in Journal of Vision. He showed that 1) perceived glossiness increases when objects are colored, and 2) the dominating factor of this color-induced glossiness enhancement is the Helmholtz-Kohlrausch effect (the effect that chromatic colors make images appear brighter) under different conditions. Congratulations!
Koizumi, K., & Nagai, T. (2023). The dominating impacts of Helmholtz-Kohlrausch effect on color-induced glossiness enhancement. Journal of Vision, 23(1):11. (https://doi.org/10.1167/jov.23.1.11)
2022
2022
13 Dec 2022: Horiuchi-san (M1) received the Best Presentation Award at the research plan presentation held on December 2. Congratulations!
5 Dec 2022: Two new undergraduate students have just joined our team. Welcome, Kinoshita-kun and Miyoshi-kun!
29 Nov 2022 Koizumi-kun (M2) gave a presentation at a meeting of Human Information research group of The Institute of Image Information and Television Engineers. As a result, he received the Best Presentation Award! Congratulations!
3 Nov 2022: A paper on translucency perception by Dr. Kiyokawa, a former student and postdoc in Nagai Lab, has been published in Vision Research (https://doi.org/10.1016/j.visres.2022.108140). This study shows the possibility that translucency perception relies on luminance orientation information of object images related to shapes of diffuse and specular reflection components. This study was conducted under the supervision of Dr. Juno Kim from UNSW.
Hiroaki Kiyokawa, Takehiro Nagai, Yasuki Yamauchi, & Juno Kim: The perception of translucency from surface gloss. Vision Research (in press). https://doi.org/10.1016/j.visres.2022.108140
29 June 2022: The research of Kukuta-san, who completed her master's program at Yamagata University (FY2020), has been published in Journal of Vision. In this study, she analyzed the properties of color aftereffects and elucidated higher-order color representations in the visual cortex.
Takehiro Nagai, Kana Kakuta, & Yasuki Yamauchi: Luminance dependency of perceived color shift after color contrast adaptation caused by higher-order color channels. Journal of Vision, 22(7):8, 2022. https://doi.org/10.1167/jov.22.7.8.
26 June 2022: Horiuchi-san (M1) gave a presentation at the annual conference of Color Science Association of Japan, and received the Presentation Encouragement Award. Congratulations!
1 April 2022: The new academic year has begun. Two doctoral students and four master's students have newly joined our laboratory. I'm looking forward to working together with the new members.
30 March 2022: Mr. Saeki, Mr. Taniguchi, Mr. Totsuka, and Mr. Makihira successfully completed their master's programs. Congratulations! I wish them all the best in their future careers.
3 March 2022: The study by Mr. Okada, who received a master's degree last year, has been published online as a regular paper in Vision Research. In this paper, we used a reverse correlation method in which local sub-band contrast was modulated to clarify image features contributing to facial skin lightness perception. The results showed that luminance contrast around the eyes has a strong impact on skin lightness perception.
Takehiro Nagai, Takuya Okada, Ken Nishino, & Natsuko Okiyama: Impact of local luminance contrast on face lightness perception: a psychophysical reverse correlation study using sub-band contrast modulation noise. Vision Research, 2022. https://doi.org/10.1016/j.visres.2022.108028.
2021
2021
2 December 2021: Two new undergraduate students, Nakajima-kun and Hanada-kun have joined our group. Welcome to Nagai Lab!
1 December 2021: Dr. Hiroaki Kiyokawa, who was a post-doc in our lab, is starting a new job as a post-doc in Dr. Ryusuke Hayashi's lab at AIST today. He was very helpful in giving various advice to the students. We look forward to Hiroaki's continued success and meeting again at future conferences!
22 November 2021: Kiyokawa-kun (post-doc) was awarded a prize for excellent presentation for his presentation at the autumn meeting of the Color Science Association of Japan, which was held on November 20. Congratulations!
12 August 2021: The study by Ms. Hayasaka, who received a master's degree from Yamagata Univ. in 2020, has been published online as a journal paper in Color Research and Application (https://doi.org/10.1002/col.22723). The study demonstrated that luminance contrast sensitivity (especially in the low spatial frequency ranges) is optimized for luminance distributions of the adaptation background. This study collaborates with Prof. Kuriki in Saitama University and Dr. Sato in Ichinoseki National College of Technology.
Misaki Hayasaka, Takehiro Nagai, Yasuki Yamauchi, Tomoharu Sato, & Ichiro Kuriki: Luminance contrast detection is optimized for the large-scale luminance texture of the surround. Color Research and Application, 2021 (early online) (link to the article)
22 July 2021: We had an online party to celebrate the end of job hunting of M2 members. Thank you, Aso-kun and Totsuka-kun, for organizing this event. We had fun and deepened our friendship. Unfortunately, most of the current students have never experienced offline social events in the lab. So I hope we can do something offline before they complete the master's course studies.
28 June 2021: Koizumi-kun (M1) presented his research at the annual conference of Color Science Associations of Japan on June 26. Thankfully, he received the Encouragement Presentation Award. Congratulations!
27 May 2021: Koizumi-kun and Nohira-kun (M1) gave poster presentations at Vision Sciences Society Annual Meeting (V-VSS 2021), which was held until yesterday. We hope we can participate in the international conferences on-site next time.
Kazuto Koizumi, Yuma Watanabe, & Takehiro Nagai: What factors determine the effects of color on perceived gloss? -Helmholtz-Kohlrausch effect vs highlight-shading color contrast-. Vision Sciences Society 2021 Annual Meeting, Online, May 24, 2021.
Hiroki Nohira, & Takehiro Nagai: Effects of the surface-undulation spatial frequency on perceptual highlight removal for lightness perception. Vision Sciences Society 2021 Annual Meeting, Online, May 24, 2021.
1 Apr 2021: A new academic year has started. Dr. Kiyokawa, who received his doctoral degree from Yamagata University this spring, has joined our group as a postdoctoral researcher (as JSPS PD research fellow ).
5 Feb 2021: The study by Kiyokawa-kun (D2, Yamagata Univ.) has been published in Frontiers in Psychology. We have reported the impact of high spatial frequency components of luminance on manipulations of perceived glossiness just by changing the sub-band contrast.
Hiroaki Kiyokawa, Tomonori Tashiro, Yasuki Yamauchi, & Takehiro Nagai: Spatial Frequency Effective for Increasing Perceived Glossiness by Contrast Enhancement. Frontiers in Psychology, 12:625135, 2021.
2020
2020
1 Apr 2020: Two master's course students, Taniguchi-kun and Totsuka-kun, joined our laboratory. Welcome to Nagai Laboratory!
17 Mar 2020: Our study (main contributor is Dr. Sato from National Institute of Technology Ichinoseki College) about spatial perception (collinear facilitation) based on chromatic signals and its relation to cortical hue representations has been published.
Tomoharu Sato, Takehiro Nagai, & Ichiro Kuriki: Hue selectivity of collinear facilitation. Journal of the Optical Society of America A, A154-A162, 2020. (link to publisher's website)
2019
2019
12 Dec 2019: English website opened.
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