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Objectives: The aim of the study was to analyze discomfort glare sensation in subjects aged 50 years and more in comparison with younger subjects (i.e. younger than 35 years of age). Material and Methods: The experiments were performed on a computer workstation placed in controlled lighting environment where 2 discomfort glare conditions were modeled. Each participant performed for about 1 h specially designed visual tasks, including the tests with Landolt's rings presented on the screen by a computer program. The glare evaluation method consisted of subjective evaluation of discomfort glare on the semantic glare rating scale, tests of mesopic contrast and glare sensitivity, subjective assessment of lighting quality and asthenopic symptoms. The time needed to perform the task and the number of mistakes were also recorded. The subjective evaluation of glare was compared with the Unified Glare Rating (UGR) index calculated by the DIALux simulation program. Results: A higher percentage of the younger group subjects assessed glare after the experimental session as uncomfortable and intolerable than in the 50+ group, who more often assessed glare as acceptable. The assessment of discomfort glare in the younger group corresponded to higher UGR value compared to UGR value calculated by DIALux. In the 50+ group, such correlation was found only for lower discomfort glare (UGR = 19). The results showed that younger participants more frequently suffered from visual fatigue and assessed lighting as less comfortable. However, the mesopic glare sensitivity increased significantly after the experiments only in the 50+ group under both glare conditions. Conclusions: The obtained results showed that discomfort glare sensation changes with age. The younger population seems to be more sensitive and demanding than the older one in relation to discomfort glare limiting, in spite of the lack of significant objective measures of fatigue. The exposure of the elderly to bigger discomfort glare could adversely affect the objective measures of fatigue like mesopic glare sensitivity and visual performance.

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A comparison of methods for determining unified glare rating was performed. An analysis was made based on the results of experiments carried out for a typical office workstation under a controlled lighting environment. The DIALux simulation software and the LMK measuring system were used to calculate the unified glare rating. The main aim of the research was to verify the correctness of these two methods through a subjective glare assessment made by a group of 65 people. A comparison of the unified glare rating values determined by the different objective techniques with the subjective estimation shows that the LMK measurement is the more accurate method.

The problem of multimodal interaction is discussed. The use of blinking and winking, interpreted as Beye gestures,^is considered. The main aim of this study is to propose a simple method that allows the recognition of the state of the eye: open or closed; and to distinguish between blinking and winking. Wearable technology has been used in the introduced solution. Placing the camera close to the eye allows us to simplify the complicated image analysis. The proposed method works irrespective of the user's location and his/her gaze direction. Further, the use of infrared radiation limits the influence of external disturbing factors such as lighting conditions and pollution. The new solution is tested in two types of experiments: with 2 × 5000 pictures of open and closed eyes and with a group of 30 participants. The total correctness of the eye state recognition is 99.68% (99.94% for open eyes and 99.42% for closed ones). This result implies that the proposed solution can be effectively applied to real-world scenarios. Two applications are considered. In the first one, blinking recognition allows us to check whether safety glasses are used appropriately. In the second application, the control of mouse keys is replaced with eye gestures interpreted from a winking analysis. The introduced solution allows for effective and correct eye state recognition. The new method of control by eye gestures was accepted by the participants of this study.

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