Although the psychophysiological signs of fatigue are well known, automatic methods for the detection of fatigue in employees in specific working conditions are still lacking. Many people do repetitive work on computers and become fatigued; therefore, the detection of fatigue in employees can help prevent accidents and increase their work efficiency. In this paper, we propose an algorithm for the effective detection of fatigue which is based only on electrooculographic (EOG) signal. Three features were assessed: blink duration, blink amplitude, and time between blinks. To cause fatigue, the N-back test, lasting for 60 minutes, was carried out. The article presents the research results for 24 users. The effectiveness of the proposed system was measured by the accuracy of classification. The average classification accuracy was 0.93 for user-dependent mode and 0.89 for user-independent mode. The results of the conducted experiments indicated that assessing the three proposed features can help in the effective detection of fatigue in users.

Fast detection of skin colour in images is an important task for computer vision and image processing. In this study, a new thresholding method for detecting skin colour has been introduced. The proposed method uses CMYK colour space, which, although not popular in image processing, especially in skin detecting algorithm, turned out to be a good choice. Its properties seem the most appropriate for the task of skin colour detection. Some experiments have been worked out using Compaq Database – a large database of skin and non‐skin photos. A comparison of the new method against well‐known thresholding methods in RGB, YCbCr and HSV spaces were prepared. In this comparison, the proposed method in CMYK colour space wins. This good result was further improved using a simple cascade algorithm, where two spaces RGB and CMYK were used.

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). 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. 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. 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.

The problem of multimodal interaction is discussed. The use of blinking and winking, interpreted as “eye 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.

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.