In this field study, a series of psychophysical tests were conducted to investigate the impact of indoor lighting on students’ visual perception and cognitive performance. A typical classroom of Wuhan University (China) was fitted with tubular light-emitting diode (LED) sources and LED panel sources in two experiments, respectively. Under the two lighting environments, seventy-nine college students were invited to complete a group of visual tests, which included colour preference evaluations of fruit and vegetables and skin tone, perceptual judgement on the atmosphere of the lighting environment, a reading comfort assessment concerning different paper colours, a Karolinska Sleepiness Scale (KSS) test quantifying alertness, and the Anfimov test of attention (also concerning paper colours). These tests were conducted twice, before and after a two-hour self-study under each lighting environment, with the aim of investigating the impact of visual fatigue on visual perception and cognitive performance. It was found that the influence of indoor lighting was significant on skin preference and atmosphere perception, while no measured effects of lighting were observed on participant’s alertness and attention. Meanwhile, the impact of visual fatigue was also found to be insignificant in this case. Interestingly, paper colour, rather than indoor lighting, was found to have a significant impact on the visual comfort of text reading. In addition, degree of proficiency significantly influenced the proofreading speed and accuracy of the subjects the in Anfimov test, which we believe should be taken into consideration when implementing similar tests in follow-up studies. The preliminary findings of this field study should provide a deeper understanding of how changes in classroom lighting contribute to visual perception and cognitive performance of occupants.

In the digital printing process, reliable colour reproduction is commonly achieved by printer characterisation, which defines the correspondence between the input device control values and the output colour information. The cellular Yule–Nielsen spectral Neugebauer model, together with its variants, is widely adopted in this topic because of its superb colorimetric and spectral accuracy. However, it seems that current studies have neglected an inconspicuous defect in such models when characterising printers equipped with black ink. That is, the cellular structure of these models overemphasises the sampling for dark-tone colours, and thus leads to relatively large errors in light tones. In this paper, taking a CMYK printer as an example, a simple and effective solution is proposed with no need of extra sampling. With the aid of a newly built cellular spectral Neugebauer model for the embedded CMY printer, this approach optimises the printer characterisation for light tones, slightly improves the precision for middle tones while it maintains the accuracy for dark tones. The performance of the proposed method was evaluated with regard to three different kinds of substrates and the experimental results validated its improvement in spectral printer characterisation.