Visual Comfort of Tablet Devices under a Wide Range of Ambient Light Levels
Round 1
Reviewer 1 Report
According to my opinion to study ambient illumination 15000 lx is not frequently used (in rooms where special visual tasks are performed, the lighting ranges from 3,000 to 10,000 lx), because this ambient value is too high and does not represent standard ambient (in working, living environment etc.). The wider scale of ambient of illumination in the interval from 150 lx to 1500 lx (which were presented in the previous study of authors - lines 19, 20) would be more appropriate on this evaluation, with the combination of the interaction between polarity, ambient illumination, illumination contrast and chromatic contrast, the latter of which are often be the variables of primary interest. Based on the next results will be possible to investigate the influence of ambient lighting conditions to improved the visual comfort for e-reading more exactly.
Author Response
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Author Response.pdf
Reviewer 2 Report
The article Visual Comfort of Tablet Devices under a Wide Range of Ambient Light Levels has 17 pages and is suitably divided into 6 chapters: introduction, methods, results, model, discussion, conclusions. It reads well, is very well prepared in terms of form and content, brings a lot of news.
I can mention the following to the submitted contribution: In recent years, tablet devices have become more and more common in people's daily lives. People use tablets for work, entertainment and communication. The authors propose an evaluation model based on ambient lighting, screen parameters and a visual estimate that considers the optimal viewing conditions when reading on the tablet display. The research builds on the authors' previous work, which examined how ambient lighting conditions, including CCT variations, lighting levels, and a combination of text and background brightness, affected the visual comfort of observers in electronic reading.
This study was designed based on this previous work to determine the visual comfort of tablet devices in extremely intense ambient light (i.e., 15,000 lx).
Based on experimental results and previous work, an evaluation model was developed to predict visual comfort. I have some observations about the work:
Line 52 ... 200 to 500 cd / m2 ...? ... see line 126 there it is OK.
Twenty-four observers aged 20 to 25 participate in the experiment. It seems that 24 observers is not a sufficient statistical sample to evaluate the results! Due to the experiment procedure, where a total of 15,120 ratings were collected (210 pairs in random order × 3 light levels × 24 observers). So that's enough.
In Table 2, Lightness (L *) has no dimension?
In Figure 4 (a) 150 lx vs. 1500 lx, (b) 150 lx vs. 1500 lx, (a) and (b) have the same conditions?
The authors refer appropriately to their previous work. The submitted work is of good quality, it has only a few minor shortcomings, I recommend publishing the article in the journal Applied Sciences.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The article Visual Comfort of Tablet Devices under a Wide Range of Ambient Light Levels is well structured, although there are some aspects that need to be improved and some corrections and/or observations that the authors should consider in order to improve the article:
Authors should clarify these aspects.
I find logical and I agree with the authors of this article that the greater the ambient lighting, greater will be the feeling of comfort for the use of electronic devices but due to the studies on the non-visual effects of light of the last decades I believe that it is necessary to change the way of description of the ambient light specifying the difference between the daylighting and led lighting in its composition. The advancement in LED lighting technology has also resulted in a large difference between the luminaires in their spectral composition. The authors of this study must specify the spectral composition and potency in each part of the spectrum of ambient lighting.
L 18-19: Human observers compare the visual comfort of pairs of different text-background lightness combinations on a tablet device under three ambient light levels (i.e., 150, 1500, and 15000 lx).
Reference whether or not there is daylighting in the experiments and the lighting spectral composition (irradiance (w/m2 nm per blue, green and red) of the luminaries that the eyes receive, not relative power. IRC and CCT are not sufficient yet.
I think it is necessary to work with irradiance (ambient light irradiance together with electronic device irradiance) measured at the level of the eyes.
All the experiments were done at the same daytime (in the morning, in the noon or in the afternoon) of the day?
L 45-46: ambient illuminance of 200 lx; L49-50: 200 and 500 lx; L59-60: ambient illumination higher than 700 lx…
What is the spectral composition of environmental light? Daylighting and indoor led lighting? Only indoor led lighting? What kind of indoor led lighting? The spectral power distribution is completely different in each case therefore non-visual responses (NIF) of the light that influence sensations.
L 112-114: Twenty-four observers aging from 20 to 25 years old.
Specify if there is any kind of refractive problem.
L 163: Under each illuminance level
Table 2 is about luminance, not illuminance.
L 333-334: Twenty-four observers evaluate the visual comfort by pair comparisons under the 150 lx, 1500 lx, and 15000 lx illuminance levels with a horizontal CCT of 6500 K.
Luminance or illuminace? It has been measured at the levels of the eyes?
How has been measured the illuminance? It has been measured with a radiometer or spectroradiometer? Which one (model technical characteristics)?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
I accept it in present form
