Method

culated based on the reference resolving power of the eyes. Meaning that the human eye with 20/20 vision can detect or resolve details as small as 1/60th of a degree of arc. This distance represents the point beyond which some details in the picture are no longer able to be resolved, so pixels begin to blend. Closer to the screen than this may result in the need for a higher resolution display. This value should be lowered if visual acuity is worse than 20/20, raised if visual acuity is better.

Figure 5.11 Section of the room and field of view

Participants. The test participants for steps 1 and 2 were group members and colleagues from Aalborg University Copenhagen, students at the MSc in Lighting Design, and external participant. Eight individuals participated in the test consisting of 3 males and 5 females. All participants were aged 23–30 years. Participants were from different nationalities, living in Denmark. A pilot test was conducted the previous week of the test, consisting of 3 group members as participants. The participants were asked about their age, gender, visual problems, and a colour blindness test was taken before they participated in the test.

Location. The test was conducted in a 16 square meters room (Figure 5.12), which had 3 windows that faced southwest, blocked out to prevent the daylight from coming through to keep the light levels of the room uniform, creating a controlled environment. The purpose of this is to maintain the room dark enough to make the only source of light the one produced by the screen, allowing participants to use mesopic vision. The wall where the TV screen was located on a yellow wall, with a reflectance of 37%. A luminance meter with the brand Konica Minolta model LS-150 was used to record luminance levels in the areas of interest.

Procedure

Before the test, the subjects were asked to take the “Ishihara test” for colour blindness by Colorite (Colorlite Ltd., 2021), the results were recorded. During the test, each of the subjects entered the room previously described and sat on a chair. At his point, the subject was not asked to do

Figure 5.12 Axonometry of the room with the position of the subject

Figure 5.13 1. Example slide step 1 (3000K - 3420K) 2. Example slide test 2 (3000K-2730K) anything but wait in the darkness for 15 minutes for visual adaptation to the low light levels. Once the dark adaptation procedure was completed, the subject was asked to stand facing the TV screen on a mark on the floor at exactly 1.80 meters in front of it to start the test. The test consisted of 2 steps, both with equal dynamic, except for the display of the images. In the first step, 30 different slides were presented. In each slide, there were two rectangles parallel to each other with the measurement 35 cm by 15 cm, with a separation of 5 cm, on a black (RGB 0, 0, 0) background. The colour value of the right-side rectangle was fixed to the value of CCT 3000K (RGB 255, 168, 85) constantly throughout the test. The left-side square changed randomly its CCT value on higher and lower figures, between fixed values (Figure 5.13, picture 1). Three slides presented 3000K in both rectangles. The data collected from the participants consisted of two spreadsheets, one for each of the steps, containing the answers from the participants in a table.

Each slide was visible to the subject for 2 seconds and between slides, the black background was visible for 5 seconds to avoid comparison with the previous slide. The subject was asked to rank the colour discrimination according to 1. Same colour: no perception on the variation, 2. Little difference: slightly variation, 3. Big difference: very noticeable variation. (Figure 5.14)

For the second step, the same procedure previously described was used, varying the images presented. The slides consisted of a black background containing a square of 35 cm by 35 cm, presenting 5 horizontal sections,

1 2