DOI: 10.5281/zenodo.4394535
title: LUTCHI Colour Appearance Data - Luo and Rhodes (1997)

description: <strong>Source URL</strong>: https://web.archive.org/web/20040212195937/http://colour.derby.ac.uk:80/colour/info/lutchi/ <strong>M. Ronnier Luo and Peter A. Rhodes</strong> Colour & Imaging Institute<br> University of Derby<br> Derby, UK Contents Introduction Table I: Summary of the experimental groups Data file description Table IIa: Summary of the data files and viewing conditions used in each phase Table IIb: Normalised tristimulus values (Xo, Yo, Zo) for each phase References Downloading Instructions An agreement was reached between members of the consortium to make the data available in May 1997. The data can be publicly accessed from the Internet web site of the Colour & Imaging Institute (formerly known as the Design Research Centre), University of Derby at http://colour.derby.ac.uk/. Researchers or industrialists are welcome to acquire this data set for further study. We hope that more models will be derived or refined with the availability of this data set. <strong>Introduction</strong> The LUTCHI data is a large set of psychophysical experimental data for describing colour appearance. The main body of the results was obtained from two consecutive research projects funded by the British Government's Alvey (1987-1989) and IEAPT (1990-1992) programmes. These results have previously been published in Color Research and Application [1][2][3][4]. The project consortium were: LUTCHI, Crosfield Electronics (now Fuji Film Electronic Imaging, FFEI), Coats Viyella and Sigmex Displays Ltd (now MISYS). The data were produced at the Loughborough University of Technology Computer-Human Interface Research Centre and are hence named the LUTCHI colour appearance data. Subsequently, two new data sets were also accumulated: Kuo & Luo [5], and BIT [6]. These data sets were also included to form the full LUTCHI Colour Appearance Data Set. The data were used to test various colour appearance models [2], to refine the Hunt colour appearance model [7][8] and to derive the LLAB colour appearance model [9][10]. Most importantly, this data set together with the others were used for the development of the CIE colour appearance model, CIECAM97S [11][12]. The experiments were conducted using a magnitude estimation method1 under various conditions of illumination. The data are divided into eight groups according to the experimental viewing conditions summarised in Table I. They are mainly categorised by the media used: reflective (R), self-luminous (Monitor), 35mm projection (35mm), large cut-sheet transparency (LT) and BIT. The latter group was complied by the Beijing Institute of Technology, China to investigate colour appearance under mesopic region with an isolated viewing field. It was treated as an independent group. For data in the reflective group, they are further divided into four subgroups: high luminance (HL), low luminance (LL), various luminance (VL) and textile samples (textile). In total, there are fifty-nine different phases. Each phase represents a set of distinct experimental conditions. A number of colours were assessed by a panel of four to eight normal colour vision observers in each phase. Each colour was scaled in terms of its lightness, colourfulness and hue attributes. In addition, the brightness attribute was used in the R-VL group. (There are twelve phases in the R-VL group. The lightness, colourfulness and hue, and brightness, colourfulness and hue results were obtained for the first and last six phases respectively.) <strong>Table I: Summary of the experimental groups</strong> <pre><code class="language-markdown">| Data group | No. of phases | Description of each data group | Reference no. | |---------------|---------------|---------------------------------------------------------------|---------------| | R-HL | 6 | Reflective media with luminances ranging 364-232 cd/m2 | 1 | | R-LL | 6 | Reflective media with luminances ranging 44-41 cd/m2 | 1 | | R-VL | 12 | Reflective media with luminances ranging 843-0.4 cd/m2 | 2 | | R-textile | 3 | Large textile samples with luminances ranging 730-340 cd/m2 | 4 | | Self-luminous | 11 | Monitor colours with luminances ranging 45-20 cd/m2 | 1 | | 35mm | 6 | 35mm transparency with luminances ranging 113-45 cd/m2 | 3 | | LT | 10 | Cut-sheet transparency with luminances ranging 2100-320 cd/m2 | 3 | | BIT | 5 | Isolated viewing field with luminances ranging 90-3.6 cd/m2 | 5 |</code></pre> <strong>Data File Description</strong> Table IIa summarises the data files and viewing conditions used in each experimental phase. Each phase includes two data files: visual and colorimetric. The data in the visual file have been arranged into four columns: the sample number, mean visual results of the lightness or brightness, colourfulness and hue. The arithmetic mean was used for calculating lightness (0 for black, 100 for white) and hue (0 for red, 100 for yellow, 200 for green, 300 for blue and 400 for red) results, the geometric mean for brightness (0 for black) and colourfulness (0 for neutral colours) results in open ended scales. The data in the colorimetric file have been arranged into three columns: x, y and Y, which were measured using a telespectroradiometer (TSR). The sequence of experimental samples is the same for both the visual and colorimetric files. The other parameters are: the number of samples used in the phase, the start and end numbers of the neutral samples, the scaling factor of the Y values used for adjusting those in the colorimetric file, the Y value of the background and the luminance of the reference white sample. The illuminant used in each phase is given in Table IIb described using the Xo Yo and Zo tristimulus values. The visual results for the neutral samples have no hue and a colourfulness of zero. In the visual data file, they are not consistently expressed. Users need to realise this before attempting to use these samples. The hue results of the neutral colours should not be used to test or derive colour appearance models. The Y value of the background has already been scaled. Luminance, in cd/m<sup>2</sup> units, was measured against the reference white by the TSR under a particular phase. All colourfulness results are in the same visual scale except those of the R-textile and BIT data. For testing colour models' performance, there is a need to obtain a suitable scaling factor to adjust each model's chroma or colourfulness predictions to make them have the same scale as the visual results. <strong>Table IIa: Summary of the data files and viewing conditions used in each phase</strong> <pre><code class="language-markdown">| Group | Phase | File Name | | No. of Samples | Neutrals | | Scaling Factor | Y of Background | Luminance (cd/m2) | |-----------|-------|--------------|--------------|----------------|----------|-----|----------------|-----------------|-------------------| | | | Visual | Colorimetric | | Start | End | | | | | R-HL | 1 | nlmean.wh | cold50wnl | 105 | 41 | 46 | 0.88 | 100 | 264 | | | 2 | nlmean.bh | cold50gb | 105 | 41 | 46 | 0.84 | 6.2 | 252 | | | 3 | nlmean.gh | cold50gb | 105 | 41 | 46 | 0.84 | 21.5 | 252 | | | 4 | nld65.gh | cold65 | 105 | 41 | 46 | 0.81 | 21.5 | 243 | | | 5 | nlwf.gh | colwf | 105 | 41 | 46 | 0.84 | 21.5 | 252 | | | 6 | nla.gh | colah | 105 | 41 | 46 | 0.84 | 21.5 | 232 | | R-LL | 1 | nlmean.wl | cold50wnl | 105 | 41 | 46 | 0.88 | 100 | 44 | | | 2 | nlmean.bl | cold50gb | 105 | 41 | 46 | 0.84 | 6.2 | 42 | | | 3 | nlmean.gl | cold50gb | 105 | 41 | 46 | 0.84 | 21.5 | 42 | | | 4 | nld65.gl | cold65 | 105 | 41 | 46 | 0.81 | 21.5 | 40.5 | | | 5 | nlwf.gl | colwf | 105 | 41 | 46 | 0.84 | 21.5 | 42 | | | 6 | nla.gl | colal | 105 | 41 | 46 | 0.84 | 21.4 | 42 | | R-VL | 1 | mean4.p1 | col.rf.p1 | 40 | 37 | 40 | 1 | 21.5 | 843 | | | 2 | mean4.p2 | col.rf.p2 | 40 | 37 | 40 | 1 | 21.5 | 200 | | | 3 | mean4.p3 | col.rf.p3 | 40 | 37 | 40 | 1 | 21.5 | 62 | | | 4 | mean4.p4 | col.rf.p4 | 40 | 37 | 40 | 1 | 21.5 | 17 | | | 5 | mean4.p5 | col.rf.p5 | 40 | 37 | 40 | 1 | 21.5 | 6 | | | 6 | mean4.p6 | col.rf.p6 | 40 | 37 | 40 | 1 | 21.5 | 0.4 | | | 7 | mean4.p7 | col.rf.p1 | 40 | 37 | 40 | 1 | 21.5 | 843 | | | 8 | mean4.p8 | col.rf.p2 | 40 | 37 | 40 | 1 | 21.5 | 200 | | | 9 | mean4.p9 | col.rf.p3 | 40 | 37 | 40 | 1 | 21.5 | 62 | | | 10 | mean4.p10 | col.rf.p4 | 40 | 37 | 40 | 1 | 21.5 | 17 | | | 11 | mean4.p11 | col.rf.p5 | 40 | 37 | 40 | 1 | 21.5 | 6 | | | 12 | mean4.p12 | col.rf.p6 | 40 | 37 | 40 | 1 | 21.5 | 0.4 | | R-textile | 1 | kuo.d65.vis | kuo.d65.col | 240 | 1 | 12 | 0.74 | 16 | 250 | | | 2 | kuo.tl84.vis | kuo.tl84.col | 239 | 1 | 10 | 0.74 | 16 | 540 | | | 3 | kuo.a.vis | kuo.a.col | 239 | 1 | 11 | 0.74 | 16 | 250 | | CRT | 1 | lmean.ww | cold50wl | 94 | 39 | 44 | 0.89 | 100 | 40 | | | 2 | lmean.bb | cold50gbl | 100 | 39 | 44 | 0.89 | 5 | 44.5 | | | 3 | lmean.gg | cold50gbl | 100 | 39 | 44 | 0.89 | 20 | 44.5 | | | 4 | lmean.gw | cold50gbl | 100 | 39 | 44 | 0.89 | 20 | 44.5 | | | 5 | lmean.gb | cold50gbl | 100 | 39 | 44 | 0.89 | 20 | 44.5 | | | 6 | ld65.gg | cold65.l | 103 | 39 | 44 | 0.81 | 21.5 | 40.5 | | | 7 | ld65.gw | cold65.l | 103 | 39 | 44 | 0.81 | 21.5 | 40.5 | | | 8 | lwf.gg | colwf.l | 103 | 39 | 44 | 0.84 | 21.5 | 28.4 | | | 9 | lwf.gw | colwf.l | 103 | 39 | 44 | 0.84 | 21.5 | 28.4 | | | 10 | la.gg | cola.l | 61 | 29 | 34 | 0.84 | 21.5 | 20.3 | | | 11 | la.gw | cola.l | 61 | 29 | 34 | 0.84 | 21.5 | 20.3 | | 35mm | 1 | mean.35.p1 | col.35.p1 | 99 | 93 | 99 | 1 | 15.6 | 75 | | | 2 | mean.35.p2 | col.35.p2 | 99 | 93 | 98 | 1 | 14.7 | 75 | | | 3 | mean.35.p3 | col.35.p3 | 99 | 93 | 99 | 1 | 18.9 | 113 | | | 4 | mean.35.p4 | col.35.p1 | 99 | 93 | 99 | 1 | 18.9 | 45 | | | 5 | mean.35.p5 | col.35.p5 | 95 | 89 | 95 | 1 | 19.2 | 47 | | | 6 | mean.35.p6 | col.35.p6 | 36 | 26 | 30 | 1 | 18.9 | 113 | | LT | 1 | mean.p1 | col.p1 | 98 | 94 | 98 | 1 | 15.9 | 2259 | | | 2 | mean.p2 | col.p2 | 98 | 94 | 98 | 1 | 17.1 | 689 | | | 3 | mean.p3 | col.p3 | 98 | 94 | 98 | 1 | 16.9 | 325 | | | 4 | mean.p4 | col.p4 | 98 | 94 | 98 | 1 | 17.4 | 670 | | | 5 | mean.p5t | col.p5t | 97 | 93 | 97 | 1 | 9.6 | 1954 | | | 6 | mean.p6t | col.p6t | 94 | 90 | 94 | 1 | 9.5 | 619 | | | 7 | mean.p7t | col.p7t | 93 | 89 | 93 | 1 | 9.8 | 319 | | | 8 | mean.p8 | col.p8 | 98 | 94 | 98 | 1 | 9.4 | 642 | | | 9 | mean.p10 | col.p10 | 98 | 94 | 98 | 1 | 9.6 | 658 | | | 10 | mean.p1t | col.p1t | 94 | 90 | 94 | 1 | 17.5 | 680 | | BIT | 1 | BIT.p1.vis | BIT.p1.col | 120 | 1 | 16 | 1 | 0.6 | 90 | | | 2 | BIT.p2.vis | BIT.p2.col | 120 | 1 | 18 | 1 | 0.6 | 3.6 | | | 3 | BIT.p3.vis | BIT.p3.col | 120 | 1 | 15 | 1 | 0.6 | 90 | | | 4 | BIT.p4.vis | BIT.p4.col | 90 | 1 | 18 | 1 | 0.6 | 90 | | | 5 | BIT.p5.vis | BIT.p5.col | 90 | 1 | 12 | 1 | 0.6 | 3.6 |</code></pre> <strong>Table IIb: Normalised tristimulus values (Xo Yo Zo) for each phase</strong> <pre><code class="language-markdown">| Group | Phase | File Name | | No. of Samples | Xo | Yo | Zo | |-----------|-------|--------------|--------------|----------------|--------|-----|--------| | | | Visual | Colorimetric | | | | | | R-HL | 1 | nlmean.wh | cold50wnl | 105 | 97.13 | 100 | 76.62 | | | 2 | nlmean.bh | cold50gb | 105 | 97.09 | 100 | 83.1 | | | 3 | nlmean.gh | cold50gb | 105 | 97.09 | 100 | 83.1 | | | 4 | nld65.gh </code></pre>