Reflection measurement and visual evaluation of the luminosity of skin coated with powder foundation

Reflection Measurement and VisualEvaluation of the Luminosity of SkinCoated with Powder Foundation

Naoko Ikeda,1* Kyoko Miyashita,1 Rie Hikima,1

Shoji Tominaga2

1 Make-up Research Laboratory, Kanebo Cosmetics, Odawara-Shi, Japan

2 Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan

Received 20 September 2011; revised 18 February 2012; accepted 11 April 2012

Abstract: This article aims to identify the essential com-ponents of the luminosity of skin coated with powderfoundation, based on two processes: reflection measure-ment and visual evaluation of the skin surface. The lumi-nosity refers to the state of being ‘‘luminous,’’ ‘‘brilliant,’’or ‘‘radiant’’ of the foundation-coated skin. First, a flatpiece of artificial skin is used, and an experimental deviceis developed to visually evaluate the appearance of thefoundation-coated artificial skin at different conditions ofviewing angle, illumination angle, and illumination inten-sity. The luminosity score is analyzed from the point ofview of optical reflection. Next, the same assessment ofluminosity is executed for real human skin. The luminosityis evaluated for cheek and forehead coated with powderfoundation at different observation conditions usinganother experimental device. Finally, all luminosityscores are analyzed in color spaces to identify the colorregion relating to luminosity perception. � 2012 Wiley Peri-

odicals, Inc. Col Res Appl, 39, 45 – 55, 2014; Published online 31 May

2012 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/

col.21753

Key words: foundation-coated skin color; luminosity;reflection measurement; visual evaluation

INTRODUCTION

Color analysis of bare human skin and skin with founda-

tion has been an extremely popular research topic in

many fields including color reproduction, image process-

ing, computer graphics, and the development of cosmet-

ics.1–3 One study, for example, considered the relation

between colorimetric value and appearance of skin color

using a color patch image.4 Another study used the

Kubelka-Munk model to reproduce human skin color in

3D models.5 This article focuses on skin surface coated

with cosmetic foundation, with the aim of evaluating

‘‘luminosity’’ as perceived by humans.6 The definition of

‘‘luminosity’’ depends on the field of study. In physics, it

means the ratio of luminous flux to radiant flux at the

same wavelength (e.g., see http://www.answers.com/topic/

luminosity), and in astronomy, it means the ratio at which

a star radiates energy in all directions. However, in the

cosmetic industry, luminosity refers to the state of skin

being ‘‘luminous,’’ ‘‘brilliant,’’ or ‘‘radiant.’’

Foundation is a ‘‘color cosmetic’’ recognized to havethe essential purpose of evening the tone of facial skin. It

is used as cosmetic preparation applied to bare humanskin. It has various purposes: (1) it makes the color and

texture of the skin more even, (2) it smoothes over pores,

(3) it can be used to cover up blemishes and wrinkles,and (4) it can enhance skin tone by changing the thick-

ness of foundation. Additionally, foundation can improvethe appearance of the skin surface with luminosity, and so

it is important to evaluate how foundation changes the

appearance of the skin surface.

In Japan, powder foundation is particularly popular.

Sixty to seventy percent of purchasers choose powder

foundation. Because this market is so large, we selected

powder foundation as the main focus in this article. Pow-

der foundation is composed mainly of powder and a small

amount of binder. Appearance of skin surface coated with

foundation, changes with the intensity of light reflection.

In this case, surface reflection differs according to the

type of powder and the distribution of powder. Strong

*Correspondence to: Naoko Ikeda (e-mail: [email protected]).

VVC 2012 Wiley Periodicals, Inc.

Volume 39, Number 1, February 2014 45

light reflection to the smooth surface of inorganic substan-

ces such as metal and plastic often causes luster, specular

highlight, or glow as shown in Fig. 1. On the other hand,

Fig. 2 shows surface appearances of skin with powder

foundation. The surface appearance with foundation is

different from reflection that is described as luster or

specular highlight. The surface appearance of foundation

can be best described by words like radiant, brilliant, or

luminous (English), ‘‘eclat’’ (French), ‘‘schimmern’’

(German), or ‘‘tsuya’’ (Japanese).

Visual evaluation of the surface appearance could be

perceived by humans as it corresponds to the optical

reflection characteristics. In this article, this special state

of a reflective skin surface is expressed by the word

‘‘luminosity.’’ Luminosity is now increasingly used to

highlight the benefits of foundation. The luminosity of

foundation-coated skin represents a better quality sur-

face appearance than bare human skin and therefore

gives a good public impression. Applying foundation

gives luminosity and thus improves the appearance

of the skin. It significantly enhances the impression

created.

Various methods of visual evaluation are used for eval-

uating foundation-coated skin:

1. Real human skin coated with foundation7

2. Camera images obtained using multiple resolution

analysis8

3. Three-dimensional computer graphics simulating facial

skin coated with foundation9

Although use of real human skin is preferable, we

should note that when the luminosity of human skin

coated with foundation is evaluated, various factors affect

the appearance of the foundation. These factors include

temporal changes in the foundation due to sebum (skin

oil) and sweat, and changes in the color of the skin due

to the physical condition of the human skin. The factors

hinder the detailed analysis of the visual evaluation based

on camera images and computer graphics. Therefore, vis-

ual evaluation does not effectively represent the luminos-

ity of skin surface coated with foundation.

This article aims to identify components of the lumi-

nosity of skin, with the application of powder foundation

based on two processes: visual evaluation and measure-

ment of optical reflection characteristics. We propose a

method for visual evaluation using a special device and

artificial skin coated with foundation, for the purpose of

improving the precision of visual evaluation. The merit of

this method lies in the fact that the foundation itself does

not change, and actual, thinly applied foundation can be

assessed. We use visual evaluation to assess luminosity

and analyze its relationship to the physical amount of op-

tical reflection and the color values. In addition, we assess

the luminosity on human skin. An experimental device is

developed for observing the foundation-coated surface of

human skin. The luminosity score is evaluated on the

cheek and forehead. Finally, the evaluation results of the

luminosity are analyzed in a color space. We discuss the

relationship between the luminosity score and the color

values.

In the following, the first stage is the detailed luminos-

ity observation using artificial skin. We make samples of

artificial skin coated with foundation and measure its

reflection characteristic. We develop a special experimen-

tal device and perform the visual evaluation of luminos-

ity, by changing the conditions such as viewing angle,

illumination angle, and illumination intensity. All these

conditions affect the appearance of the skin surface. Then,

we investigate the relationship between the luminosity

score and the surface reflection characteristics. The sec-

ond stage is based on the use of human skin. We evaluate

the luminosity for cheek and forehead coated with foun-

dation by using another experimental device at different

observation conditions. The third stage is to summarize

the luminosity data and analyze the factors in color

spaces.

FIG. 1. Examples of strong light reflection on a metal andplastic surface.

FIG. 2. Example of surface appearance of skin with pow-der foundation.

46 COLOR research and application

REFLECTION MEASUREMENT AND VISUAL

EVALUATION USING ARTIFICIAL SKIN

Sample Preparation of Artificial Skin

Figure 3 plots the distributions of skin tones for Cauca-

soid women and Mongoloid women in the lightness-hue

coordinates (L*, h) of the CIE-LCh color system by refer-

ring to the Kanebo Cosmetics database. Two circles with

pink and black depict roughly the distribution areas for

Mongoloid and Caucasoid, respectively. The tone coordi-

nates of artificial skin used in this article are indicated by

the filled circles with red in the figure. Note that the tone

coordinates are within a common range of Caucasoid

women and Mongoloid women.

We used a 13 3 19.5 cm2 piece of artificial skin with the

tone coordinates (Beaulax Co., Bio-Skin) as the medium for

application of foundation. The artificial skin was attached to

a matte black acrylic board (14 3 21 cm2) as shown in Fig.

4. It was maintained at a constant temperature and had a

constant surface reflectance. Figure 4(a) shows the powder

foundation used in this study. We used a sponge to apply a

0.3 mg/cm2 layer of the foundation to the artificial skin as

shown in Figure 4(b). The thickness ranged from 5 to 10

lm, which is considered to be extremely thin as a founda-

tion layer. We set the observation area to an area of 5.5 3

5.5 cm2 at the center of the artificial skin. To perform this,

a black drawing paper with a square window covered the

skin surface as shown in Fig. 4(c).

Reflection Measurement

A Gonio-spectrophotometer (Murakami Color Research

Laboratory GCMS) was used for measuring the spectral

radiance factor of the foundation-coated surface. Sensor

model of the Gonio-spectrophotometer is a double beam

system. The sensor position is fixed, and the light source

is set to be able to rotate around the sample as shown in

Fig. 5. The sample table has two degrees of freedom on

rotation and flapping. The spectral distribution of the

reflected light is observed by the sensor of a concave dif-

fraction grating. For obtaining spectral reflectance, a per-

fect diffuser is illuminated in the same way as the given

surface, and the radiance is observed in the same geome-

tries. The ratio of the radiance from the sample to the

radiance from the reference diffuser is outputted as reflec-

tance. The reflection characteristics of the surface were

measured with a combination of 81 viewing angles hv

(280, 278, . . . , 22, 0, 2, . . ., 78, 80) and 7 incidence

angles hi (0, 10, . . ., 60).

Figure 6 shows the spectral radiance factors measured

from the sample. Figure 6(a) is a 3D perspective view

that sets at the incidence angle of 108, where the spectral

curve is depicted as a function of the viewing angle.

Although the viewing angle is an important parameter in

visual assessment, it should be noted that the spectral re-

flectance depends on the incidence angle as well as on

the viewing angle. To clarify this point further, the spec-

tral radiance factors were averaged in the visible range,

and the averaged radiance factors at different incidence

angles were plotted as a function of the viewing angle.

This figure is shown in Fig. 6(b).

The maximum of each radiance factor occurs at aspecu-

lar angle up to 408. For instance, the radiance factor at

incidence angle of 308 has a peak at the same degree of

viewing angle. When both incidence and viewing angles

exceed 408, the radiance factor rises radically.

Next, we measured luminance of reflective skin surface

at the same conditions of illumination and geometry as

the visual evaluation. A high-intensity white light-emitting

diode (LED) lamp with a color temperature of 5300 K

(NS-Lighting Co., NS-01-WL) was used as a light source

to reproduce color appearance of skin surface under the

FIG. 3. Distributions of skin tones for Caucasoid womenand Mongoloid women.

FIG. 4. Sample preparation: (a) Original foundation, (b) Artificial skin with thinly applied foundation, and (c) Artificial skincovered with a black drawing paper.


illumination condition of approximating natural daylight.

This color temperature is also assumed to be similar to

the standard situation of indoor lighting. Figure 7 shows

the spectral-power distribution of the LED light source,

which was stable during observation. The lighting area

was approximately 10 cm diameter and illuminated uni-

formly the 5.5 3 5.5 cm2 observation area (see Fig. 10).

When observing the artificial skin surface under the illu-

mination level of 600 lx, the luminance value was about

120 cd/m2 at the angles of normal incidence and viewing.

The appearance of the foundation-coated artificial skin

surface for each combination of incidence and viewing

angles is shown in Fig. 8. The set of pictures was photo-

graphed using a digital camera (Nikon Corporation

D40X) equipped with a 105 mm zoom lens under the illu-

mination of 600 lx. We have no picture at the diagonal

elements of hv ¼ 2hi in Fig. 8, because the camera angle

is the same as the light source. The colors of the founda-

tion-coated skin surfaces appear different with different

combinations of incidence and viewing angles.

A noncontact spectroradiometer (Topcon Corporation

SR-3) was used for luminance measurement of these

surfaces at the same viewing angle as that of the evalua-

tors and the same light source. The meter was placed at a

distance of 60 cm from the surface, and the measured

area was a diameter of about 2 cm, corresponding to a

visual field of 2.08. The angular conditions were based on

the combination of 15 viewing angles hv ¼ 270, 260,

. . ., 210, 0, 10, . . ., 70 and 7 incidence angles hi ¼ 0,

10, . . ., 60. The luminance values (cd/m2) measured at

the respective conditions are summarized in Fig. 9. These

curves show similar characteristics to the radiance factors

measured with the goniophotometer given in Fig. 6.

Visual Assessment

Method. Evaluators were seven specialists from the

cosmetic industry who specialized in the fields of skin

and foundation. Figure 10 shows the evaluation scene

FIG. 5. Measuring geometry of surface reflectance of theartificial skin.

FIG. 6. Reflectance measurements from the sample: (a)3D perspective view of spectral reflectance at yi ¼ 10 and(b) Averaged radiance factors at different incidence anglesplotted as a function of the viewing angle.

FIG. 7. Spectral distribution of LED light source used.

FIG. 8. Appearance of the foundation-coated artificial skinsurface under different angles of incidence and viewing.


using an experimental device in a dark room, where the

foundation-coated artificial skin was affixed vertically to

the device and an evaluator was sitting about 60 cm dis-

tant from the surface. The device consisted of two rota-

tion stages. The target object of artificial skin was on one

360-degree precision rotation stage (Chuo Precision

Industrial), which orientation could be changed smoothly

and arbitrarily in relation to the evaluator. The light

source was fastened to another stage at a distance of 30

cm from the center of the artificial skin and rotated hori-

zontally 3608 at a fixed distance. The angle of illumina-

tion could be changed arbitrarily, independently of the ar-

tificial skin. The height of the light source was set to the

eye level and the evaluator’s chair was placed at 08 in

relation to the skin surface. The evaluator maintained the

correct distance from the sample by keeping a constant

posture.

To make the visual assessment of luminosity, a com-

mon framework of the concept of luminosity was defined

to all the evaluators as: ‘‘Surface appearance of the foun-

dation applied skin has a natural feeling and a surface

gloss that is neither too strong nor too faint.’’

To give clear instruction to the evaluators, we set the

degree of luminosity perception level with a score of 0–5:

Level 0 means that the evaluators observed no luminosity

at all, level 1 indicated a weak luminosity, level 3 a me-

dium luminosity, and level 5 a strong luminosity. The

instruction scenes of luminosity levels 1, 3, and 5 were

given to the evaluators as the typical examples for coding

(see Fig. 11). The three levels were created at the angle

pairs (0, 240), (0, 220), and (5, 0) of (hi, hv).

When two angles of incidence and viewing changed,

the evaluators were asked to answer the luminosity level

with a score of 0–5. The average of the scores obtained

from all evaluators was used for the analysis. The same

surface was observed at a set of angular conditions that

combines all the 15 viewing angles changing from 270

to 70 in 108 increments and the 7 incidence angles chang-

ing from 0 to 608 in 108 increments.

The possible time for the experiment was considered at

most 40–45 min per each evaluator to avoid the evalua-

tors’ fatigue. In practice, 35–40 min were required for

each evaluator, where about 5 min were to give the

instruction of luminosity and 30–35 min were to observe

the artificial skin surface at different 105 angular condi-

tions. This evaluation experiment was repeated under dif-

ferent illumination intensities. We switched vertical illu-

mination between 600, 400, and 200 lx. There is only one

experiment under one illumination per day. Therefore, the

time required for every evaluator was within 40 min per

day.

Evaluation results. The average score for luminosity at

the normal incidence hi ¼ 0 at each illumination level

(600, 400, and 200 lx) is shown in Fig. 12. This shows

that when the illumination decreases, the luminosity also

decreases. Next, the score for luminosity at each illumina-

tion level is shown in Fig. 13. Figure 13(a) represents the

set of curves of the luminosity score at different incidence

angles under the light source of illuminance 600 lx. ItFIG. 10. Evaluation scene using an experimental device.

FIG. 9. Luminance measurements from the sample.

FIG. 11. Instruction scenes of luminosity levels 1, 3, and5.


should be noted that the luminosity score seems to make

peak at the specular reflection angle when the incidence

angles are small (0, 10, 20, and 30), and then seems to

take peak at viewing angles smaller than the specular

reflection angle when the incidence angle are large (40–

60). The same features are observed at 400 lx and even at

200 lx in Figs. 13(b) and 13(c).

However, note that in Figs. 6(b) and 9 radiance factor

and luminance peak at the specular reflection angle and

then rise nearly geometrically with the increase in the view-

ing angle when the incidence angle is to 508 or more.

These results suggest that the peak of luminosity is not

necessarily observed at the specular reflection angle, and

stronger specular highlight is not always associated with

higher luminosity perception. This property will be ana-

lyzed also for human skin in color spaces later.

VISUAL EVALUATION USING HUMAN SKIN

Sample Preparation

The next evaluation used the cheek and forehead of a

woman of her late 20s. The skin tone coordinates of her

cheek and forehead are indicated by the filled circles with

blue and green, respectively, in Fig. 3. We note that the

skin tone coordinates of this test subject are located in the

center for the Mongoloid women and are also within the

range for the Caucasoid women. The visual evaluation of

the foundation-coated skin for another two Mongoloid

Japanese women was performed, and it was believed that

all cases had the same characteristics.

Powder foundation was applied to the cheek and fore-

head of the woman with a sponge after skin care. The

foundation-coated surface was observed in 3.0 3 3.0 cm2

areas of the center of the cheek and forehead. Figure 14

shows pictures of the cheek and forehead coated with

powder foundation.

Luminance of the foundation-coated surfaces of the

human cheek and forehead was measured at multiple

angles in the same way as the measurement of the artifi-

cial skin surface. In this experiment of the foundation-

coated human skin, the illumination of 900 lx was used,

and in this case, the intensity (luminance) observed at the

angle (0, 0) was about 120 cd/m2. Note that the visible

area becomes narrower as the viewing angle increases

because human face is a curved surface. Our spectroradi-

ometer had selections of visual field of 0.1, 0.2, 1.0, and

2.08 for measurement. Therefore in this article, the lumi-

nance measurement was done in the visual field of 0.28,corresponding to the diameter of 2 mm on the surface.

Evaluation Method

Figure 15(a) shows the device structure for observing

the foundation-coated surface of human skin. The rotation

device allowed the incidence angles and viewing angles

to change arbitrarily. A black plastic board with a square

window was prepared to observe the area of 3.0 3 3.0

FIG. 13. Average score of luminosity at specific illumina-tion levels.

FIG. 12. Average score of luminosity at each illuminationlevel.


cm2 of the cheek and forehead. To avoid the specular

reflection, the plastic board around the window was cov-

ered with a black drawing paper and affixed vertically to

the center of the device.

The light source was the same white LED lamp as before,

which was affixed to the device to be rotated horizontally. The

cheek and forehead of the test subject were touched lightly to

the black board and the surface appearance was observed

through the window. The orientation of the board could be

changed arbitrarily, independently of the light source.

The five evaluators assessed the luminosity of the foun-

dation-coated human-skin surface as shown in Fig. 15(b).

The luminosity level of the human skin was then judged

with the same luminosity score of 0–5 as the one for the

artificial skin. The visual assessment was performed under

the vertical illumination of 900 lx at 60 angular conditions,

which were the combination of 12 viewing angles hv ¼270, 250, 240, 230, 210, 0, 10, 30, 40, 50, 60, 70 and

5 incidence angles hi ¼0, 10, 20, 40, 60. As it is very diffi-

cult for the test subject to maintain the same position dur-

ing the evaluation, the number of incidence angles and

viewing angles was reduced than the case of the artificial

skin, considering the possible temporal change in the foun-

dation, as well as to reduce evaluator and test subject fa-

tigue. We removed hv ¼ 260, 220, 20 and hi ¼30, 50,

since the luminosity score varies smoothly.

Before the evaluation, the same instruction of luminos-

ity score was given again to each evaluator. The experi-

ment using human face takes twice the time compared to

artificial skin. Under the current experiment, it was neces-

sary for each evaluator to evaluate the luminosity of

human skin at 60 different angular conditions, which took

�40 min for each of the cheek and forehead. This evalua-

tion experiment was conducted only once a day to avoid

the subject’s fatigue. The average of the scores obtained

from all evaluators was used for the analysis.

Evaluation Results

Foundation-coated human skin was analyzed by chang-

ing incidence and viewing angles in the same way as in

FIG. 15. Experimental scenes for observing foundation-coated human skin.

FIG. 14. Pictures of the cheek and forehead coated withpowder foundation.


the artificial skin analysis. The color of the skin appeared

differently with different combinations of the incidence

and viewing angles, as shown for the cheek in Fig. 16. It

shows a 2D array of color images of the foundation-

coated human skin surface, which were photographed

with the same camera at several angles of light-incidence

and camera viewing. The color appearance of the skin

surface depends on the two stated angles.

Figure 17 shows the average scores of the luminosity for

the human skin samples at the two positions of cheek and

forehead under the illumination of 900 lx. These curve

shapes are not necessarily the same as the curves evaluated

for the artificial skin. Because human skin surface is

slightly curved, the angular dependence of the luminosity

may not be as clear as the flat artificial skin surface. How-

ever, we can find a similar feature to the luminosity evalu-

ation to the artificial skin. The maximum luminosity seems

to appear at specular reflection angle only when the inci-

dence angle is small, and the specular highlight does not

always associate with stronger luminosity perception.

COLOR SPACE ANALYSIS OF LUMINOSITY

Luminosity is analyzed in different color spaces to

explore other color factors besides reflection intensity

involved that contribute to the luminosity perception.

Chromaticity Distribution of Foundation-Coated

Artificial Skin

The CIE-XYZ tristimulus values of the foundation

coated artificial skin were obtained under all conditions of

angles and illumination intensities. Figure 18 shows the

chromaticity distribution of all observed data on the CIE-

FIG. 16. Appearance of foundation-coated cheek surface at different angles of incidence and viewing.

FIG. 17. Luminosity scores for real human skins: (a)Cheek and (b) Forehead.

FIG. 18. Chromaticity distribution of all observed data onthe CIE-xy diagram.


xy chromaticity diagram. The luminosity scores at

different observation conditions are classified in five colors

segmented in the interval of [0, 5]. All the chromaticity

points fall into a straight line from the light source. We note

that hue does not change even if the observation conditions

vary. In this case, a distance Cxy ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffix� x0ð Þ2 þ y� y0ð Þ2

q

from the light source coordinates (x0, y0) corresponds to the

chroma component of skin color, although it is not neces-

sarily a perceptually uniform scale. The luminosity score

looks different with the chroma. In the following, the lumi-

nosity is analyzed on the 2D coordinate system of lightness

(luminance) and chroma.

Luminosity of Foundation-Coated Artificial Skin in

CIE-Yxy Coordinates

First, we analyze the luminosity perception in the CIE-

Yxy coordinate system. In Fig. 19, all the observed color

values from the foundation-coated surface are plotted in the

coordinates of luminance Y (cd/m2) and chroma Cxy. The lu-

minosity is not perceived at both low luminance and high

chroma like (Y \ 50, Cxy [ 0.05), or high luminance and

low chroma like (Y [ 50, Cxy \ 0.02). The luminosity is

perceived well where both chroma and luminance are mod-

erately high as indicated by the red ellipse. We note that

neither the bright skin surface with the highest luminance

nor the saturated skin surface with the highest chroma

would always result in the luminosity perception. This result

suggests that chroma as well as luminance is an important

factor of the color component in the perception of luminos-

ity. We note from Figs. 19 and 13 that the luminosity is

perceived even at the very low light level like 200 lx. We

consider that it is caused by the effect of dark adaptation of

visual system to the reduced illumination environment.

Luminosity of Foundation-Coated Artificial Skin in

CIE-LCh Coordinates

The LCh color space uses the same diagram as the

CIE-LAB color space but uses cylindrical coordinates

instead of rectangular coordinates. This space approxi-

mates a perceptually uniform color space and is independ-

ent of the illumination environments by assuming perfect

adaptation of the human visual system to the lighting con-

ditions. The rectangular coordinates (L*, a*, b*) are

defined as

L� ¼ 116 Y=Y0ð Þ1=3 � 16

a� ¼ 500 X=X0ð Þ1=3 � Y=Y0ð Þ1=38: 9;

b� ¼ 200 Y=Y0ð Þ1=3 � Z=Z0ð Þ1=38: 9;

9>>=>>;; (1)

where (X0, Y0, Z0) are the tristimulus values of a standard

white reference to produce the normalized (X, Y, Z) val-

ues. The chroma C* is defined in cylindrical coordinates

as C� ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffia�2 þ b�2p

. Figure 20 shows all the observed

color values plotted in the coordinates of lightness L* and

chroma C*, according to the luminosity scores. It is

noticed that the lightness is relatively high where lumi-

nosity was perceived as indicated by the red ellipse. On

the other hand, the lightness is relatively low like L* \75 and too high L* [ 100 where luminosity was not per-

ceived as indicated by the blue boundary. The detail

inspection shows that the luminosity is perceived at the

small region of 80 � L* � 100 and 10 � C* � 20.

Roughly speaking, the luminosity is perceived in the

region of relatively high lightness and moderately high

chroma except for the saturation extreme.

Luminosity of Foundation-Coated Human Skin

We analyzed the luminosity of foundation-coated

human skin with the same manner as in the artificial skin

analysis. The luminosity scores for the skin surfaces of

cheek and forehead are plotted using the five color sym-

bols in the (L*, C*) coordinates in Figs. 21 and 22,

respectively.

The luminosity is neither perceived at low lightness and

high chroma like the region where L* \ 60 and C* [ 15,

nor at high lightness and low chroma like the region where

FIG. 19. Luminosity in the CIE-Yxy coordinates.

FIG. 20. Luminosity in the (L*, C*) coordinates.


L* [ 80 and C* \ 15. The red ellipses in Figs. 21 and 22

indicate where the luminosity is well perceived. In this

region, the lightness is relatively high, and the chroma is

moderately high. The blue ellipses indicate the regions

where the luminosity is not well perceived in the color

space. We note that the luminosity is not perceived in the

highest lightness region, and not perceived well in the

highest chroma. These characteristics are the same with the

previous evaluation results using artificial skin.

CONCLUSION

This article presents the components of the luminosity of

skin coated with powder foundation, based on reflection

measurement and visual evaluation of the skin surface.

The luminosity refers to the state of being ‘‘luminous,’’

‘‘brilliant,’’ or ‘‘radiant’’ of the foundation-coated skin.

First, we used a flat piece of artificial skin. An experi-

mental device was developed for visually evaluating the

appearance of the foundation-coated artificial skin at dif-

ferent conditions of viewing angle, illumination angle,

and illumination intensity. The luminosity score was ana-

lyzed from the point of view of optical reflection. Next,

the same assessment of luminosity was executed for

human skin. The luminosity was evaluated for cheek and

forehead coated with powder foundation by using another

experimental device. At last, all luminosity scores were

analyzed in color spaces to identify the color region relat-

ing to luminosity perception. The analysis results are

summarized in below sections.

Luminosity as a Function of Optical Reflection

The luminosity is perceived even though the illumination

level is low around 200 lx. The luminosity score increases

as the illumination level increases in the range of 200–600

lx. Concerning the observation geometries, the luminosity

is well perceived at the specular reflection angle when illu-

mination is incident from the surface normal direction or at

a small incidence angle. It is well perceived at an angle

smaller than the specular angle when the incidence angle

becomes large like far aspecular illumination.

Luminosity in Color Space

The luminosity perception is more intense when both

lightness (luminance) and chroma increase. It is weak if

either lightness or chroma is extremely high. It is neither

perceived at low lightness and high chroma, nor at high

lightness and low chroma. It is perceived in the region of

relatively high lightness and moderately high chroma. The

chroma is a vital factor in the luminosity perception as

well as lightness and luminance.

Luminosity is a positive term giving good impression

to human face where it can be achieved by applying foun-

dation. The above results suggest that powder foundation

can give a luminosity effect that could be perceived not

only in the condition of bright daytime but also in the

condition of low-light nighttime. It is possible to develop

powder foundation by controlling the color coordinates,

which creates a good impression of luminous skin in the

various conditions that can be expressed in daily life.

This article has focused on the luminosity of powder

type foundations, in which reflection is caused by fine

particles. This is the first study to analyze the details of

foundation-coated skin at different observation angles.

This study seeks to explain factors of luminosity, and we

believe that the findings enable new expansion in color

science research.

1. Tominaga S, Moriuchi Y. Principal component analysis-based reflec-

tance analysis/synthesis of cosmetic foundation, J Imag Sci Technol

2009;53:1–8.

2. Angelopoulou E, Molana R, Danilidis K. Multispectral skin color

modeling, Proceedings of the IEEE Conference on Computer Vision

and Pattern Recognition, Hawaii, USA; 2001. p 635–642.

3. Tsumura N, Ojima N, Sato K, Shimizu M, Nabeshima H, Akazaki S,

Hori K, Miyake Y. Image-based skin color and texture analysis/syn-

FIG. 21. Luminosity in the (L*, C*) coordinates for cheek.

FIG. 22. Luminosity in the (L*, C*) coordinates for fore-head.


thesis by extracting hemoglobin and melanin information in the

skin, ACM Trans Graphics; 2003;22:770–779.

4. Yoshikawa H, Kikuchi K, Kim J, Nishikawa S, Yaguchi H, Mizo-kami Y. Effect of the chromatic components on the whiteness evalu-ation of skin, Midterm Meeting of Congress of International ColourAssociation (AIC); 2007. p 203–206.

5. Doi M, Tanaka N, Tominaga S. Spectral reflectance estimation of

human skin and its application to image rendering. J Imag Sci Tech-

nol 2005;49:574–582.

6. Ikeda N, Hikima R, Tanno O, Tominaga S. Measurement of reflec-

tion and visual evaluation of the luminosity of skin with foundation

applied, Proceedings of the Congress of International Colour Associ-

ation (AIC), Sydney, Australia; 2009. p 1–8.

7. Nishimura H, Takasuka Y, Yamamoto M. Optical properties of skin

gloss and development of mizumizushii-looking makeup foundation,

Proceedings of the International Federation of Society of Cosmetic

Chemists (IFSCC) International Congress, Orlando, USA; 2004. p

307–311.

8. Fujii M, Misaki Y, Sasaki I. Application of image processing tech-

nique for facial gloss evaluation, Proceedings of the International

Federation of Society of Cosmetic Chemists (IFSCC) International

Congress, Orlando, USA; 2004. p 302–306.

9. Minami K, Kaneko T, Nabeshima H, Iwamoto H, Ojima N, Nagatani

N, Hori K. Evaluation of glossy appearance of facial make-up using

CG images. Int J Cosmetic Sci 2005;27:251–252.


Reflection measurement and visual evaluation of the luminosity of skin coated with powder foundation

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