CLINICAL TECHNIQUE

Shade Matching

A Technique Using Calibrated Photography

and Photoshop for Accurate Shade Analysis
and Communication
Edward A. McLaren, DDS, MDC; Johan Figueira, DDS; and Ronald E. Goldstein, DDS

Abstract: This article reviews the critical aspects of controlling the shade-taking environment and discusses
various modalities introduced throughout the years to acquire and communicate shade information.
Demonstrating a highly calibrated digital photographic technique for capturing shade information, this article
shows how to use Photoshop® to standardize images and extract color information from the tooth and shade
tab for use by a ceramist for an accurate shade-matching restoration.

D
ental shade analysis, effective communication of coverage of natural tooth color.8 There is also no industry standard-
tooth color, and, most importantly, the reproduc- ization among shade systems and corresponding porcelain systems.
tion of natural tooth color in a final restoration that Finally, the highly complex nature of color distribution within a
mimics the adjacent tooth structure have long been tooth and how form, surface texture, and gloss affect perception
highly sought-after, yet elusive, goals for dental pro- of colors all contribute to these complications. Various references
fessionals. Shade-matching systems have been slow to evolve, and
1-4
are available in both the dental and non-dental literature on the
gathering effective and complete shade information remains more topic of color as it relates to teeth and human perception of color
of an art than a science. Several digital shade analysis devices have that can help clinicians gain a better understanding of the many
been introduced to the market, but their main use is for posterior variables that interact to create and control color perception,1-4,6,7,8
tooth-shade analysis and possibly for a base-shade analysis of ante- but the focus of this article will be on a highly calibrated digital
rior teeth to be employed along with adjunctive digital photography photographic technique for capturing shade information.
and visual shade analysis modalities.5 Numerous articles1-4,6,7 and at
least one book8 have been devoted to these topics, yet in the authors’ Digital Photography’s Impact
opinion, based on many discussions with dental technicians, shade In the past few years, digital photography has become a valuable
analysis remains one of the top reasons for remakes, second only tool in dentistry for the communication of information, especially
to impression/preparation problems. tooth color. Just like with visual shade analysis, many aspects to
Many factors contribute to the difficulty in achieving accurate proper imaging and camera set-up must be controlled to attain
shade analysis, effective color communication, and precise re- an accurate image that can be used for color analysis. In addi-
production of natural tooth color in final restorations. Most criti- tion, all cameras record differently,10 and, unbeknownst to many
cally, different lighting conditions affect the perception of color. practitioners, various technologies utilized by digital cameras
Agreement in the industry is lacking even with regard to which types produce diverse color values when recording the same image, even
of light and viewing conditions are best suited for visual shade anal- under identical conditions.9-11 Thus, it is important to choose a
ysis, although environmental viewing conditions for visual shade- camera that allows a customizable white-balance setting, which is
taking can be better controlled with a thorough understanding of a function that can significantly help compensate for color differ-
lighting and its effect on color perception.9 Other hindering factors ences due to technology variations among cameras. (Authors’ note:
include individual human variables in color perception, lack of un- Information on camera and flash selection and specific camera
derstanding of color science particularly as it relates to tooth shade, settings, especially for general dental photography, is provided
and commercially available shade systems providing incomplete in great detail in other articles,11-13 and the reader is encouraged

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to review these references.) The most important points of good
dental photography are as follows: (1) use a digital single-lens re-
flex (SLR) camera that allows interchangeable lenses; (2) record
shade images in RAW file format; (3) utilize custom white bal-
ance; and (4) employ manual exposure for shade images. When
performing this fourth point, the same magnification ratio should
be used for all shade images on all patients, and the flash should
be set the same distance from the teeth. When setting the flashes
and camera in manual modes, the user will have to experiment
with the flash output to find the right amount of flash power for
the proper exposure; once found, the exposure will always be the
same, as the settings will remain in manual—this is assuming the
camera settings are identical and the camera and flash distance
from the teeth remain unchanged. Fig 1.
Highly effective photograph editing software programs have
come on the market and today play significant roles in virtually
every industry, including dentistry. The authors could find only one
article that compared digital photography to colorimeter for L*a*b*
(L* refers to lightness, a* indicates red and green, and b* represents
yellow and blue) values for measuring color and found the former
to be accurate as long as lighting and camera settings were con-
trolled.14 (Although previously, the authors indicated all cameras
record color differently, they will later discuss using a specific gray
card and specific adjustments in Adobe Camera Raw.) Little has
been written about the potential benefits of Adobe Photoshop® in
shade-taking, the shade analysis process, and the final fabrication
of the restoration. Throughout the years, the authors have devel-
oped a technique that combines calibrated photography with the Fig 2. Fig 3.

use of existing shade guides and post-processing in Camera Raw

and Photoshop to evaluate and extract color information that is Fig 1. Image showing correct relationship of shade tabs to evaluated
tooth. They need to be in the same vertical plane as the tooth evaluated.
used directly in choosing correctly shaded restorative materials Fig 2. Shade tab in same plane as tooth. Fig 3. This is the same shade
for a final restoration. tab as shown in Figure 2 except here the tab was placed approximately
The purpose of this paper is threefold: (1) review how to control 3 mm behind the tooth. Note the difference in perception of color.
or optimize the shade-taking environment; (2) demonstrate an
exact shade-taking photographic protocol; and (3) discuss proper
computer screen calibration and the use of Adobe Camera Raw ing environment that is close to 5,500 K, ie, if the shade guide being
and Photoshop shade analysis. used is made to match under a 5,500 K light, then that is the light
that should be used to match. In the authors’ experience, if the
Optimizing the Shade-Taking Environment shade guide is matched to the teeth in a 5,500 K light, then it will
To optimize the shade-taking environment, it is best to try to match match well in most lights; however, if it was matched in a strongly
color under the conditions that the restoration will most likely be biased light (eg, blue), the restoration will match only in that light.
seen. Relative to tooth position, most people’s teeth are viewed in Several commercial companies sell 5,500 K fluorescent tubes
a vertical position at a conversational distance. This is the optimal that fit in standard fixtures in a dental office, and many compa-
position to place the patient to evaluate shade,15 ie, perform the nies manufacture color-corrected florescent lights. Full-spectrum,
shade analysis with the patient in a vertical position, eye to eye with color-corrected lights with a color temperature of 5,500 K are best
the clinician, at a conversational distance. Humans are exposed suited for visual shade-taking.8,12 It would be ideal to outfit an opera-
to many types of light, and so are their dental restorations. When tory with this type of lighting; however, a more inexpensive way to
shade guides are manufactured, they are compared to a standard in control light is to use two magnification lamps (eg, Ottlite®, Ottlite
a controlled lighting situation. Which color temperature light, eg, Inc., ottlite.com) held approximately 24 inches from the patient
5,000 K, 5,500 K, or 6,500 K, to use to take a shade has been a point at tooth level. Another option is to use a commercially available
of debate. Most shade guides are fabricated to match a standard in handheld device (Smile Lite, Smile Line USA, smilelineusa.com)
a 5,500 K light source. Shade guides do not have the same optical that also has a 5,500 K temperature light. Yet another alternative
properties as natural teeth, therefore they do not reflect light the is a handheld color-corrected device (Rite-Lite 2™ HI CRI Shade
same in all lighting conditions as the corresponding shaded tooth Matching Unit, AdDent Inc., addent.com) that allows the user to
would. Thus, visual shade matching should be done only in a light- take the shade at 5,500 K and offers other valuable light settings.

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Clinical Technique | Shade Matching

A critical aspect of controlling the shade analysis environment is ferences in human perception and color readings in Photoshop.
that the teeth need to stay hydrated, because dehydrated teeth ap- In Figure 2 and Figure 3, notice how when the shade tab that is
pear much brighter.5 Saliva dries quickly, especially with cheek retrac- an apparent match is moved to a different plane than the natural
tors in place. The authors use a medium-viscosity clear glaze liquid (eg, tooth, the illumination is different. This is a critical aspect that
Smile Line Glaze, Smile Line USA) to wet both the teeth and shade must not be overlooked. (Authors’ note: To compensate for the fact
guide8,12 and have found this to be helpful. It is important to wet both, that digital cameras record light differently, the authors will later
because differences in surface texture between the shade guide and discuss the use of a gray card and color balance as workarounds.)
tooth can create a misperception.8,9,12 Having the same liquid on both Shade-guide positioning and surface reflectance are important
surfaces can neutralize this. In summary, full-spectrum 5,550 K color- issues to consider both in visual shade analysis and in shade pho-
correct lighting should be used, keeping the teeth adequately hydrated. tography. While most authors have suggested evaluating a shade-
guide incisal edge to incisal edge,5,16,17 the authors have found that
Exact Shade-Taking Photographic Protocol very few incisal edges of shade guides actually match natural teeth,
Digital photography is one of the most powerful tools in communicat- and this can lead to an incorrect assessment of color; therefore,
ing shade information. The use of photography for communicating they recommend evaluating with both the necks and incisal edges
with patients and the dental ceramist has been well documented.9,10,12 of the shade guide against the natural tooth. Also, it is difficult to
To use digital images to determine or analyze shade, the image of hold the incisal edge of the shade guide against the incisal edge
the tooth being compared and the shade guide need to be in the of the natural tooth; it must be kept stable with both in the same
same vertical plane and must be illuminated evenly, ie, the shade plane, and then a photograph taken. The authors have found that
guide cannot be closer to or farther from the digital film plane than significantly flattening the neck of the shade guide creates a “step,”
the tooth (Figure 1). Also, there should not be differing amounts or “shoulder,” that will act as a perfect seating device against the
of light on the shade guide and teeth, because this will cause dif- incisal edge of the natural tooth to allow for an ideal image (Figure

Fig 4. Fig 5.

Fig 6. Fig 7.

Fig 4. This image demonstrates seating of the shade tab using a shoulder, which was created in the tab. Fig 5. Metal tab holder that has had tab
removed. Gray card is held on tab with clear utility wax. Fig 6. Histogram after the exposure has been idealized using the WhiBal gray card. Fig 7.
Nikon R200 flash with corresponding shape of a sheet linear polarizer taped on.

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4). The shade guide is then adjusted with a laboratory diamond for
porcelain or a course disc designed to contour porcelain, then pol-
ished with porcelain polishing instruments (eg, Dialite®, Brasseler
USA, brasselerusadental.com).
When taking the image, the authors use a gray card for subsequent
exposure calibration in Adobe Camera Raw (which is packaged
with Photoshop). They have found the most accurate card to be
the WhiBal® card (Michael Tapes Design, michaeltapesdesign.com),
which has an L value between 74 and 75 as measured in the CIELAB
color model.18 They cut the WhiBal card into small squares, each ap-
proximately 1 cm x 1 cm, then attach a square to a shade tab handle
using clear utility wax (Figure 5). The Vita 1M1 shade guide (VITA,
Fig 8.
vitanorthamerica.com) when photographed in the same plane as
the WhiBal card and illuminated and exposed in the same man-
ner enables the exposure of the gray card to read 73/74 in Adobe
Camera Raw in the middle one-third of the tab. The authors found
an interesting correlation in that each value group decreased by a
reading of approximately three L values, eg, 2M1 would read 70/71
in Photoshop when properly exposed.
When taking the image, regardless of the shade guide used, the
shade tab chosen and the second closest shade tab are placed with
the WhiBal gray card in the image to be matched. All three are
positioned in the same vertical plane, and they should be placed
as close together as possible to get maximum illumination on all
three (Figure 1). Having both tabs plus the WhiBal card will be Fig 9.
useful later in evaluating color in Photoshop.
Doing an image capture in RAW file format is required, as this
is an uncompressed file type with the most color information and
is also easily fixable if the camera settings were set wrong initially.
Several images should be taken from slightly different angles and
with the shade guide and gray card moved laterally left and right
but kept in the same vertical plane as the natural tooth. The au-
thors also use manual camera settings: ISO 200; manual flash (the
user will have to experiment with the settings to attain the right
exposure, but generally the main point of the histogram is slightly
right of center (Figure 6); white balance set to K and temperature
5,500 to 5,700; F32 or higher. The authors recommend adjusting
the magnification (composition) until the four incisors and a little Fig 10.
more than half of each canine can be seen; this will allow good, even
lighting of the incisors, the two shade tabs, and the gray card in the
image. A linear sheet polarizer (eg, Rosco, us.rosco.com) cut to the
shape of the flash can be used on a dual-flash set-up (Figure 7). In
the authors' experience, polarizing flashes reduces the glare on the
teeth by about 30%, which improves visualization and color evalua-
tion. Polar Eyes (PhotoMed, Photomed.net) is another good cross-
polarization system. It must be emphasized that this Photoshop
shade analysis system requires exact photographic technique for
it to work effectively.

Using Cross-Polarization to Eliminate All Glare Fig 11.

Cross-polarization techniques have recently become popular for
evaluating shade.19 Cross-polarization is a process in which the user
places a polarizing filter on both the light source (ie, the flashes) and Fig 8. Image generated using the cross-polarization technique. Fig 9.
Image opened into Adobe Camera Raw. Fig 10. Changing the RBG
the lens. When this is done correctly for a dental image, ie, the polar- default readouts in Camera Raw to Lab readouts. Fig 11. Properly
izers are aligned at right angles to each other so all glare is blocked exposed image after adjustment in Adobe Camera Raw.

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Clinical Technique | Shade Matching

Camera Raw Lab Set-up

Adobe Camera Raw comes bundled with Photoshop and Photoshop
Elements. Both programs are suitable for the simple analysis that
will be done to extract color from images to be used in determining
restoration ceramic color.
Version 8 of Adobe Camera Raw or later has a feature that can
help calibrate image exposure and determine the value of the
teeth to be matched. The procedure is as follows: First, open the
image (shot in Camera RAW) in Adobe Camera Raw (Figure 9).
The histogram (Figure 9, upper right) is set to default to read
color in RGB. The default setting can be changed to read Lab color
Fig 12. Fig 13.
by placing the computer mouse on the histogram and pressing
the Control key on the keyboard. A window will open; then click
on “Show Lab Color Readouts” (Figure 10). The histogram will
change to read Lab values wherever the user places the mouse on
an image. Place the mouse on the WhiBal card nearest the tooth
you are trying to match, and move in small circles. At the same
time, look at the L value in the histogram. If the L value does not
read between 74 and 75, take the exposure slider and move it
left or right until it does. Again, this technique requires correct
positioning of guides, card, and teeth to be matched, with even
illumination on all elements. At this point, the image should now
be properly exposed (Figure 11).

White-Balance Workaround
Fig 14.
In photography, the gray card is used to measure or control expo-
sure and to white-balance images, ie, if the image has a color bias
in it, a white-balance tool in Photoshop (and other programs) can
be used to remove all color biases in the image so that the colors
represent what the viewer actually would see in color-balanced
light. In actuality, a gray card does not offer sufficient information
for any program to effectively balance color. Professionals who bal-
ance color use a system such as ColorChecker® (X-Rite, xrite.com),
which has many colors. An image is taken using the system and is
displayed, or it can be printed using a printer that is adjusted based
on the program reading the value of the registering of the colors. If
the colors are not accurate, the program creates a “color profile,”
which essentially overwrites and changes each pixel to the correct
color. With only a gray card and using the white-balance function,
Fig 15. Photoshop (and other similar programs) tends to read the card
as somewhat bluish and removes some blue from the image, thus
Fig 12. Using the color temperature and tone slider adjustments to “color turning the image slightly reddish orange. The color-temperature
correct” the image. Fig 13. Opening up the “Info” palette in Photoshop. slider moves in Camera Raw to approximately 6,500 K to 6,700 K,
Fig 14. Measuring the “S,” or saturation of the tooth and shade guide.
Fig 15. Final case in which shade information was generated using the and the tone slider to roughly plus 5.
Photoshop shade analysis technique demonstrated in this article. Through trial and error, the authors have found a simple “work-
around” to this problem. Instead of using the white balance with
the WhiBal or any gray card, they use it only for exposure con-
(Figure 8), it allows better visualization of the value and chroma and trol as intended when it was first developed. They then set the
especially the gradients of both color aspects. The authors also typi- color-temperature slider to 5,700 K and the tone slider to plus 10,
cally take images of two shade guides with the WhiBal card using the which gives, what they believe, a visually correct color (Figure 12).
cross-polarization technique with their shade-taking protocol. (Au- The reason for this is twofold. In personal communication with
thors’ note: If the reader has no experience using cross-polarization, Nikon, one of the authors (EAM) found that the SB200 flashes at
the easiest system to use is the aforementioned Polar Eyes system, one-quarter power are about 5,700 K color temperature, which is
which can accommodate both Nikon and Canon cameras and all approximately the power used for most shade images. Secondly, it
flash systems for both of these camera brands.) is the authors’ personal visual experiences on a 24-inch calibrated

112 compendium February 2017 Volume 38, Number 2

Apple monitor that, if they made the aforementioned adjustments, been directly useful in choosing the correct shades of ceramics for
the image will closely match to the subject visually when the indirect restorations.
authors sit next to the screen. Another consideration is the com-
parison of color differences from a known entity in the image, ie, ABOUT THE AUTHORS
the shade guide. Thus, the goal at this point is to quickly attain a
Edward A. McLaren, DDS, MDC
correctly exposed image with good color balance, which has now Professor, Founder, and Director, UCLA Postgraduate Esthetics; Director,
been achieved. UCLA Center for Esthetic Dentistry; Founder and Director, UCLA Master Dental
Ceramist Program, UCLA School of Dentistry, Los Angeles, California;
Private Practice, Prosthodontics and Esthetic Dentistry, Los Angeles, California
Photoshop Shade Analysis
The images are then opened into Photoshop. Although the authors Johan Figueira, DDS
measured the L value in Camera Raw, they still recommend veri- Private Practice, Caracas and Isla de Margarita, Venezuela, and Los Angeles, California

fying the L value in Photoshop. In Photoshop, the “INFO” palate Ronald E. Goldstein, DDS
must be open. If it is not, go to Window and click on “INFO” to Clinical Professor of Oral Rehabilitation, The Dental College of Georgia at Augusta
open this palette (Figure 13). Click on the small eyedropper in the University, Augusta, Georgia; Private Practice, Atlanta, Georgia

Info palate window and click on “Lab Color.” Place the mouse over
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