Spectrophotometry of Chromatic Variability in the Rock Paintings of Tecsecocha, Ccorca, Cusco

Abstract

This communication presents an approach to the chromatic study of rock painting scenes in the Tecsecocha sector, Ccorca district, Cusco, Peru, through the application of color spectrophotometry using Capsure by XRite, considered a portable device that facilitates reference measurements of color codes belonging to the visible spectrum (400–700 nm). It is evident that this methodology does not perform the physicochemical characterization of the pigments present in the rock paintings, which are cataloged as artistic heritage of the nation, making it unfeasible to extract physical samples or significantly alter the rock paintings. Therefore, the NCS color notation system allowed for the non-invasive recording of color tones. The results showed a predominance of white and red tones with variations in their shades; among the most frequent codes, S2030-Y70R and S3010-Y40R stand out, indicating yellow tones with red influences of 70% and 40%, respectively. In the anthropomorphic figures, a slight variation in the proportion of red was identified, suggesting differences in the application of pigments, while in the representations of camelids, the tones varied from S3005-Y20R (yellow with 20% red) to S2030-Y70R (greater red influence).

1. Introduction

Rock art is one of the earliest ways in which humanity expressed itself visually and is crucial for understanding the symbolic customs, techniques, and territorial aspects of ancient cultures. In the southern Andes of Peru, particularly in Cusco, there are various sites featuring these artistic expressions that depict scenes of animals, anthropomorphic figures, and geometric shapes, painted with mineral pigments applied to the rocks. These paintings, often found in caves and hard-to-reach locations, are part of a complex system of meaning that connects the landscape, rituals, and memories (Hostnig 2007; Barreda-Murillo 1995).

Research on rock art in southern Peru has increased in recent years, becoming a field that combines archaeology, cultural history, community studies, colorimetric measurement, and art preservation (Guffroy 1999; Trujillo Téllez 2020; Gheco 2019). In this regard, studying color is becoming increasingly important, as it helps to uncover technical and stylistic details of the paintings, in addition to their symbolic value. Color is not just a choice of materials, such as the selection and preparation of pigments but also a means of expressing cultural meanings, worldviews, and social contexts that need to be understood within their setting (Gheco 2019; Dupey García 2015).

In the Cusco region, places like Yucay, Livitaca, Ccorca, Huaro, and Totocahja house valuable pictorial collections, where reddish, ochre, and pale colors stand out, often linked to minerals such as hematite, goethite, kaolin, and iron oxides found in the earth of the region (Pérez-Maestro and Bueno-Ramírez 2022). Although these sites are a treasure, many analyses are still based on what is seen and interpreted, lacking organized color data, which complicates the comparison of data and the reconstruction of the area’s color palettes.

In recent years, advancements in non-destructive technologies have made it possible to enhance the way colors are documented, with a notable emphasis on the use of mobile spectrophotometers, colorimeters, and standardized recording systems, such as the Natural Color System (NCS) or the Munsell Color Chart (Pastilha et al. 2019; Ramírez Barat et al. 2021). These tools have been employed in heritage spaces to preserve visible colors without affecting the paintings. However, several authors have pointed out significant technical issues, for example systems like NCS display color through limited examples and do not cover the entire visible spectrum (Pastilha et al. 2019; León-Castellanos et al. 2010).

Studies such as those by Sepúlveda et al. (2013) in northern Chile and González-Sanz et al. (2022) in Spain have already demonstrated how the deterioration of paintings, the appearance of crusts, or changes in the surface complicate color measurement, especially where colors are less intense. This compels us to be very cautious when analyzing color data in rock art. In Peru, although progress is being made in the use of more precise archaeometric techniques, such as portable X-ray fluorescence, Raman spectroscopy, or scanning electron microscopy with energy dispersive spectroscopy, standardized documentation of color is still in its infancy, particularly in remote locations like Ccorca.

In this work, we explore how colors vary in the rock paintings of Tecsecocha, in Ccorca (Cusco). To achieve this, we used a portable spectrophotometer, the XRite Capsure™, and the NCS color coding system. We recorded six scenes featuring animals, human figures, and symbols, following a non-invasive method to protect the heritage. We analyzed which tones predominate and discussed the utility of the data we obtained, taking into account the accuracy of the device and the color model used.

Nestled in the Ccorca district, within the province and region of Cusco, the Tecsecocha area stands out as one of the most significant and best-preserved groups of rock art in the southern Andes of Peru (See Figure 1). Located about 21 kilometers west of the city of Cusco (see Figure 1), in a terrain characterized by rugged relief and geological structures of reddish layers known as “red layers”, this site is distinguished by its cliffs and rock shelters that have served as a canvas for paintings of great historical, artistic, and symbolic importance (Barreda-Murillo 1995; Hostnig 2021).

The pictorial expressions of Tecsecocha are primarily found on the rocky cliffs of the Maraskay canyon, in the area that locals refer to as Intiyoq Wayq’o (canyon of the Sun). These paintings are believed to date back to ancient pre-Hispanic times, possibly from the Late Preceramic period to the Middle Horizon, although their exact dating still requires confirmation through methods such as radiocarbon dating or Raman spectroscopy (Barreda-Murillo 1995; Flórez-Delgado 2004).

The rock art site in Tecsecocha consists of panels featuring representations of animals, people, and geometric shapes. Notably, there are many images of Andean camelids, circles within circles, simplified human figures, and symbols that may allude to ritual or ceremonial sites (Hostnig 2024). The painting technique employed involves the use of mineral pigments applied directly onto the rock. It is common to observe one layer of paint over another, suggesting that the painting area was used multiple times or that it was given new meaning over time (see Figure 2).

In Tecsecocha, the most prominent colors are red, ochre, white, and to a lesser extent, yellow. This is logical, as these minerals are available in the region. Initial research, based on visual observation and digital color analysis (NCS), reveals tones where red is particularly striking against yellowish bases, with variations that could be attributed to the original materials or surface deterioration (Villar-Quintana 2022; Pérez-Maestro and Bueno-Ramírez 2022).

The site of Tecsecocha, located in an east-facing ravine not far from ancient pre-Hispanic routes connected to the Qhapaq Ñan (Inca Royal Road), suggests that this location played an important role within a context of rituals and pathways. It may have served as a point for marking territories, for the contemplation of celestial bodies, or for purposes related to fertility and the agricultural calendar (Carreño-Collatupa 2020; Hostnig 2024).

Despite its significance, the rock art found at Tecsecocha has not been thoroughly studied using technical and analytical methodologies. Most existing documents come from research based on visual inspection, photographs taken on site, and descriptive sketches (Barreda-Murillo 1995; Hostnig 2021). It is essential to implement non-invasive procedures for chromatic and material analysis, such as spectrophotometry, to advance the interpretation of the pictorial tones and their symbolic meaning in the Andean world.

The primary objective is to promote a research path that still requires further exploration in the Peruvian Andean region: the comprehensive description of color present in rock art. This description is conceived not merely as a method of recording but as a key element for the technical and symbolic study, as well as the confrontation of these ancient visual manifestations.

2. Results

This analysis focused on all the rock panels identified in the Tecsecocha area, which belongs to the Ccorca district in Cusco, Peru. In total, six rocky walls with rock art were located and recorded, representing the complete set that can currently be seen and accessed at this archaeological site. These walls are situated along the cliffs of Maraskay, on outcrops of reddish sandstone.

Each of the six panels displays figures of animals, people, or geometric shapes. The decision to examine all accessible walls is based on both a desire to complete the documentation at a manageable scale and the appropriate size of the site, which facilitates a comprehensive analysis without jeopardizing the preservation of the heritage. Therefore, the research does not employ sampling but examines the entirety of the painted panels that have been found at the site to date.

In total, 153 readings were taken across the six panels, providing a reference information base to define color variation in the rock art manifestations of the area (see

Table 1. NCS tone register in rock paintings.

Scene	Element	# of Record	NCS Tone	Predominant Tone
Family of camelids and concentric circles	Female camelid	1	S 3005-Y20R	S 3005-Y20R
		2	S 2005-Y20R
		3	S 3005-Y20R
	Male camelid	4	S 1015-Y10R	S 1515-Y10R
		5	S 1515-Y10R
		6	S 1515-Y10R
	Camelid offspring	7	S 1515-Y10R	S 1515-Y10R
		8	S 1515-Y10R
		9	S 1515-Y10R
	Exterior rim	10	S 0505-Y80R	S 0505-Y80R
		11	S 0505-Y80R
		12	S 1005-Y80R
	Intermediate ring	13	S 4020-Y70R	S 4020-Y70R
		14	S 3020-Y70R
		15	S 4020-Y70R
	Inner circle	16	S 0507-Y60R	S 0507-Y60R
		17	S 0507-Y60R
		18	S 0505-Y60R
Four-leaf clover	Light leaves	19	S 0505-Y80R	S 0505-Y80R
		20	S 0505-Y80R
		21	S 0505-Y80R
	Dark leaves	22	S 3020-Y60R	S 320-Y60R
		23	S 3020-Y60R
		24	S 2020-Y60R
Solar	Light stripes	25	S 3010-Y50R	S 3020-Y80R
		26	S 2010-Y50R
		27	S 3010-Y50R
	Dark stripes	28	S 2020-Y60R	S 3020-Y60R
		29	S 3020-Y60R
		30	S 3020-Y60R
Solitary camelid	Camelid	31	S 2010-Y50R	S 2010-Y50R
		32	S 1010-Y50R
		33	S 2010-Y50R
Pair of camelids and human silhouette	turned camelid	34	S 2030-Y70R	S 2030-Y70R
		35	S 1030-Y70R
		36	S 2030-Y70R
	Horizontal camelid	37	S 3010-Y40R	S 3010-Y40R
		38	S 3010-Y40R
		39	S 3010-Y40R
	Human silhouette	40	S 3010-Y40R	S 3010-Y40R
		41	S 3010-Y40R
		42	S 3010-Y40R
Three humans	Human left	43	S 3040-Y30R	S 3040-Y30R
		44	S 3040-Y30R
		45	S 2040-Y30R
	Central human	46	S 3040-Y30R	S 3040-Y30R
		47	S 3040-Y30R
		48	S 3040-Y30R
	Right human	49	S 3040Y30R	S 3040Y30R
		50	S 3040Y30R
		51	S 3040Y30R

).

Scene 1: A family group of camelids and expanding circles

In this representation, elements of animals (a mother camelid, her offspring, and a male camelid) are combined with a geometric design of circles that share the same center. Upon studying the colors, it was discovered that the predominant tone in the animals was S3005-Y20R (a yellow with low reddish tones of 20%), while the farthest circle displayed the tone S0505-Y80R, a white. The band between the two showed S4020-Y70R, and the central white was similar to S0507-Y60R. The scene appears to be a thoughtfully composed arrangement, where the contrast between red and white accentuates the symbolic importance of the area depicted (see Figure 3).

The numbering present in the figures corresponds to the points recorded with the colorimeter, with 3 repetitions of measurements for each element in the scenes to ensure greater accuracy of the prevailing tone.

Scene 2: A four-leaf clover

Located one meter off the ground, this geometric shape has been considered a possible symbol related to fertility or the way rituals were organized at the site. Color measurement revealed two main tones, S0505-Y80R (lighter leaves) and S3020-Y60R (darker leaves), both derived from warm tones with a significant presence of red. The way the pigment was applied in layers highlights the symmetry of the design, and its position on the panel suggests strategic visibility from the outside (see Figure 4).

Similarly, the range of recorded numbers from (19-21) corresponds to the points recorded with the colorimeter on the scene and observed tones.

Scene 3: Solar Representation

In this section, a 50 cm circle is highlighted, radiating lines reminiscent of the sun, flanked on both sides by four clear marks. The shades S3010-Y50R and S3020-Y60R were used, mixtures of yellow with a hint of red that enhance the image. Although the surface is somewhat damaged by cracks in the stone, the image remains recognizable. This recurring design in other areas of the southern Andes suggests that it may have a ritual significance related to the sun (Hostnig 2024) (see Figure 5).

The range of recorded numbers from (25–30) corresponds to the points recorded with the colorimeter on the scene and observed tones.

Scene 4: Isolated Camelid

The central image here is painted in the shade S2010-Y50R, a yellow with a slight reddish tint. The color helps to highlight the silhouette of the animal, next to which a person is depicted simply, with one arm raised. The way they are positioned and the direction they are facing suggests a visual narrative of interaction between people and animals, perhaps related to hunting or herding (see Figure 6).

The range of recorded numbers from (31–33) corresponds to the points recorded with the colorimeter on the scene and observed tones.

Scene 5: A pair of camelids next to a human silhouette.

Here, we observe the colors S2030-Y70R (for the standing camelid) and S3010-Y40R (for the lying camelid and the person). The color contrast between them appears intentional, perhaps to indicate differences in importance or roles (such as mother and child). The design effectively reflects the shape of the animals and plays with color intensity to separate the figures from the stone environment (see Figure 7).

The range of recorded numbers from (34–42) corresponds to the points recorded with the colorimeter on the scene and observed tones.

Scene 6: Three representations of people.

The three human figures are depicted in motion, with arms and legs extended, suggesting they may be walking or dancing. The primary color used is S3040-Y30R, a cheerful yellow with a hint of red, applied with straight lines that contribute to the sense of movement. The fact that all three share the same color suggests that the same paint was used, likely finely ground hematite (see Figure 8).

The range of recorded numbers from (43–51) corresponds to the points recorded with the colorimeter on the scene and observed tones.

In all the analyzed scenes, a clear predominance of the hue between yellow (Y) and yellow–red (YR) is evident, particularly in tones such as Y30R, Y50R, and Y60R. This chromatic concentration indicates a repeated use of warm shades that range from yellowish and reddish ochres, visually associated with the colors of the earth and the surrounding natural environment. The choice of these hues suggests a certain visual intentionality in harmonizing the figures with the rocky support and the landscape (see Figure 9).

The chromatic triangles show that the selected hues are not located at the corners of highest clarity or darkness in the NCS system but rather in intermediate positions. This indicates that the scenes exhibit medium brightness and low saturation, meaning earthy colors that are not very contrasting against the stony background. This visual characteristic could relate to a strategy of chromatic discretion or integration with the environment, but it may also respond to processes of aging of perceptual color.

Despite the thematic diversity (zoomorphic, anthropomorphic, and geometric figures), the color selection remains consistent in most scenes. The repeated predominance of tones such as Y30R and Y50R reveals a deliberate tonal consistency, which could be understood as part of a visual system shared among the creators of the rock art. The reiteration of the warm spectrum suggests a chromatic identity specific to the site, distinguishable from other rock art contexts that exhibit a greater tonal variety.

In some specific representations, such as the anthropomorphic figures in the lower row, the color points approach lighter areas of the NCS (natural color system) triangle, indicating brighter tones, possibly with a greater presence of visual white or with less darkness. This perceptible variation adds contrast within the same scene, enhancing the legibility of the figures and contributing to the compositional dynamism.

Circular diagrams visually reinforce the tonal concentration within the Y–YR quadrant of the NCS color circle. This form of representation allows for precise identification of the predominant hue in each scene, highlighting that cool tones (such as blue, green, or violet) and pure neutral tones (such as perceptual white, gray, or black) were not used. This bias towards warm hues contributes to a uniform visual reading of the pictorial ensemble and suggests a cohesive chromatic identity at the site (see Figure 10).

3. Discussion

The use of the Capsure spectrophotometer provides a chromatic approach based on reflectometric readings in the visible spectrum (400–700 nm), without achieving a complete chemical characterization of the pigments. This limitation, previously noted by Pastilha et al. (2019) and León-Castellanos et al. (2010), implies that the measurements obtained are subject to factors such as the texture and porosity of the rocky substrate, the presence of patinas, surface degradation, and alterations due to environmental exposure and carbonate coasts or biological colonization (González-Sanz et al. 2022). Despite these limitations, the use of the NCS (natural color system), which, although criticized for representing color through a finite sample of predefined shades, allows for standardized coding that is useful for making comparisons with other sites and future research.

The results of the study indicate a predominance of red and white tones, with a range of variation primarily expressed in shades of red (S2030-Y70R yellow with 70% red, S3010-Y40R yellow with 40% red, and S3005-Y20R yellow with 20% red). The variability detected between anthropomorphic and zoomorphic figures suggests technical and symbolic differences in the preparation or application of the pigments. This distinction is likely associated with differentiated cultural meanings, as argued by Dupey García (2015), in which intense red is related to vitality, blood, or strength, while white may be linked to the spiritual or the ritual.

Although spectrophotometry does not replace archaeometric analysis, its application in Tecsecocha allows for mapping the color palette used and its distribution by motifs, which serves as a foundation for approaching the symbolism and techniques in Andean rock art. Additionally, encoding the tones using a standardized system (NCS) facilitates their comparison with other areas featuring Andean rock art and supports their digital preservation in heritage repositories.

From a broader perspective, the findings of this study contribute to the understanding of pictorial technology in the rock art of the Andean region. The application of the NCS (natural color system) has allowed for the identification of general patterns in the chromatic variability of paints; however, it is important to consider the inherent limitations of this system. As noted by Pastilha et al. (2019), the NCS, being a system based on discrete samples, represents only approximately 53% of the visible spectrum perceived by the human eye, which limits its ability to capture subtle nuances, especially in colors with low chromaticity. Therefore, while the NCS system enhances the standardized communication of color compared to systems like Munsell, the data obtained should be interpreted as an approximation that must be complemented with more precise spectroscopic methods. Research in other regions has indicated that the mineralogical composition of pigments directly influences their stability and resistance to degradation, which would explain the preservation of certain tones in the analyzed paintings (Cardoso 2020; Dupey García 2015).

Moreover, the spatial arrangement of the pictorial panels and the orientation of the figures suggest a relationship with the geographical environment and the structure of the ritual landscape. The scene of the four-leaf clover, located in an elevated area of the cliff and executed with S0505-Y80R and S3020-Y60R colors, reinforces the hypothesis that certain paintings were strategically placed to be visible from specific points, which could be related to ceremonial practices or territorial markings. This idea has been previously proposed in studies on rock art in the Loco River basin and in Pachacamac, where the superposition of pictorial elements with significant geological structures has been observed (Pérez-Maestro and Bueno-Ramírez 2022; Colonna-Preti and Eeckhout 2018).

Although this study has established a foundation for the chromatic characterization of rock art in Ccorca, there are still open questions that could be addressed in future research. Among them, the following stand out:

• The application of complementary techniques such as Raman spectroscopy or X-ray fluorescence would allow for the confirmation of the exact composition of the pigments and their possible geological origin.
• Evaluating the impact of environmental factors on the stability of the recorded tones would help understand the degradation processes and develop more effective preservation strategies.
• A comparative analysis of the color range in different areas of Cusco would allow for the identification of regional patterns in the use of color and the establishment of possible networks of cultural transmission in pictorial production.
• Previous research has suggested that some cave paintings might be related to astronomical alignments or seasonal cycles Domínguez-Bella and García Sanjuán (2025). An interdisciplinary study in this line could provide new insights into the meaning of certain representations.

Although colors such as the reddish and ochre tones observed in the study may be due to iron oxides or perhaps certain natural components (clays) that contain iron, we cannot assert that the readings obtained with a spectrophotometer alone can definitively indicate the chemical source of these hues. Authors such as Chaplin et al. (2016) and Chiappe et al. (2020) note that, to ascertain the elements and molecules that constitute the pigments, we need tools such as X-ray fluorescence, scanning electron microscopy with energy dispersive spectroscopy, or Fourier-transform infrared spectroscopy. However, these color approximations serve as a starting point for future research where these techniques can be applied to more thoroughly establish the chromatic origin of the pigments.

4. Materials and Methods

This research is situated within an exploratory and descriptive study aimed at detailing the diversity of colors observed in representations of rock art. To achieve this, a non-destructive methodology was chosen, relying on the use of portable colorimetry. The fundamental purpose was to document and compare the identifiable color values in the rock paintings located in the Tecsecocha area, which belongs to the Ccorca district in Cusco, Peru. This was carried out using a digital spectrophotometer, a device that operates within the visible spectrum, between 400 and 700 nanometers, and employs the color notation system known as the natural color system (NCS).

The study conducted colorimetric measurements of the cave paintings using the portable Capsure spectrophotometer from XRite, the CAPSURE 2.0 colorimeter is manufactured by X-Rite, Inc. (Grand Rapids, MI, USA), an American company specializing in color measurement and management solutions. X-Rite’s headquarters is located in Grand Rapids, Michigan, United States. which allows for samples to be obtained without physically altering the cave paintings. This equipment captures reflectance only within the visible range (400–700 nm) and interprets the data into codes from the NCS color notation system. It is important to clarify that this equipment does not obtain chemical composition data of the paints or the pigments used. While there is evidence regarding the low accuracy of this equipment for measuring irregular surfaces or for addressing aging pathologies, the current study provides visual approximations of the chromatic palette observed in the cave paintings at Tecsecocha.

The XRite Capsure™ 2.0 spectrophotometer was used, a portable device based on the spectral reflectance reading technique, which converts light signals into color values according to standardized colorimetry systems, specifically the NCS (natural color system). The Capsure incorporates a D65 light source and an 8 mm reading area, with internal automatic adjustment. Readings were taken from dry and stable areas, selecting zones without visible traces of organic materials, lichens, or dissolved salts. For each color in each element of the six recorded scenes, three consecutive readings were taken to achieve an average that minimizes the device’s deviation. The NCS data were cross-referenced on-site with the physical reference guide to ensure consistency between the detected color and its official nomenclature.

The natural color system (NCS) is a method of recording color based on how we perceive it, utilizing the psychophysics of color. This system describes each color as a mixture of four basic colors that our mind recognizes, white, black, yellow, and red. This allows us to discuss color in a subjective yet effective manner. It has proven to be very useful in heritage conservation, as it helps standardize how we describe the colors we see in archaeological sites and works of art.

However, studies such as those by Pastilha et al. (2019) and León-Castellanos et al. (2010) have pointed out that the NCS, like the Munsell system, does not view color as a continuous measure of radiation but rather as a limited set of samples. This can reduce the accuracy and reproducibility of the recorded values, especially in materials with little color or damaged surfaces.

Similarly, certain contrasting studies such as Bloch et al. (2021) have shown that the Capsure device exhibits limited accuracy in detecting subtle colors, demonstrating a noticeable difference compared to specialized visual assessment. For these reasons, the results obtained through this methodology should be understood as a referential approach aimed at the visual communication of color, rather than as an exact material or spectral characterization of the pigment. The absence of complementary analyses using Raman spectroscopy, X-ray fluorescence (XRF), or infrared spectroscopy (FTIR) prevents the precise determination of the elemental and molecular composition of the pigments.

The applied chromatic recording procedure was designed as a completely non-destructive technique, adhering to international standards for the documentation of archaeological heritage, without direct contact with the pigments or alteration of the intervened surfaces. Below is a detailed description of the operational sequence implemented to ensure the integrity of the rock art throughout the process.

• Initial Photographic Capture

Before any measurements were taken with instruments, high-quality photographs were captured of each of the six selected locations. A digital single-lens reflex camera with an APS-C sensor and a standard 50 mm lens was used, ensuring minimal visual alteration. The images were saved in RAW format to preserve the color data intact. The photographs were taken using soft natural light, avoiding reflections or direct light to prevent affecting color interpretation. Each location was photographed from a distance of about 50 to 100 cm, depending on the size of the panel, maintaining a right angle with the surface of the rock to reduce visual distortions.

• Colorimetric Recording with Capsure™ 2.0 Spectrophotometer

For each of the figures appearing in the six scenes (whether human figures, animals, or geometric shapes), areas were selected that clearly displayed the color tone. Care was taken not to choose areas with pathologies (such as white spots, wear, moss, or black crusts), always seeking locations where the color appeared uniform and free of surface layers. At each of these selected points, three consecutive measurements were taken using the XRite Capsure™ 2.0 spectrophotometer. The measurements were conducted by placing the device directly against the surface (without applying pressure), following the manufacturer’s instructions for preparation. Each time a measurement was taken, the device automatically stored it and converted it to a natural color system (NCS) coordinate system. This provided information on the hue (W), the blackness (S), and the chromaticity of the color (C), along with a code consisting of numbers and letters. It was verified that these measurements matched the colors from the NCS atlas to ensure that what we observed was accurate.

• Data Download, Organization, and Processing

Once data collection at the site was completed, the information stored on the Capsure™ device was extracted using the “SpectraMagic NX” software developed by the manufacturer. Each measurement obtained was manually linked to its specific position and graphical representation, relying on a preliminary schematic of each environment.

The information was organized into a structured database in spreadsheet format (Excel), where the following was recorded for each point:

-

Scene and graphical representation

-

Anatomical or symbolic part

-

Complete NCS (natural color system) coordinates (T/C/M and code)

-

Reference images

-

Annotations taken on-site (preservation status, lighting, surface characteristics).

• The NCS (natural color system) data were illustrated in triangular diagrams of the NCS system.

This visualization revealed how colors are distributed in terms of hue (W), blackness (S), and chromaticity (C). This method of displaying the data made it easier to identify color groups and potential trends when selecting pigments or noticing differences due to climate. Additionally, bar graphs and color maps were created to observe how colors change between figures within the same scene and across different scenes. The tonal variations among the records were compared with previous studies on Andean rock art, raising ideas about the symbolism of color, the materials available, and whether there were similar methods of working across regions.

• Conservation and Precautions

Care was taken to ensure that the method used is non-invasive. Direct or indirect lighting was avoided, no wet substances or adhesives were added, and the scanner was handled gently, without aggressive mechanical contact with the surface of the painting.

• Comparison of records: Considering that the NCS (natural color system) relies on a limited set of reference examples, its utility for measuring color has its limitations, especially when dealing with colors that have changed or are not very intense. Research such as that by Pastilha et al. (2019) has highlighted that both the NCS and the Munsell system are not perfect for representing all colors continuously. Therefore, the NCS codes recorded in this research should be viewed as an approximate visualization of color in cave paintings.

5. Conclusions

Cusco has a rich tradition of rock painting, in which inorganic pigments extracted from natural quarries near archaeological sites were used. The motivations for the rock paintings vary; however, they coincide in the representation of daily life activities, such as hunting, agriculture among others, rituals, and religious beliefs, specific to each recorded human settlement.

The district of Ccorca in Cusco possesses one of the most recognizable examples of rock painting that was the subject of this research. The implementation of the NCS (natural color system) to record color helped organize and contrast the different shades present in the studied scenes. However, we understand that, by relying on specific examples, this system may not be perfect for identifying very subtle color changes or colors that gradually blend. For future studies, more precise spectral systems or devices that measure color over a wider range will be employed to obtain more comprehensive information.

There is a predominance of two-color ranges (whites and reds), varying between S2030-Y70R and S3010-Y40R, which indicates the presence of yellow tones with a 70% and 40% influence of red, respectively.

The comparison between the colors of the anthropomorphic figures painted in the cave paintings shows subtle differences in the influence of red and the overall hue. Both colors are moderately chromatic yellows, but they vary in the amount of red added to the mix. These differences suggest that the cave artists might have used different proportions of pigments to achieve certain visual or symbolic effects in their anthropomorphic representations. The variability in the influence of red could also indicate variations in cultural or technological practices in the preparation and application of pigments.

The variation observed in the colors of the camelid rock art figures reveals a significant range in yellow tones and the influence of red. The lighter and less chromatic colors (S3005-Y20R and S1515-Y10R) contrast with the more intense and warmer tones (S2030-Y70R), which show a high influence of red. This variability could indicate differences in the composition of the pigments used or in the application techniques.

The diversity of colors observed in the bicolor figures of the cave paintings reflects a variety in the use of yellow pigments with different percentages of red, which may have been influenced by cultural factors and pigment preparation techniques used in the paintings.

The research provided an initial insight into the study of color in rock art, thanks to a portable and non-invasive methodology that preserves the integrity of the artistic expressions in the study area; however, the contributions of Bloch et al. (2021) suggest that, to achieve definitive analyses of the materials, it would be essential to incorporate archaeometric methods that rely on spectroscopic and physicochemical techniques.