Computational analysis of the photograph of the artwork Watercolor Study in Ab Major No. 3 (AQC1087) [1] by Arnaud Quercy [2], according to IDS-CMP-2025 [3], on an image 1000 pixels on its longer side, on 2026-07-13. Each colour is located in the Munsell system and named according to the ISCC-NBS system (267 names, National Bureau of Standards, 1976). The image divides into 19 flat areas. The largest are light greenish gray (53%), purplish gray (10%) and brownish gray (8.9%). Among the others, those that stand out most sharply from their surroundings are black at the bottom left (0.1%), purplish black in the centre (1.6%) and very dark reddish purple at the bottom (3.3%). By colour name family: gray 64%, blue 12%, brown 8.0%, olive gray 3.3%, reddish purple 2.7%, purple 2.6%, orange 2.4%, black 1.9%, red 1.2% and olive 1.1%.
Context
Analysis performed according to IDS-CMP-2025 [3]: (a) colours named by Munsell and ISCC-NBS, areas and flat areas, (b) texture, (c) brightness and contrast, (d) spatial distribution. Source image: 1592x2122 pixels. Analysis date: 2026-07-13.
A) Color Analysis
Flat areas
Ranked by contrast with their surroundings (CIEDE2000). Strokes thinner than 10 pixels are excluded (3).
| Rank |
Colour |
ISCC-NBS name |
Munsell |
Area |
Contrast |
Position |
| 1 |
060707 |
black |
N 0.1/ |
0.1% |
57.4 |
at the bottom left |
| 2 |
110F12 |
purplish black |
9.5P 0.4/0.6 |
1.6% |
46.5 |
in the centre |
| 3 |
44123D |
very dark reddish purple |
2.3RP 1.6/6.3 |
3.3% |
45.3 |
at the bottom |
| 4 |
9E6B48 |
light brown |
5.0YR 4.9/5.0 |
1.8% |
31.7 |
at the top |
| 5 |
3E4254 |
dark grayish blue |
5.0PB 2.8/2.1 |
1.0% |
29.2 |
in the centre |
| 6 |
A05124 |
strong brown |
3.1YR 4.4/8.8 |
1.1% |
27.8 |
at the top |
| 7 |
8C3512 |
strong reddish brown |
1.3YR 3.4/9.1 |
1.8% |
27.7 |
on the right |
| 8 |
0E0506 |
black |
0.6YR 0.1/0.3 |
0.7% |
27.0 |
at the bottom |
| 9 |
ADB4B4 |
light greenish gray |
9.4BG 7.2/0.6 |
53% |
24.0 |
in the centre |
| 10 |
9F869E |
pale purple |
7.6P 5.7/4.0 |
2.5% |
22.2 |
at the top left |
| 11 |
8F3914 |
strong brown |
2.3YR 3.5/8.7 |
3.2% |
21.9 |
at the bottom right |
| 12 |
382620 |
dark grayish reddish brown |
9.0R 1.7/2.0 |
0.1% |
21.4 |
at the top |
| 13 |
8A6755 |
light reddish brown |
2.4YR 4.5/3.6 |
2.1% |
20.9 |
in the centre |
| 14 |
C3B2AE |
pinkish gray |
3.4YR 7.4/1.4 |
0.7% |
17.1 |
in the centre |
| 15 |
423D38 |
dark reddish gray |
6.2R 2.6/0.6 |
0.3% |
12.1 |
at the bottom |
| 16 |
999CA0 |
purplish gray |
9.1PB 6.4/1.3 |
10% |
10.4 |
in the centre |
| 17 |
82899A |
pale blue |
5.4PB 5.7/2.6 |
5.8% |
8.7 |
in the centre |
| 18 |
4F4839 |
grayish olive |
0.5GY 3.1/1.5 |
0.2% |
8.0 |
at the bottom right |
| 19 |
6C675F |
brownish gray |
10.0YR 4.2/0.9 |
8.9% |
6.5 |
at the bottom right |
Colour name families
| Family |
Area |
| gray |
64% |
| blue |
12% |
| brown |
8.0% |
| olive gray |
3.3% |
| reddish purple |
2.7% |
| purple |
2.6% |
| orange |
2.4% |
| black |
1.9% |
| red |
1.2% |
| olive |
1.1% |
B) Texture Analysis
| Metric |
Value |
| Global Roughness |
0.179 |
| Mean Local Roughness |
0.018 |
| Roughness Uniformity |
0.017 |
| Edge Density |
0.024 |
| Mean Gradient Magnitude |
0.142 |
| Gradient Variance |
0.044 |
| Gradient Smoothness |
0.0 |
| Directional Coherence |
0.005 |
| Pattern Complexity |
0.133 |
| Pattern Repetition |
1.0 |
| Detail Frequency Ratio |
0.602 |
| Spatial Variation |
0.108 |
| Texture Consistency |
0.628 |
C) Brightness & Contrast Analysis
| Metric |
Value |
| Mean Brightness |
0.573 |
| Brightness Variance |
0.179 |
| Brightness Uniformity |
0.688 |
| Brightness Skewness |
-1.27 |
| Brightness Entropy |
6.941 |
| Rms Contrast |
0.179 |
| Michelson Contrast |
1.0 |
| Weber Contrast |
0.581 |
| Mean Local Contrast |
0.019 |
| Contrast Uniformity |
0.025 |
| Dynamic Range |
1.0 |
| Effective Dynamic Range |
0.573 |
| Shadow Percentage |
11.764 |
| Midtone Percentage |
43.083 |
| Highlight Percentage |
45.153 |
| Shadow Clipping |
0.04 |
| Highlight Clipping |
0.0 |
| Tonal Balance |
0.0 |
| Fine Contrast |
0.011 |
| Medium Contrast |
0.024 |
| Coarse Contrast |
0.037 |
| Multiscale Contrast Ratio |
0.307 |
| Edge Contrast |
0.142 |
| Contrast Clustering |
0.372 |
D) Spatial Distribution Analysis
| Metric |
Value |
| Spatial Coherence |
0.731 |
| Color Clustering |
0.729 |
| Color Transition Smoothness |
0.637 |
| Transition Uniformity |
0.676 |
| Sharp Transition Ratio |
0.1 |
| Transition Directionality |
0.005 |
| Mean Saturation |
0.167 |
| Saturation Variance |
0.059 |
| Low Saturation Ratio |
0.845 |
| Medium Saturation Ratio |
0.069 |
| High Saturation Ratio |
0.086 |
| Saturation Clustering |
0.998 |
| Hue Concentration |
0.643 |
| Complementary Balance |
0.031 |
| Analogous Dominance |
0.66 |
| Temperature Bias |
0.712 |
Methodology
Computational analysis of a photograph of the artwork, reduced to 1,000 pixels on its longer side and filtered by a 3×3 median to remove grain. Colours: each pixel (sRGB rounded to 5 bits per channel) receives its Munsell notation and ISCC-NBS name from a table computed once from published data (Munsell renotation; ISCC-NBS blocks, NBS Special Publication 440, 1976), never from the artworks. Flat areas: connected regions of one name, merged with their neighbours while the CIEDE2000 difference between their mean colours stays below 10; an area is kept from 0.05% of the image; contrast with the surroundings measured 4 to 12 pixels from the edge. Texture: intensity standard deviation, local standard deviation, edge density (Canny), local binary patterns. Brightness: mean, variance, RMS, Michelson and local contrast, shadow / midtone / highlight distribution. Distribution: spatial coherence, transitions, saturation. Methods are deterministic and reproducible. Limits: the measurement concerns the photograph, including its lighting and white balance; two neighbouring areas less than 10 apart are merged.
