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Table 1
Definition of the EFIGI morphological attributes grouped by attribute type.
| Attribute type / name | Attribute definition |
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| Bulge | |
| B/T | Ratio of bulge luminosity over total galaxy luminosity |
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| Spiral arms | |
| Arm Strength | Strength of the spiral arms, in terms of flux fraction relative to the whole galaxy |
| Arm Curvature | Average curvature of the spiral arms |
| Arm Rotation | Winding of the spiral pattern (0–1 for clockwise, 2 for no preferred direction, 3–4 for counterclockwise) |
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| Dynamical features | |
| Bar Length | Length of central bar component |
| Inner Ring | Strength of inner ring, inner lens or inner pseudo-ring (located inside the disk and/or spiral arm pattern and near the end of the bar) |
| Outer Ring | Strength of outer ring (located outside the disk and/or spiral arm pattern) |
| Pseudo-Ring | Type and strength of outer pseudo-rings  ,  and  |
| Perturbation | Deviation of the light distribution from a profile with rotational symmetry |
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| Texture | |
| Visible Dust | Strength of features tracing the presence of dust: obscuration and/or diffusion of star light by a dust lane or molecular clouds |
| Dust Dispersion | Patchiness of the dust distribution (smooth and sharp lanes or strongly irregular patches) |
| Flocculence | Flocculent aspect of the galaxy due to scattered HII regions |
| Hot Spots | Strength of regions with very high surface brightness, including giant regions of star formation, active nuclei, or stellar nuclei |
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| Appearance | |
| Inclination- Elongation | For disk galaxies, inclination f = 1 − cosθ, where θ is the angle between the rotation axis of the disk and the light-of-sight of the observer, or equivalently between the galaxy disk and the plane of the sky (0° for face-on, 90° for edge-on) |
| For spheroidal galaxies, apparent elongation of the object f = 1 − b/a (where a and b are the apparent major and minor axis lengths). | |
| Arm Rotation | see above, in “Spiral arms” attribute type |
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| Environment | |
| Contamination | Severity of the contamination by bright stars, overlapping galaxies or image artifacts (diffraction spikes, star halos, satellite trails, electronic defects) |
| Multiplicity | Abundance of neighbouring galaxies differing by less than ~ 5 mag from the main galaxy and centred within 0.75 D25 from its centre |
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