Test images¶
20 grayscale 2D images for testing and benchmarking orientation analysis: 8 synthetic, whose orientation is known by construction, 4 compositions of rings, ramp and noise at four levels of degradation, the test image of the structure vs nematic assessment, and 8 real images. Each image comes with a binary mask of its meaningful structures, and with an overview panel of the results.
The test-images folder of the repository holds the 20 source images in images/, the 20 binary masks in masks/, and in code/ what builds them: synthetic_images_2D.ipynb generates the synthetic images and the compositions, masks_2D.ipynb the masks (the gradient energy above 0.5% of its maximum, or the analytic annulus for the compositions), and macro-maps.ijm computes with the plugin the feature maps of every image (orientation, coherency, energy, 32-bit TIFF). Below, every image comes with an overview panel: original, mask, orientation, coherency, energy, color survey, masked distribution and vector field, all computed at the plugin defaults (cubic-spline gradient, σ = 1). The images are listed in the order of the montage; click a panel for full size.
Real images¶
cell_aemisegger 
¶
728 × 728, uint8, values in [0, 252] — real: fluorescence cell, actin fibers.
collagen ¶
512 × 512, uint8, values in [2, 255] — real: collagen fibers.
dendrochronology ¶
512 × 512, uint8, values in [0, 255] — real: wood section, growth rings.
fibronectin_arafat_plos2025 ¶
1024 × 1024, uint8, values in [0, 255] — real: fibronectin network (Arafat et al., PLOS ONE 2025).
M. Arafat et al., PLOS ONE (2025), doi:10.1371/journal.pone.0320006.
fibrous_tissues_fibero2024 ¶
2048 × 2048, uint16, values in [87, 4094] — real: fibrous tissue (FiberO, 2024).
FiberO dataset (2024), doi:10.3389/fbioe.2024.1497837.
fiji_directionality_montage ¶
1536 × 1536, uint16, values in [3089, 65535] — real: montage from the Fiji Directionality documentation.
Montage from the documentation of the Fiji Directionality plugin.
nanofiber_fiji_diameterj ¶
512 × 512, uint8, values in [0, 255] — real: SEM nanofibers (DiameterJ sample).
DiameterJ sample — S. A. Hotaling et al., Data in Brief (2015), doi:10.1016/j.dib.2015.07.012.
polymer_slice_quanfima2018 ¶
600 × 600, float32, values in [−0.0029, 0.0030] — real: polymer slice (quanfima, 2018).
Synthetic images¶
synthetic_bundles_512 
¶
512 × 512, float32, values in [0, 1] — synthetic: matted web of 4000 wavy fibers rendered as lit tubes of radius 0.1–3 px, knitted by branching, with three elliptical patches that pull the fibers into bundles.
synthetic_chirp_1024 ¶
1024 × 1024, float32, values in [0, 1] — synthetic: radial chirp with a frequency sweep; the tangential ground-truth orientation is known at every pixel.
synthetic_filaments_512 ¶
512 × 512, float32, values in [0, 1] — synthetic: random curved filaments.
synthetic_nematic_512 ¶
512 × 512, float32, values in [0, 1] — synthetic: nematic-like texture with a dominant direction.
Pattern inspired by active nematics — A. Doostmohammadi, J. Ignés-Mullol, J. M. Yeomans, F. Sagués, Active nematics, Nature Communications 9:3246 (2018), doi:10.1038/s41467-018-05666-8.
synthetic_noise_512 ¶
512 × 512, float32, values in [0, 1] — synthetic: isotropic noise; any measured anisotropy is bias.
synthetic_rings_dither_512 ¶
512 × 512, float32, values in [0, 1] — synthetic: thin concentric rings with a small dither (σ = 10⁻⁴) that avoids degenerate-tensor spikes; exact tangential truth.
synthetic_spiral_512 ¶
512 × 512, float32, values in [0, 1] — synthetic: spiral.
synthetic_wave_512 ¶
512 × 512, float32, values in [0, 1] — synthetic: three waves with fringes at exactly 5°, 45° and 85° and periods of 2, 8 and 64 px, plus uniform noise, in a circular Tukey window of 480 px.
Compositions: rings, ramp and noise at four levels of degradation¶
composition_rings_degraded_none_384 
¶
384 × 384, float32, values in [0, 1] — composition: clean sine rings of period 20 px on an annulus of radii 70–175 px with smooth edges; no saturation, no ramp, no noise: the reference level of the structure vs nematic assessment. Exact tangential truth; the mask is the annulus.
composition_rings_degraded_low_384 ¶
384 × 384, float32, values in [0, 1] — composition: the same rings, 40% of the pixels saturated (clipped), on a vertical ramp of slope 0.01 per px, plus Gaussian noise of σ = 0.005; the low level of the structure vs nematic assessment.
composition_rings_degraded_medium_384 ¶
384 × 384, float32, values in [0, 1] — composition: the same rings, 60% of the pixels saturated, ramp of slope 0.02 per px, Gaussian noise of σ = 0.015; the medium level of the structure vs nematic assessment.
composition_rings_degraded_high_384 ¶
384 × 384, float32, values in [0, 1] — composition: the same rings, 80% of the pixels saturated, ramp of slope 0.05 per px, Gaussian noise of σ = 0.025; the high level of the structure vs nematic assessment.
