How To: Combine Detectors with CompositeDetector

When no single detector captures all colonies reliably, combine multiple detectors using CompositeDetector. It merges their results via union, intersection, or overlap.

from phenotypic.data import load_yeast_plate
from phenotypic.enhance import GaussianBlur, CLAHE
from phenotypic.detect import OtsuDetector, HysteresisDetector, CompositeDetector

plate = load_yeast_plate()
plate = GaussianBlur(sigma=2.0).apply(plate)
plate = CLAHE(clip_limit=0.01).apply(plate)

Union Mode

Keeps any pixel detected by any detector. Maximizes recall at the cost of potential false positives.

composite = CompositeDetector(
    detectors=[OtsuDetector(), HysteresisDetector(low="mean", high="otsu")],
    mode="union",
)
result = composite.apply(plate.copy())
print(f"Union: {result.num_objects} colonies")
result.dash(overlay=True)

Union: 7 colonies

Data type cannot be displayed: application/vnd.plotly.v1+json

Intersection Mode

Keeps only pixels detected by all detectors. Maximizes precision.

composite_intersect = CompositeDetector(
    detectors=[OtsuDetector(), HysteresisDetector(low="mean", high="otsu")],
    mode="intersection",
)
result2 = composite_intersect.apply(plate.copy())
print(f"Intersection: {result2.num_objects} colonies")
result2.dash(overlay=True)

Intersection: 9 colonies

Data type cannot be displayed: application/vnd.plotly.v1+json

Choose union to catch faint colonies, intersection for high-confidence detection, or overlap with a minimum overlap ratio for a middle ground.