src/palette/quantizer.py

from sklearn.cluster import KMeans
from .color_space import rgb_to_lab, lab_to_rgb

LARGE_DATASET_THRESHOLD = 10000
KMEANS_INIT_ATTEMPTS_FOR_LARGE_DATA = 3
KMEANS_INIT_ATTEMPTS_FOR_SMALL_DATA = 10
KMEANS_MAX_ITERATIONS_LARGE_DATA = 100
KMEANS_MAX_ITERATIONS_SMALL_DATA = 300
RANDOM_SEED = 42


def quantize_colors(colors, target_color_count=256):
    if len(colors) == 0:
        raise ValueError("No colors to quantize")

    perceptual_colors = rgb_to_lab(colors)
    total_input_colors = len(perceptual_colors)

    kmeans_config = determine_kmeans_parameters(total_input_colors)
    actual_clusters = min(target_color_count, total_input_colors)

    print(
        f"Quantizing {total_input_colors} colors to {target_color_count} palette entries..."
    )

    cluster_model = KMeans(
        n_clusters=actual_clusters,
        n_init=kmeans_config["init_attempts"],
        max_iter=kmeans_config["max_iterations"],
        random_state=RANDOM_SEED,
    )
    cluster_model.fit(perceptual_colors)

    palette_centers_in_lab = cluster_model.cluster_centers_
    palette_in_rgb = lab_to_rgb(palette_centers_in_lab)

    print(f"Created palette with {len(palette_in_rgb)} unique colors")
    return palette_in_rgb


def determine_kmeans_parameters(sample_count):
    if sample_count >= LARGE_DATASET_THRESHOLD:
        return {
            "init_attempts": KMEANS_INIT_ATTEMPTS_FOR_LARGE_DATA,
            "max_iterations": KMEANS_MAX_ITERATIONS_LARGE_DATA,
        }
    else:
        return {
            "init_attempts": KMEANS_INIT_ATTEMPTS_FOR_SMALL_DATA,
            "max_iterations": KMEANS_MAX_ITERATIONS_SMALL_DATA,
        }