smartdownsample 0.4.0

Smart image downsampling for image classification datasets

smartdownsample

Fast, simple image downsampling that just works

SmartDownsample samples diverse images from large collections in seconds, not hours. One simple function that works equally fast whether you're sampling 100 or 23,000 images from 24,000.

Installation

pip install smartdownsample

Features

• ⚡ Always fast - Seconds for any selection ratio
• 🎯 Smart bucketing - Better than random, faster than complex algorithms
• 📊 Scales linearly - 24k images? No problem
• 🔧 Dead simple - One function, always works
• 🎲 Reproducible - Set seed for consistent results

Usage

from smartdownsample import sample_diverse

# Sample 100 diverse images from 24,000 - takes seconds
selected = sample_diverse(
    image_paths=my_24k_images,
    target_count=100
)

# Sample 23,000 images from 24,000 - also takes seconds!
selected = sample_diverse(
    image_paths=my_24k_images,
    target_count=23000
)

# It's that simple.
print(f"Sampled {len(selected)} diverse images")

How It Works

1. Hash images - Quick perceptual hashing (4 parallel workers)
2. Create buckets - Group similar images together
3. Sample evenly - Take images from each bucket for diversity

Result: Better than random selection, without the complexity.

Performance

Task	Time
100 from 1,000	<5 sec
900 from 1,000	<5 sec
1,000 from 24,000	~30 sec
23,000 from 24,000	~30 sec
Any ratio	Fast ✓

Parameters

Parameter	Default	Description
image_paths	Required	List of image file paths (str or Path objects)
target_count	Required	Exact number of images to select
n_workers	4	Number of parallel workers (4 is optimal)
hash_size	8	Hash size (8 is fast and good enough)
random_seed	42	Random seed for reproducible results
show_progress	True	Whether to display progress bars

Why It's Fast

• Fixed algorithm - No switching between methods
• Simple hashing - DHash is faster than PHash
• Smart bucketing - O(n) grouping instead of O(n²) comparisons
• Parallel processing - But capped at 4 workers (diminishing returns above that)

License

MIT License – see LICENSE file.