kirz_blurry_image_detector 2.0.0

Blurry image detector plugin

kirz_blurry_image_detector

One-pass iOS photo library analyzer for cleaner apps: finds blurry photos and computes perceptual hashes for duplicate detection in a single native sweep with a shared persistent cache.

How it works

The native side (Swift + Metal) walks the photo library once. For every image it fetches a small 128×128 pixel buffer and computes:

• Sharpness score — variance of the Laplacian (LoG) on gamma luma, evaluated on a 3×3 tile grid and scored by the sharpest tile, so bokeh portraits, night shots and minimalist compositions aren't falsely flagged. GPU-accelerated via MetalPerformanceShaders, batched in one command buffer per 64 images.
• 64-bit dHash — perceptual hash robust to re-compression, resizing and format conversion; two copies of the same photo differ by only a few bits.

Both values are cached persistently per asset id. Re-scans only analyze new photos; the cache survives app restarts, is saved incrementally during the scan (a killed scan resumes where it left off), and prunes deleted assets. Degraded thumbnails (e.g. iCloud-offloaded originals with only a low-res preview available) are never scored — they're retried on a later scan instead of producing false verdicts.

Usage

import 'package:kirz_blurry_image_detector/kirz_blurry_image_detector.dart';

// Blurry photo ids. Score < threshold == blurry; scores are cached, so
// changing the threshold does NOT trigger a re-scan.
final blurryIds = await BlurryImageDetector.findBlurryImages(
  threshold: 0.02, // default
  onProgress: (processed, total) => print('$processed / $total'),
);

// Perceptual hashes for duplicate grouping (same scan & cache — if
// findBlurryImages already ran, this returns instantly).
final hashes = await BlurryImageDetector.getImageHashes();
// => { assetLocalIdentifier: 64-bit dHash as int }

Group duplicates by Hamming distance on the returned hashes (e.g. union-find with a distance threshold of ~4 bits for strict duplicates).

Requirements

• iOS 11+ (MetalPerformanceShaders), photo library permission granted.
• Asset ids are PHAsset.localIdentifier — the same ids used by photo_manager's AssetEntity.id.

Notes

• iOS only. Android is not supported.
• findBlurryImages and getImageHashes serialize internally: calling both concurrently performs a single scan.