Module hashers 

Built-in perceptual hash implementations.

This module provides various hash algorithms for duplicate frame detection:

• DHasher: Difference hash - fast, good for near-duplicates
• PHasher: Perceptual hash (DCT) - robust to transformations
• BlockHasher: Block average hash - balanced approach

All hashers implement the FrameHasher trait and can be used interchangeably.

Choosing a Hasher

Algorithm	Speed	Robustness	Best For
dHash	Fast	Moderate	Frame-to-frame comparison
pHash	Slow	High	Content matching across transforms
BlockHash	Medium	Medium	General purpose

For GIF frame analysis, dHash is recommended as the default due to its speed and effectiveness for detecting consecutive duplicate frames.

Structs

BlockHasher

Block hash for perceptual image comparison.

DHasher

Difference hash (dHash) for fast duplicate detection.

ImageHash

Re-export the ImageHash type from img_hash for convenience. A struct representing an image processed by a perceptual hash. For efficiency, does not retain a copy of the image data after hashing.

PHasher

Perceptual hash (pHash) using Discrete Cosine Transform.