blockhash

README

blockhash-go

Go implementation of blockhash, a perceptual hash of images

See godoc.org for documentation.

Reference implementation

Install

go get "github.com/haochi/blockhash-go"

Test Images

Test images are in public domain and I found them on https://pixabay.com

Documentation

Overview

Go implementation of blockhash (http://blockhash.io), a perceptual hash of images

Reference implementation: https://github.com/commonsmachinery/blockhash-python/tree/0d76144cf5b6ac149ff7612ab433a48b0fb9139b

Index

• type Hash
  • func Blockhash(reader io.Reader, bits int) (*Hash, error)
  • func (hash *Hash) ToHex() string

Examples

• Blockhash

Types

type Hash

type Hash struct {
	// bit representation of the hash
	Bits []int
}

func Blockhash

func Blockhash(reader io.Reader, bits int) (*Hash, error)

Generates the block hash for a given image `bits` should be a power of 2 number (e.g. 2, 4, 8, 16, etc.); the number of output bits is equal to bits^2

Example

reader, err := os.Open(defaultFile) // Get the file reader for the image
if err != nil {
	log.Fatal(err)
}
hash, _ := Blockhash(reader, 16)    // Divide the image into 16x16 blocks, and calculate the hash
fmt.Println("Bits", hash.Bits[:32]) // You should use the entire content in `Bits` though
fmt.Println("Hex", hash.ToHex())

Output:

Bits [1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 1 1 1 0 0 0 0 0 0 1 1 0 0 0]
Hex 801e3818fd80ffecfffc0ffc0e38000899ff193c1d38083c5c6c9e781e310fb0

func (*Hash) ToHex

func (hash *Hash) ToHex() string

A string representation of the hash in hex format