Struct img_hash::ImageHash

pub struct ImageHash {
    pub bitv: BitVec,
    pub hash_type: HashType,
}

A struct representing an image processed by a perceptual hash. For efficiency, does not retain a copy of the image data after hashing.

Get an instance with ImageHash::hash().

Fields

bitv: BitVec

The bits of the hash

hash_type: HashType

The type of the hash

Methods

impl ImageHash

pub fn hash<I: HashImage>(     img: &I,     hash_size: u32,     hash_type: HashType ) -> ImageHash

Create a hash of img with a length of hash_size * hash_size (* 2 when using HashType::DoubleGradient) using the hash algorithm described by hash_type.

pub fn dist(&self, other: &ImageHash) -> usize

Calculate the Hamming distance between this and other. Equivalent to counting the 1-bits of the XOR of the two BitVec.

Essential to determining the perceived difference between self and other.

###Panics If self and other have differing bitv lengths or hash_type values.

pub fn dist_ratio(&self, other: &ImageHash) -> f32

Calculate the Hamming distance between self and other, then normalize it to [0, 1], as a fraction of the total bits.

Roughly equivalent to the % difference between the two images, represented as a decimal.

See ImageHash::dist().

pub fn size(&self) -> u32

Get the hash size of this image. Should be equal to the number of bits in the hash.

pub fn hash_type(&self) -> HashType

Get the HashType that this ImageHash was created with.

Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn to_bytes(&self) -> Vec<u8>

Build a grayscale image using the bits of the hash, setting pixels to white (0xff) for 0 and black (0x00) for 1.

pub fn from_base64(encoded_hash: &str) -> Result<ImageHash, FromBase64Error>

Create an ImageHash instance from the given Base64-encoded string.

Note:

Not compatible with Base64-encoded strings created before HashType was added.

Does not preserve the internal value of HashType::UserDCT.

Errors:

Returns a FromBase64Error::InvalidBase64Length when trying to hash a zero-length string

pub fn to_base64(&self) -> String

Get a Base64 string representing the bits of this hash.

Mostly for printing convenience.

Trait Implementations

impl PartialEq for ImageHash

fn eq(&self, other: &ImageHash) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &ImageHash) -> bool

This method tests for !=.

impl Eq for ImageHash

impl Hash for ImageHash

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where     H: Hasher,

Feeds a slice of this type into the given [Hasher].

impl Debug for ImageHash

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Clone for ImageHash

fn clone(&self) -> ImageHash

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.