calculation of the 'dhash' of an image

Source: R/hash_functions.R

This function calculates the dhash of an image

dhash(gray_image, hash_size = 8, MODE = "hash", resize = "nearest")

Arguments

gray_image

a (2-dimensional) matrix or data frame

hash_size

an integer specifying the hash size (should be less than number of rows or columns of the gray_image)

MODE

one of 'hash' (returns the hash of the image), 'binary' (returns binary identifier of the image)

resize

corresponds to one of 'nearest', 'bilinear'

Value

either a hash-string or a binary vector

Details

The function is a modification of the 'dhash' function of the imagehash package [ please consult the COPYRIGHT file ]. In comparison to average_hash and phash, the dhash algorithm takes into consideration the difference between adjacent pixels.

Examples


image = readImage(system.file("tmp_images", "3.jpeg", package = "OpenImageR"))

image = rgb_2gray(image)

res_hash = dhash(image, hash_size = 8, MODE = 'hash')

res_binary = dhash(image, hash_size = 8, MODE = 'binary')