yduf / dhash

Fast perceptual image hash

Difference Hash computation

Licensed under the GNU General Public License, version 3. (GPLv3)

Based on idea from article / 2

Behavior

• try to keep aspect ratio when computing hash
• use one of these 3 ratio that fit into 64bits: 8x8, 9x7, 10x6
• rotate image by 90 when needed, to always fit into these ratios.
• use libvips thumbnail for fast reduction
• image formats are those supported by libvips
• output results a one line json for easier script integration

Compiling

Install dependencies:

• libvips

meson build .
cd build
meson compile

Usage

$ dhash ~/Pictures/*.webp
{"file":"/home/yves/Pictures/6ihqil3250u91.webp","hash":4413131122559126504,"height":7,"rot90":1,"width":9}