VueCraft NPM

Encode Command ​

The hazehash command comes with the hazehash package. It needs the optional package sharp to read images:

bash
npm install --save-dev hazehash sharp
npx hazehash --help

Every command has its own --help with the full list of options. The global options are -h, --help, -V, --version and --color / --no-color. Colours are also off when the output is piped, when NO_COLOR is set and on a dumb terminal, and FORCE_COLOR turns them on. The other commands are on Decode and Info Commands.

encode ​

Creates hashes from image files, folders, globs or standard input. In a terminal the result is a coloured table with the size of each image, the size of its hash, the average colour and a summary; when the output is piped it is plain text, so scripts can use it as it is.

bash
hazehash encode <input…> [options]

An input is an image file, a folder, a glob such as "photos/**/*.jpg" (quote it so your shell does not expand it) or - to read one image from standard input.

Example — one image, printed alone:

bash
hazehash encode photo.jpg
text
Ed7UwRWKKv5znm6a7sC1tziHDNpMuCikxrYpIg

Example — a folder, as a table:

bash
hazehash encode ./images --pretty
text
HazeHash encode  budget 28 B · profile default · alpha auto

    Image                      Pixels      File  Hash  Value
  ✔ images/alpha-003.png     1280×510   43.4 KB  13 B  NYATKSAAADXSSaWLiA
  ✔ images/city-012.jpg      1280×959  280.6 KB  28 B  Ed7UwRWKKv5znm6a7sC1tziHDNpMuCikxrYpIg
  ✔ images/document-004.jpg  1280×821  508.7 KB  28 B  Et4TPyOAQNXnVbzFulUm5bq7tUi1isKm3pOziQ

✔ 3 hashes · 832.8 KB → 69 B · 12,359× smaller · 186 ms

The table above is the layout for 100 columns. A wider terminal also shows the average colour of each image, with a colour swatch, and how many times the hash is smaller than the file; a narrower one drops the less important columns first.

Hash options ​

-b, --budget <bytes> ​

The maximum size of one hash in bytes, header included. Default 28; the minimum is 7 bytes, or 9 with alpha. More bytes keep more detail; see Choosing a budget.

bash
hazehash encode photo.jpg --budget 24

-p, --profile <name> ​

How hard the encoder searches: fast (about 1 ms per image), default (about 5 ms) or high (refines the result for about 1% less error). Default default.

-a, --analysis-size <px> ​

The long side of the downscaled image the hash is computed from, 32–128. Default 64; larger rarely helps.

--alpha <mode> ​

auto stores transparency only when the image has some (the default), true always stores it, and false never does.

Which images ​

-r, --recursive ​

Also search sub-folders when an input is a folder. A glob with ** always does.

Output ​

-f, --format <kind> ​

text writes the hash alone for one image, or path<TAB>hash lines for several. json writes an object { "path": "hash" }. csv writes a table with a header row. Default text.

bash
hazehash encode ./images -f json
json
{
  "images/alpha-003.png": "NYATKSAAADXSSaWLiA",
  "images/city-012.jpg": "Ed7UwRWKKv5znm6a7sC1tziHDNpMuCikxrYpIg",
  "images/document-004.jpg": "Et4TPyOAQNXnVbzFulUm5bq7tUi1isKm3pOziQ"
}

--details ​

With json and csv, adds the size of the hash, the size of the image and the size of the file.

bash
hazehash encode ./images -f csv --details
text
file,hash,bytes,width,height,fileBytes
images/alpha-003.png,NYATKSAAADXSSaWLiA,13,1280,510,44406
images/city-012.jpg,Ed7UwRWKKv5znm6a7sC1tziHDNpMuCikxrYpIg,28,1280,959,287378
images/document-004.jpg,Et4TPyOAQNXnVbzFulUm5bq7tUi1isKm3pOziQ,28,1280,821,520957

--hex ​

Writes hashes as hex instead of base64url.

bash
hazehash encode photo.jpg --hex
# 11ded4c1158a2afe739e6e9aeec0b5b738870cda4cb828a4c6b62922

-o, --output <file> ​

Writes the result to a file instead of standard output.

bash
hazehash encode "images/**/*.jpg" -f json -o hashes.json

--pretty, --plain ​

--pretty is the coloured table with a summary, the default in a terminal. --plain is for scripts and the default when the output is piped.

-q, --quiet ​

No progress and no summary, only the result and the errors.

Reading from standard input ​

bash
cat photo.jpg | hazehash encode -

Exit codes ​

  • 0 — every image was encoded.
  • 1 — at least one input failed. The others are still written, and the failure is reported on standard error.
  • 2 — a mistake in the command line.

An input that is not found is reported like this:

text
✖ nothing.jpg: no image found