# eblurhash - Blurhash for Erlang

This is an Erlang version of https://blurha.sh

A _blurhash_ is a compact string with encoded colors to show a blurred version of an image before the image
itself is loaded.

## With ImageMagick

Use the `magick` function to first let imagemagick resize (and secure) the
image, before using the blurhash program to calculate the hash.

```erlang
eblurhash:magick("path/to/image.jpg").
```

Return something like:

```erlang
{ok, <<"MlMF%n00%#Mwo}S|WCWEM{a$R*bbWBbHfl">>}
```

**Note:** you will need to have ImageMagick installed

The `magick` command checks the image size and selects optimal X and Y size for the blurhash.
Where X and Y are in the range 1..5.

The command line program `convert` is used to convert the image to a smaller gif file.
This gif file is then provided to the `blurhash` program.

## Using `blurhash` directly

This uses the C version of blurhash on the supplied image file.

The C version uses `stb_image` to load images, which is not security-hardened, so it
is **not** recommended to use this version in production on untrusted data!

The blurhash command needs to have the X and Y arguments provided:

```erlang
eblurhash:hash(5, 3, "path/to/image.jpg").
```

Returns `{ok, <<"...">>}` or `{error, Reason}`.