Vix 
Vix is Elixir extension for vips image processing library.
Why Vix
Vix is a NIF based bindings library for libvips. Vix does not spawn OS processes for the operations like other libraries. And it can make full use of libvips optimizations such as joining of operations, cache etc.
Image Operation binding are generated using vips introspection, so documentation and bindings always matches the vips version installed.
Check vips operation documentation for the list of available operations and spec.
What is Vips
(from vips documentation)
libvips is a demand-driven, horizontally threaded image processing library. Compared to similar libraries, libvips runs quickly and uses little memory.
See libvips documentation for more details.
Introduction
Easiest way to get started with Vix, or to explore the operations is to use load Introduction Notebook using Livebook.
Available Notebooks:
Example
# print vips version
IO.puts("Version: " <> Vix.Vips.version())
# contains image read/write functions
alias Vix.Vips.Image
# reading image from a file. Note that image is not actually loaded to the memory at this point.
# img is `%Image{}` struct.
{:ok, img} = Image.new_from_file("~/Downloads/kitty.png")
# writing `Image` to a file.
# Image type selected based on the image path extension. See documentation for more options
:ok = Image.write_to_file(img, "kitty.jpg[Q=90]")
# let's print image dimensions
IO.puts("Width: #{Image.width(img)}")
IO.puts("Height: #{Image.height(img)}")
# Operations
# contains image processing operations
alias Vix.Vips.Operation
# getting a rectangular region from the image (crop)
{:ok, extract_img} = Operation.extract_area(img, 100, 50, 200, 200)
# create image thumbnail.
# this function accepts many optional parameters, see: https://libvips.github.io/libvips/API/current/Using-vipsthumbnail.md.html
# also see `Operation.thumbnail/3` which accepts image path
{:ok, thumb} = Operation.thumbnail_image(img, 100)
# resize image to 400x600. `resize` function accepts scaling factor.
# Skip `vscale` if you want to preserve aspect ratio
hscale = 400 / Image.width(img)
vscale = 600 / Image.height(img)
{:ok, resized_img} = Operation.resize(img, hscale, vscale: vscale)
# flip image
{:ok, flipped_img} = Operation.flip(img, :VIPS_DIRECTION_HORIZONTAL)
# Gaussian blur
{:ok, blurred_img} = Operation.gaussblur(img, 5)
# convert image to a grayscale image
{:ok, bw_img} = Operation.colourspace(img, :VIPS_INTERPRETATION_B_W)
# adding gray border
{:ok, extended_img} =
Operation.embed(img, 10, 10, Image.width(img) + 20, Image.height(img) + 20,
extend: :VIPS_EXTEND_BACKGROUND,
background: [128]
)
# rotate image 90 degree clockwise
{:ok, rotated_img} = Operation.rot(img, :VIPS_ANGLE_D90)
# join two images horizontally
{:ok, main_img} = Image.new_from_file("~/Downloads/kitten.svg")
{:ok, joined_img} = Operation.join(img, main_img, :VIPS_DIRECTION_HORIZONTAL, expand: true)
# render text as image
# see https://libvips.github.io/libvips/API/current/libvips-create.html#vips-text for more details
{:ok, {text, _}} = Operation.text(~s(<b>Vix</b> is <span foreground="red">awesome!</span>), dpi: 300, rgba: true)
# add text to an image
{:ok, img_with_text} = Operation.composite2(img, text, :VIPS_BLEND_MODE_OVER, x: 50, y: 20)
The libvips reference manual has more detailed documentation about the operations.
Warning
This library is experimental. Interface might change significantly in the future versions. The code is not well tested, so you might experience crashes.
Requirements
- libvips
- pkg-config
- c compiler
Installation
def deps do
[
{:vix, "~> x.x.x"}
]
end
TODO
- [ ] support mutable operations such as draw*
- [ ] support all remaining vips types