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evision
| OS | Arch | ABI | Build Status | Has Precompiled Library |
|---|---|---|---|---|
| Linux | x86_64 | gnu |  | Yes |
| Linux | x86_64 | musl |  | Yes |
| Linux | arm64 | gnu |  | Yes |
| Linux | arm64 | musl | | Yes |
| Linux | armv7l (armhf) | gnueabihf | | Yes |
| Linux | ppc64le | gnu | | Yes |
| Linux | s390x | gnu | | Yes |
| Linux | riscv64 | gnu | | Yes |
| Linux | riscv64 | musl | | Yes |
| macOS 11 Big Sur | x86_64 | darwin |  | Yes |
| macOS 11 Big Sur | arm64 | darwin |  | Yes |
| Windows 2022 | x86_64 | msvc |  | Yes |
Docs
Online docs for the latest released version is available on Hex.pm, https://hexdocs.pm/evision/.
Nerves Support
[](https://github.com/cocoa-xu/evision)
Prebuilt firmwares are available [here](https://github.com/cocoa-xu/evision/actions/workflows/nerves-build.yml?query=is%3Asuccess).
Select the most recent run and scroll down to the `Artifacts` section, download the firmware file for your board and run
```bash
fwup /path/to/the/downloaded/firmware.fw
```
In the nerves build, `evision` is integrated as one of the dependencies of the [nerves_livebook](https://github.com/livebook-dev/nerves_livebook)
project. This means that you can use livebook (as well as other pre-pulled libraries) to explore and evaluate the `evision`
project.
The default password of the livebook is `nerves` (as the time of writing, if it does not work, please check the nerves_livebook project).
For Nerves users only, please also check the [EVISION_ENABLE_CONTRIB](https://github.com/cocoa-xu/evision#evision_enable_contrib) section for important messages.
## Register Builtin Smart Cells
```elixir
# List all smart cells
smartcells = Evision.SmartCell.available_smartcells()
# register all smart cells
Evision.SmartCell.register_smartcells(smartcells)
# you can also register a subset of these smart cells
# e.g., only register the Model Zoo smart cell
Evision.SmartCell.register_smartcells(Evision.SmartCell.Zoo)
```
Integration with Nx
```elixir
iex> mat = Evision.imread("/path/to/image.png")
%Evision.Mat{
channels: 3,
dims: 2,
type: {:u, 8},
raw_type: 16,
shape: {512, 512, 3},
ref: #Reference<0.2992585850.4173463580.172624>
}
iex> t = Evision.Mat.to_nx(mat)
#Nx.Tensor<
u8[512][512][3]
Evision.Backend
[
[
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, 255],
[255, 255, ...],
...
],
...
]
>
```
and vice-versa:
```elixir
iex> %Evision.Mat{} = mat = Evision.imread("/path/to/image.png")
iex> t = Evision.Mat.to_nx(mat)
# convert a tensor to a mat
iex> mat_from_tensor = Evision.Mat.from_nx(t)
%Evision.Mat{
channels: 1,
dims: 3,
type: {:u, 8},
raw_type: 0,
shape: {512, 512, 3},
ref: #Reference<0.1086574232.1510342676.18186>
}
# Note that `Evision.Mat.from_nx` gives a tensor
# however, some OpenCV functions expect the mat
# to be a "valid 2D image"
# therefore, in such cases `Evision.Mat.from_nx_2d`
# should be used instead
#
# Noticing the changes in `channels`, `dims` and `raw_type`
iex> mat_from_tensor = Evision.Mat.from_nx_2d(t)
%Evision.Mat{
channels: 3,
dims: 2,
type: {:u, 8},
raw_type: 16,
shape: {512, 512, 3},
ref: #Reference<0.1086574232.1510342676.18187>
}
# and it works for tensors with any shapes
iex> t = Nx.iota({2, 3, 2, 3, 2, 3}, type: :s32)
iex> mat = Evision.Mat.from_nx(t)
%Evision.Mat{
channels: 1,
dims: 6,
type: {:s, 32},
raw_type: 4,
shape: {2, 3, 2, 3, 2, 3},
ref: #Reference<0.1086574232.1510342676.18188>
}
```
#### Unsupported Type Map
As OpenCV does not support the following types (yet, as of OpenCV 4.8.0)
- `{:s, 64}`
- `{:u, 32}`
- `{:u, 64}`
Although it's possible to *store* values with those types using custom types, the resulting Mat/tensor will be incompatible with most existing functions in OpenCV.
Moreover, it's somewhat inconvinient to explicitly specify the type each time using them. Therefore, Evision allows to set a map for those unsupported types.
```elixir
config :evision, unsupported_type_map: %{
{:s, 64} => {:f, 64},
{:u, 64} => {:f, 64},
{:u, 32} => {:f, 32}
}
```
The `key` of this `unsupported_type_map` is the unsupported type, and the value is the replacement type for it.
See [this reply](https://github.com/cocoa-xu/evision/issues/48#issuecomment-1266282345) for more details on this.
Access behaviour (Getting a sub-area of an image)
- `Access.fetch/2` examples:
```elixir
iex> img = Evision.imread("test/qr_detector_test.png")
%Evision.Mat{
channels: 3,
dims: 2,
type: {:u, 8},
raw_type: 16,
shape: {300, 300, 3},
ref: #Reference<0.809884129.802291734.78316>
}
# Same behaviour as Nx.
# Also, img[0] gives the same result as img[[0]]
# For this example, they are both equvilent of img[[0, :all, :all]]
iex> img[[0]]
%Evision.Mat{
channels: 3,
dims: 2,
type: {:u, 8},
raw_type: 16,
shape: {1, 300, 3},
ref: #Reference<0.809884129.802291731.77296>
}
# same as img[[0..100, 50..200, :all]]
# however, currently we only support ranges with step size 1
#
# **IMPORTANT NOTE**
#
# also, please note that we are using Elixir.Range here
# and Elixir.Range is **inclusive**, i.e, [start, end]
# while cv::Range `{integer(), integer()}` is `[start, end)`
# the difference can be observed in the `shape` field
iex> img[[0..100, 50..200]]
%Evision.Mat{
channels: 3,
dims: 2,
type: {:u, 8},
raw_type: 16,
shape: {101, 151, 3},
ref: #Reference<0.809884129.802291731.77297>
}
iex> img[[{0, 100}, {50, 200}]]
%Evision.Mat{
channels: 3,
dims: 2,
type: {:u, 8},
raw_type: 16,
shape: {100, 150, 3},
ref: #Reference<0.809884129.802291731.77297>
}
# for this example, the result is the same as `Evision.extractChannel(img, 0)`
iex> img[[:all, :all, 0]]
%Evision.Mat{
channels: 1,
dims: 2,
type: {:u, 8},
raw_type: 0,
shape: {300, 300},
ref: #Reference<0.809884129.802291731.77298>
}
iex> img[[:all, :all, 0..1]]
%Evision.Mat{
channels: 2,
dims: 2,
type: {:u, 8},
raw_type: 8,
shape: {300, 300, 2},
ref: #Reference<0.809884129.802291731.77299>
}
# when index is out of bounds
iex> img[[:all, :all, 42]]
{:error, "index 42 is out of bounds for axis 2 with size 3"}
# it works the same way for any dimensional Evision.Mat
iex> mat = Evision.Mat.ones({10, 10, 10, 10, 10}, :u8)
iex> mat[[1..7, :all, 2..6, 3..9, :all]]
%Evision.Mat{
channels: 1,
dims: 5,
type: {:u, 8},
raw_type: 0,
shape: {7, 10, 5, 7, 10},
ref: #Reference<0.3015448455.3766878228.259075>
}
```
- `Access.get_and_update/3` examples:
```elixir
iex> mat = Evision.Mat.zeros({5, 5}, :u8)
iex> Evision.Nx.to_nx(mat)
#Nx.Tensor<
u8[5][5]
Evision.Backend
[
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 0]
]
>
iex> {old, new} = Evision.Mat.get_and_update(mat, [1..3, 1..3], fn roi ->
{roi, Nx.broadcast(Nx.tensor(255, type: roi.type), roi.shape)}
end)
iex> Evision.Nx.to_nx(new)
#Nx.Tensor<
u8[5][5]
Evision.Backend
[
[0, 0, 0, 0, 0],
[0, 255, 255, 255, 0],
[0, 255, 255, 255, 0],
[0, 255, 255, 255, 0],
[0, 0, 0, 0, 0]
]
>
```
Examples
Some examples are available in the examples directory.
Description
evision will pull OpenCV source code from GitHub, then parse and automatically generate corresponding OpenCV-Elixir bindings.
This project uses and modifies gen2.py and hdr_parser.py from the python module in the OpenCV repo so that they output header files that can be used in Elixir bindings.
We hope this project can largely reduce the work of manually porting OpenCV functions/modules to Elixir.
Compatible OpenCV versions:
- 4.5.3
- 4.5.4
- 4.5.5
- 4.6.0
- 4.7.0
- 4.8.0
by compatible, it means these versions can compile successfully, and I tested a small range of functions. Tons of tests should be written, and then we can have a list for tested OpenCV versions.
Installation
In order to use evision, you will need Elixir installed. Then create an Elixir project via the mix build tool:
$ mix new my_app
Then you can add evision as dependency in your mix.exs.
def deps do
[
{:evision, "~> 0.1"}
]
endPlease note that although :evision is available on hex.pm now, it's still in its early versions. And it will remain on v0.1.x for a while, and all v0.1.x versions should be treated as in very active development. Please read the CHANGELOG.md for all breaking changes even it's a "minor" update.
Therefore, it's recommended to use a specific version (i.e., include the minor version number in deps, {:evision, "~> 0.1.8"}, instead of {:evision, "~> 0.1"}) at the moment.
Use Precompiled Library (Default)
The following environment variables can be set based on your needs.
(Note that precompiled binaries do not use FFmpeg. If you'd like to use FFmpeg, please compile from source (please see instructions in the next section) and set corresponding environment variables. We're considering this option at the moment.)
Important notes
It is recommended to use :evision from hex.pm.
def deps do
[
{:evision, "~> 0.1"}
]
endTARGET_ABI
Required if and only if the target is using musl libc.
# (for nerves project, this environment variable is set by nerves)
export TARGET_ABI=musl
## (for armv7l which uses hard-float ABI (armhf))
export TARGET_ABI=musleabihf
This variable will only be checked when identifying the musl libc ABI so that the correct precompiled binaries can be downloaded. Therefore,
- You don't need to keep it in the runtime environment.
- If you want to change it later, the directory
_build/${MIX_ENV}/lib/evisionneeds to be deleted first.
The default value for the TARGET_ABI env var is obtained using the following elixir code
target_abi = List.last(String.split(to_string(:erlang.system_info(:system_architecture)), "-"))
target_abi =
case target_abi do
"darwin" <> _ -> "darwin"
"win32" ->
{compiler_id, _} = :erlang.system_info(:c_compiler_used)
case compiler_id do
:msc -> "msvc"
_ -> to_string(compiler_id)
end
_ -> target_abi
endEVISION_PREFER_PRECOMPILED
# optional.
# set this to "false" if you prefer :evision to be compiled from source
#
# default value is "true", and :evision will prefer to use precompiled binaries (if available)
export EVISION_PREFER_PRECOMPILED=false
This variable will only be checked whenever the mix compile task is invoked directly (mix compile) or indirectly (mix test). And in the Makefile we would skip everything if _build/${MIX_ENV}/lib/evision/priv/evision.so is presented. Therefore,
- You don't need to keep it in the runtime environment.
- If you want to change it later, the directory
_build/${MIX_ENV}/lib/evisionneeds to be deleted first.
If you found the precompiled binaries do not suit your needs (e.g., perhaps you need OpenCV to be compiled with FFmpeg to handle more video formats.), it's possible to override the behaviour by setting the environment variable EVISION_PREFER_PRECOMPILED to false, and then please delete _build/${MIX_ENV}/lib/evision and recompile evision
Also, for Linux users only, the precompiled binary is not compiled with GTK support, therefore functions like Evision.HighGui.imshow/2 will not work. However, you can either use Evision.Wx.imshow/2 (if Erlang on your system is compiled with wxWidgets), or set the environment variable EVISION_PREFER_PRECOMPILED to false so that OpenCV can detect available HighGui backend when compiling from source.
export EVISION_PREFER_PRECOMPILED=false
For livebook users,
Mix.install([
{:evision, "~> 0.1"}
], system_env: [
{"EVISION_PREFER_PRECOMPILED", "false"}
])EVISION_ENABLE_CONTRIB
Set environment variable EVISION_ENABLE_CONTRIB to true to enable modules from opencv_contrib.
# enable opencv_contrib modules (default)
export EVISION_ENABLE_CONTRIB=true
# disable opencv_contrib modules
export EVISION_ENABLE_CONTRIB=false
This variable will only be checked whenever the mix compile task is invoked directly (mix compile) or indirectly (mix test). And in the Makefile we would skip everything if _build/${MIX_ENV}/lib/evision/priv/evision.so is presented. Therefore,
- You don't need to keep it in the runtime environment.
- If you want to change it later from
falsetotrue, you can delete the file_build/${MIX_ENV}/lib/evision/priv/evision.so, setEVISION_ENABLE_CONTRIBtotrue, and then executemix compile.
Defaults to true because for precompiled binaries, including these "extra" modules only increases less than 20 MBs (tested on aarch64-apple-darwin) in size.
However, 20 MBs for Nerves users can be a huge deal (still depending on your device, for example, +20 MBs is often much more acceptable for RPIs as they are usually equipped with >= 8 GB microSD cards while being absolutely a luxury thing for some other embedded devices).
EVISION_ENABLE_CUDA
Set environment variable EVISION_ENABLE_CONTRIB to true to enable CUDA support from opencv_contrib. Defaults to false.
Note that EVISION_ENABLE_CONTRIB will need to be true as well.
# enable CUDA support
export EVISION_ENABLE_CUDA=true
## set a CUDA version that matches your local CUDA driver
## (this environment variable is only required for users who'd like to use precompiled binaries)
## available ones are
## 111, for CUDA 11.1.x, built with CUDA 11.1.1
## 114, for CUDA 11.4.x, built with CUDA 11.4.3
## 118, for CUDA 11.8.x, built with CUDA 11.8.0
export EVISION_CUDA_VERSION=118
## opencv_contrib modules is enabled by default
export EVISION_ENABLE_CONTRIB=true
# disable CUDA support (default)
export EVISION_ENABLE_CUDA=false
IMPORTANT NOTE FOR WINDOWS USERS
If EVISION_ENABLE_CUDA is true, please also set CUDA runtime dir otherwise Evision will fail to load.
cmd
set EVISION_CUDA_RUNTIME_DIR=C:/PATH/TO/YOUR/CUDA/RUNTIME/BINAlso, please don't quote even if there are spaces in the path
set EVISION_CUDA_RUNTIME_DIR=C:/PATH WITH SPACE/TO/YOUR/CUDA/RUNTIME/BINPowershell
$Env:EVISION_CUDA_RUNTIME_DIR="C:/PATH/TO/YOUR/CUDA/RUNTIME/BIN"
$Env:EVISION_CUDA_RUNTIME_DIR="C:/PATH WITH SPACE/TO/YOUR/CUDA/RUNTIME/BIN"EVISION_PRECOMPILED_CACHE_DIR
# optional.
## set the cache directory for the precompiled archive file
export EVISION_PRECOMPILED_CACHE_DIR="$(pwd)/.cache"
Compile evision from source
#### Dependencies
- Python3 (Only during the compilation, to generate binding files)
- 3.8.12
- 3.9.9
- 3.10.1
- [CMake](https://cmake.org/) >= 3.3 (for this project)
The minimal version required by OpenCV can vary between versions.
OpenCV 4.5.5 requires at least CMake 3.5.1.
- Erlang development library/headers. Tested on OTP/25.
#### Build from source
To obtain and compile OpenCV's source code from official releases, the following environment variables can affect the build
```shell
# optional
## set OpenCV version
## the corresponding license file should be available at https://github.com/opencv/opencv/blob/${OPENCV_VER}/LICENSE
export OPENCV_VER="4.8.0"
# optional
## Use Debug build
export CMAKE_BUILD_TYPE=Debug
# optional
## enable FFmpeg
## this will allow cmake to auto-detect FFmpeg libraries installed on the host
## on Windows, OpenCV will download prebuilt FFmpeg libraries
## for more information, please visit https://github.com/opencv/opencv/tree/4.x/3rdparty/ffmpeg
export CMAKE_OPENCV_OPTIONS="-D WITH_FFMPEG=ON"
## or disable FFmpeg
export CMAKE_OPENCV_OPTIONS="-D WITH_FFMPEG=OFF"
```
Note 1: OpenCV can encode and decode some video formats (varies depending on your system). FFmpeg can be used to encode/decode more video formats.
However, you should be aware of the license of the FFmpeg components you selected as they could be licensed by LGPL/GPL or other licenses.
Note 2: Installing FFmpeg
On DEBIAN/Ubuntu
```shell
sudo apt install -y libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libavresample-dev ffmpeg
```
on macOS
```shell
# FFmpeg 4
brew install ffmpeg@4
brew link ffmpeg@4
# FFmpeg 5
brew install ffmpeg
brew link ffmpeg
```
##### Extra notes for building from source on Windows
Evision on Windows uses `nmake` to handle the `Makefile.win` at the moment. And we also need `powershell` for now. `nmake`
should be included in Microsoft Visual Studio, and `powershell` should be included in almost all recent versions (it was
first released in 2007) of Windows.
If `ninja` can be found in `%PATH%`, then we will prefer using `ninja` to build everything as it allows parallel building.
Evision is NOT tested in MSYS2, Cygwin, or WSL/WSL2.
#### Using source from a git repo (Optional)
It's also possible to obtain and compile OpenCV's source code from a custom git repo by setting the following environment variables (in addition to the ones above)
```shell
# required if and only if you prefer to compile OpenCV from a git repo
# set OPENCV_USE_GIT_HEAD to true to compile OpenCV from a git repo
# default value is false
export OPENCV_USE_GIT_HEAD=true
# required if and only if you prefer to compile OpenCV from a git repo
# this env var indicates which branch you prefer to use
# no default value
export OPENCV_USE_GIT_BRANCH=4.x
# optional.
# set this env var to specify which git repo to use
# default value is https://github.com/opencv/opencv.git, which is the official git repo of OpenCV
export OPENCV_GIT_REPO="https://github.com/opencv/opencv.git"
```
When `OPENCV_USE_GIT_HEAD` is set to `true`, the following command will be used to fetch OpenCV's source code in `Makefile`:
```shell
git clone --branch=${OPENCV_USE_GIT_BRANCH} --depth=1 ${OPENCV_GIT_REPO} "${OPENCV_DIR}"
```
#### More Configuration (Optional)
`evision` will compile a subset of OpenCV functionality. You can configure the enabled modules in your `config` files:
```elixir
config :evision, enabled_modules: [
:calib3d,
:core,
:features2d,
:flann,
:highgui,
:imgcodecs,
:imgproc,
:ml,
:photo,
:stitching,
:ts,
:video,
:videoio,
:dnn
]
```
If a module is not specified in `:enabled_modules`, it may still be compiled if all requirements are present in your machine.
You can enforce only the `:enabled_modules` to be compiled by changing the compilation mode:
```elixir
config :evision, :compile_mode, :only_enabled_modules
```
You can also configure the list of image codecs used:
```elixir
config :evision, enabled_img_codecs: [
:png,
:jpeg,
:tiff,
:webp,
:openjpeg,
:jasper,
:openexr
]
```
#### Notes
- How do I use my own OpenCV source code on my local disk?
```shell
# To skip the download process, you can put the source zip file at `3rd_party/cache/opencv-${OPENCV_VER}.zip`.
# Or you could supply OpenCV source code at `3rd_party/opencv/opencv-${OPENCV_VER}`.
#
# `3rd_party/opencv/opencv-${OPENCV_VER}` is the default value for `OPENCV_DIR`
export OPENCV_DIR=/path/to/your/opencv/source/root
```
- How do I use my own OpenCV source code on my git repo?
```shell
# use branch
export OPENCV_USE_GIT_BRANCH="branch_name"
export OPENCV_GIT_REPO="https://github.com/username/opencv.git"
# use HEAD
export OPENCV_USE_GIT_HEAD=true
export OPENCV_GIT_REPO="https://github.com/username/opencv.git"
```
- How do I set the number of jobs for compiling?
```shell
# use all logical cores, by default
# `"-j#{System.schedulers_online()}"`. In `mix.exs`.
export MAKE_BUILD_FLAGS="-j$(nproc)"
# use 2 cores
export MAKE_BUILD_FLAGS="-j2"
```
- How do I set up for cross-compile or specify the toolchain?
```shell
export CMAKE_TOOLCHAIN_FILE="/path/to/toolchain.cmake"
```
- How do I make my own adjustments to the OpenCV CMake options?
```shell
export CMAKE_OPENCV_OPTIONS="YOUR CMAKE OPTIONS FOR OPENCV"
```
- How do I generate binding code for erlang and Elixir at the same time?
Yes, but currently it's only possible to do so when compiling evision using `mix`.
```shell
# default value is `elixir` when compiling evision using `mix`
# default value is `erlang` when compiling evision using `rebar`
#
# expected format is a comma-separated string
export EVISION_GENERATE_LANG="erlang,elixir"
```
- Which ones of OpenCV options are supposed to be specified in `config/config.exs`?
1. Enabled and disabled OpenCV modules
2. Image codecs (if you enabled related OpenCV modules).
#### Debug related
Say you have the following MIX environment variables:
```shell
# set by MIX
MIX_ENV=dev
# set by evision or you
OPENCV_VER=4.8.0
# set by yourself if you're compiling evision to a nerves firmware
MIX_TARGET=rpi4
```
- How do I delete OpenCV related CMake build caches?
```shell
# delete OpenCV related CMake build caches.
rm -rf "_build/${MIX_ENV}/lib/evision/cmake_opencv_${OPENCV_VER}"
## for nerves
rm -rf "_build/${MIX_TARGET}_${MIX_ENV}/lib/evision/cmake_opencv_${OPENCV_VER}"
```
- How do I remove downloaded OpenCV source zip file.
```shell
rm -f "3rd_party/cache/opencv-${OPENCV_VER}"
```
- Can I manually edit the generated files and compile them?
1. First, delete evision.so (so that `cmake` can rebuild it)
```shell
#
rm -f "_build/${MIX_ENV}/lib/evision/priv/evision.so"
## if you're building with nerves,
## use this path instead
rm -rf "_build/${MIX_TARGET}_${MIX_ENV}/lib/evision/priv/evision.so"
```
2. Secondly, comment out the following lines in the CMakeLists.txt
otherwise, your editing will be overwritten by the `py_src/gen2.py` (executing from the `CMakeLists.txt`)
```cmake
if(WIN32)
execute_process(COMMAND "rmdir ${GENERATED_ELIXIR_SRC_DIR} /s /q && rmdir ${GENERATED_ERLANG_SRC_DIR} /s /q && mkdir ${GENERATED_ELIXIR_SRC_DIR} && mkdir ${GENERATED_ERLANG_SRC_DIR}")
message("enabled modules: ${ENABLED_CV_MODULES}")
execute_process(COMMAND python3.exe "${PY_SRC}\\gen2.py" "${C_SRC}" "${GENERATED_ELIXIR_SRC_DIR}" "${GENERATED_ERLANG_SRC_DIR}" "${C_SRC}\\headers.txt" "${EVISION_GENERATE_LANG}" "${ENABLED_CV_MODULES}" RESULT_VARIABLE STATUS)
else()
execute_process(COMMAND bash -c "rm -rf ${GENERATED_ELIXIR_SRC_DIR} && rm -rf ${GENERATED_ERLANG_SRC_DIR} && mkdir -p ${GENERATED_ELIXIR_SRC_DIR} && mkdir -p ${GENERATED_ERLANG_SRC_DIR}")
message("enabled modules: ${ENABLED_CV_MODULES}")
execute_process(COMMAND bash -c "python3 ${PY_SRC}/gen2.py ${C_SRC} ${GENERATED_ELIXIR_SRC_DIR} ${GENERATED_ERLANG_SRC_DIR} ${C_SRC}/headers.txt ${EVISION_GENERATE_LANG} ${ENABLED_CV_MODULES}" RESULT_VARIABLE STATUS)
endif()
if(STATUS STREQUAL "0")
message(STATUS "Successfully generated binding code for: ${EVISION_GENERATE_LANG}")
else()
message(FATAL_ERROR "Failed to generate binding code for: ${EVISION_GENERATE_LANG}")
endif()
```
3. Then you can edit the source files and recompile `evision.so`.
```shell
mix compile
```
#### Runtime related
- How do I enable debug logging for OpenCV (prints to stderr).
```shell
export OPENCV_EVISION_DEBUG=1
```
Acknowledgements
gen2.py,hdr_parser.pyandc_src/erlcompat.hppwere directly copied from thepythonmodule in the OpenCV repo. Changes applied.Makefile,CMakeLists.txtandc_src/nif_utils.hppwere also copied from thetorchxmodule in the elixir-nx repo. Minor changes applied.