OpenCV

https://docs.opencv.org/4.13.0/
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### Setup Node.js project with jimp

Source: https://docs.opencv.org/4.13.0/dc/de6/tutorial_js_nodejs.html

Creates a new Node.js project directory and installs the jimp dependency for image processing. Run these commands in a terminal before using the image example.

```bash
mkdir project1
cd project1
npm init -y
npm install jimp
```

--------------------------------

### Start local web server and open tests in browser

Source: https://docs.opencv.org/4.13.0/d4/da1/tutorial_js_setup.html

Launch a local web server in the build_js/bin folder and open tests.html in a browser. Requires Node.js to be installed.

```bash
npx http-server build_js/bin
firefox http://localhost:8080/tests.html
```

--------------------------------

### setup() [1/3]

Source: https://docs.opencv.org/4.13.0/da/d6e/classcv_1_1bioinspired_1_1TransientAreasSegmentationModule.html

Tries to open an XML segmentation parameters file to adjust current segmentation instance setup. If the file does not exist, default setup is applied.

```APIDOC
## setup() [1/3]

### Description
Try to open an XML segmentation parameters file to adjust current segmentation instance setup. If the xml file does not exist, then default setup is applied. Warning: Exceptions are thrown if read XML file is not valid.

### Method
setup

### Signature
virtual void cv::bioinspired::TransientAreasSegmentationModule::setup(cv::FileStorage &_fs_, const bool _applyDefaultSetupOnFailure_ = true)

### Parameters
- **fs** (cv::FileStorage&) - Required - The open Filestorage which contains segmentation parameters.
- **applyDefaultSetupOnFailure** (const bool) - Optional - Set to true if an error must be thrown on error. Default is true.

### Returns
None

### Python
cv.bioinspired.TransientAreasSegmentationModule.setup([, segmentationParameterFile[, applyDefaultSetupOnFailure]]) -> None
```

--------------------------------

### setup()

Source: https://docs.opencv.org/4.13.0/dc/d54/classcv_1_1bioinspired_1_1Retina.html

Opens an XML retina parameters file to adjust the current retina instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is not valid.

```APIDOC
## setup()

### Description
Try to open an XML retina parameters file to adjust current retina instance setup. If the xml file does not exist, then default setup is applied. Warning: Exceptions are thrown if read XML file is not valid.

### Method
virtual void cv::bioinspired::Retina::setup(String _retinaParameterFile = "", const bool _applyDefaultSetupOnFailure = true)

### Parameters
- **retinaParameterFile** (String) - Optional - The parameters filename.
- **applyDefaultSetupOnFailure** (bool) - Optional - Set to true if an error must be thrown on error.

### Python Signature
cv.bioinspired.Retina.setup([, retinaParameterFile[, applyDefaultSetupOnFailure]]) -> None

### Notes
You can retrieve the current parameters structure using the method Retina::getParameters and update it before running method Retina::setup.
```

--------------------------------

### Set up Node.js project with canvas and jsdom

Source: https://docs.opencv.org/4.13.0/dc/de6/tutorial_js_nodejs.html

Creates a new Node.js project and installs the canvas and jsdom packages required for the example.

```bash
mkdir project2
cd project2
npm init -y
npm install canvas jsdom
```

--------------------------------

### Build and install OpenCV with make and make install

Source: https://docs.opencv.org/4.13.0/dd/dd5/tutorial_py_setup_in_fedora.html

Build OpenCV with make and install it as root. run make then su, then make install; all files are installed in /usr/local/.

```text
make
su
make install
```

--------------------------------

### Run the example script

Source: https://docs.opencv.org/4.13.0/dc/de6/tutorial_js_nodejs.html

Runs the example script, which should generate the file output.jpg.

```bash
node exampleNodeCanvas.js
```

--------------------------------

### Install OpenCV system-wide

Source: https://docs.opencv.org/4.13.0/d0/db2/tutorial_macos_install.html

Install the compiled binaries to the system.

```bash
sudo make install
```

--------------------------------

### start()

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/core/TickMeter.html

Starts the timer.

```APIDOC
## start()

### Description
Starts the timer.

### Method
Instance Method

### Signature
`public void start()`

### Parameters
None

### Returns
void
```

--------------------------------

### start

Source: https://docs.opencv.org/4.13.0/d0/de8/interfaceCvAbstractCamera.html

Starts the camera capture session.

```APIDOC
## start

### Description
Starts the camera capture session.

### Method
Instance method

### Signature
- (void)start;

### Parameters
None

### Return Value
None

### Example
```objectivec
[camera start];
```
```

--------------------------------

### Quick start install OpenCV on Mac OS X

Source: https://docs.opencv.org/4.13.0/d7/d1e/tutorial_clojure_dev_intro.html

Minimum quick start guide to install OpenCV on Mac OS X, assuming xcode, jdk, and Cmake are already installed. Builds OpenCV with shared libraries disabled.

```bash
cd ~/
mkdir opt
cd opt
git clone https://github.com/opencv/opencv.git
cd opencv
git checkout 2.4
mkdir build
cd build
cmake -DBUILD_SHARED_LIBS=OFF ..
...
...
make -j8
# optional
# make install
```

--------------------------------

### Run the sample executable with command-line options

Source: https://docs.opencv.org/4.13.0/d4/dc0/tutorial_mcc_chart_detection_enhanced_by_neural_network.html

Command-line usage for the sample executable. Options include -t for chart type (0=Standard, 1=DigitalSG, 2=Vinyl), -m for model path, -pb for pbtxt path, -v for video file, --ci for camera ID, --nc for maximum number of charts (default 1), and --use_gpu to enable GPU. Examples show CPU and GPU runs, and limiting to 5 charts.

```bash
<path_of_your_opencv_build_directory>/bin/example_mcc_chart_detection_with_network -t=<type_of_chart> -m=<path_to_neural_network> -pb=<path_to_models_pbtxt> -v=<optional_path_to_video_if_not_provided_webcam_will_be_used.mp4> --ci=<optional_camera_id_needed_only_if_video_not_provided> --nc=<optional_maximum_number_of_charts_in_image> --use_gpu <optional_should_gpu_be_used>
```

```bash
/home/opencv/build/bin/example_mcc_chart_detection_with_network -t=0 -m=/home/model.pb –pb=/home/model.pbtxt -v=mcc24.mp4
```

```bash
/home/opencv/build/bin/example_mcc_chart_detection_with_network -t=0 -m=/home/model.pb –pb=/home/model.pbtxt -v=mcc24.mp4 –use_gpu
```

```bash
/home/opencv/build/bin/example_mcc_chart_detection_with_network -t=0 -m=/home/model.pb –pb=/home/model.pbtxt -v=mcc24.mp4 –use_gpu –nc=5
```

--------------------------------

### pkg-config --cflags opencv - get include paths

Source: https://docs.opencv.org/4.13.0/d7/d16/tutorial_linux_eclipse.html

Terminal command to retrieve the include paths for OpenCV. The example output shows the paths for the installed OpenCV version.

```bash
pkg-config --cflags opencv
```

```bash
-I/usr/local/include/opencv -I/usr/local/include
```

--------------------------------

### Python CamShift example setup

Source: https://docs.opencv.org/4.13.0/d7/d00/tutorial_meanshift.html

Python setup code for the CAMshift sample: imports OpenCV and NumPy, parses a required image/video path argument, and opens the video capture. This is the beginning of the Python version of the camshift tracking example.

```Python
import numpy as np
import cv2 as cv
import argparse
parser = argparse.ArgumentParser(description='This sample demonstrates the camshift algorithm. \
The example file can be downloaded from: \
https://www.bogotobogo.com/python/OpenCV_Python/images/mean_shift_tracking/slow_traffic_small.mp4')
parser.add_argument('image', type=str, help='path to image file')
args = parser.parse_args()
cap = cv.VideoCapture(args.image)
```

--------------------------------

### printSetup()

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/TransientAreasSegmentationModule.html

Parameters setup display method.

```APIDOC
## printSetup()

### Description
Parameters setup display method.

### Method
printSetup

### Signature
`public String printSetup()`

### Returns
- **String** - A string representation of the current setup.

```

--------------------------------

### Using OpenCV in Julia after make install

Source: https://docs.opencv.org/4.13.0/d8/da4/tutorial_julia.html

Start Julia and load the OpenCV package. This works only if you called `make install`.

```julia
$ julia
...
julia> using OpenCV
```

--------------------------------

### setup(String segmentationParameterFile)

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/TransientAreasSegmentationModule.html

Tries to open an XML segmentation parameters file to adjust the current segmentation instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is not valid.

```APIDOC
## setup(String segmentationParameterFile)

### Description
Tries to open an XML segmentation parameters file to adjust the current segmentation instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is not valid.

### Method
setup

### Signature
`public void setup(String segmentationParameterFile)`

### Parameters
- **segmentationParameterFile** (String) - Required - The parameters filename.

```

--------------------------------

### setup

Source: https://docs.opencv.org/4.13.0/d5/d0a/classcv_1_1bioinspired_1_1RetinaFastToneMapping-members.html

Pure virtual method to configure the tone mapping parameters.

```APIDOC
## setup

### Description
Sets up the tone mapping parameters for the RetinaFastToneMapping instance.

### Method
setup

### Signature
`void setup(float photoreceptorsNeighborhoodRadius = 3.f, float ganglioncellsNeighborhoodRadius = 1.f, float meanLuminanceModulatorK = 1.f) = 0`

### Parameters
- **photoreceptorsNeighborhoodRadius** (float) - Optional - Radius of the photoreceptors neighborhood. Default is 3.0.
- **ganglioncellsNeighborhoodRadius** (float) - Optional - Radius of the ganglion cells neighborhood. Default is 1.0.
- **meanLuminanceModulatorK** (float) - Optional - Modulator for mean luminance. Default is 1.0.

### Return Value
None (void).
```

--------------------------------

### Install git for cloning repository

Source: https://docs.opencv.org/4.13.0/d7/d9f/tutorial_linux_install.html

Installs git, used to clone the OpenCV repository and get the full change history.

```bash
sudo apt install -y git
```

--------------------------------

### setup(String segmentationParameterFile, boolean applyDefaultSetupOnFailure)

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/TransientAreasSegmentationModule.html

Tries to open an XML segmentation parameters file to adjust the current segmentation instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is not valid.

```APIDOC
## setup(String segmentationParameterFile, boolean applyDefaultSetupOnFailure)

### Description
Tries to open an XML segmentation parameters file to adjust the current segmentation instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is not valid.

### Method
setup

### Signature
`public void setup(String segmentationParameterFile, boolean applyDefaultSetupOnFailure)`

### Parameters
- **segmentationParameterFile** (String) - Required - The parameters filename.
- **applyDefaultSetupOnFailure** (boolean) - Required - Set to true if an error must be thrown on error.

```

--------------------------------

### Get vertices from a RotatedRect using cv.RotatedRect.points

Source: https://docs.opencv.org/4.13.0/d5/df1/tutorial_js_some_data_structures.html

Use cv.RotatedRect.points(rotatedRect) to get an array of four vertices. The example assigns each vertex to point1 through point4.

```javascript
let vertices = cv.RotatedRect.points(rotatedRect);
let point1 = vertices[0];
let point2 = vertices[1];
let point3 = vertices[2];
let point4 = vertices[3];
```

--------------------------------

### ldd output showing all libraries installed

Source: https://docs.opencv.org/4.13.0/d3/dd9/tutorial_crosscompile_with_multiarch.html

Example output of ldd when all required libraries are installed. The line 'libharfbuzz.so.0 => /lib/aarch64-linux-gnu/libharfbuzz.so.0' indicates the library is found.

```text
linux-vdso.so.1 (0xABCDEFG01234567)
libopencv_imgproc.so.408 => /usr/local/lib/libopencv_imgproc.so.408 (0xABCDEF001234567)
libfreetype.so.6 => /lib/aarch64-linux-gnu/libfreetype.so.6 (0xABCDEF001234567)
libharfbuzz.so.0 => /lib/aarch64-linux-gnu/libharfbuzz.so.0 (0xABCDEF001234567)
libopencv_core.so.408 => /usr/local/lib/libopencv_core.so.408 (0xABCDEF001234567)
:
```

--------------------------------

### setup (String)

Source: https://docs.opencv.org/4.13.0/dc/d54/classcv_1_1bioinspired_1_1Retina.html

Tries to open an XML retina parameters file to adjust current retina instance setup.

```APIDOC
## setup (String)

### Description
Tries to open an XML retina parameters file to adjust current retina instance setup.

### Method
virtual void setup(String retinaParameterFile="", const bool applyDefaultSetupOnFailure=true)=0

### Parameters
- **retinaParameterFile** (String) - Optional - The path to the XML parameters file. Default is empty string.
- **applyDefaultSetupOnFailure** (bool) - Optional - If true, applies default setup on failure. Default is true.

```

--------------------------------

### Colorization DNN Example: Includes and Namespaces

Source: https://docs.opencv.org/4.13.0/d6/d39/samples_2dnn_2colorization_8cpp-example.html

Includes the necessary OpenCV headers for DNN, image processing, and GUI, and declares the cv and cv::dnn namespaces. This is the setup required for the colorization example.

```cpp
// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html
#include <opencv2/dnn.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>
using namespace cv;
using namespace cv::dnn;
using namespace std;
```

--------------------------------

### setup(String, bool)

Source: https://docs.opencv.org/4.13.0/da/d6e/classcv_1_1bioinspired_1_1TransientAreasSegmentationModule.html

Attempts to open an XML segmentation parameters file to adjust the current segmentation instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the read XML file is not valid.

```APIDOC
## setup(String, bool)

### Description
Attempts to open an XML segmentation parameters file to adjust the current segmentation instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the read XML file is not valid.

### Method
setup

### Signature
virtual void cv::bioinspired::TransientAreasSegmentationModule::setup(String _segmentationParameterFile_ = "", const bool _applyDefaultSetupOnFailure_ = true) pure virtual

### Python
cv.bioinspired.TransientAreasSegmentationModule.setup([, segmentationParameterFile[, applyDefaultSetupOnFailure]]) -> None

### Parameters
- **segmentationParameterFile** (String) - Optional - The parameters filename.
- **applyDefaultSetupOnFailure** (bool) - Optional - Set to true if an error must be thrown on error.

### Returns
None

```

--------------------------------

### Install optional image format dependencies for OpenCV

Source: https://docs.opencv.org/4.13.0/d2/de6/tutorial_py_setup_in_ubuntu.html

Install development files for system libraries of image formats like PNG, JPEG, TIFF, and WebP to get the latest versions. These are optional; you can skip them if not needed.

```bash
sudo apt-get install libpng-dev
```

```bash
sudo apt-get install libjpeg-dev
```

```bash
sudo apt-get install libopenexr-dev
```

```bash
sudo apt-get install libtiff-dev
```

```bash
sudo apt-get install libwebp-dev
```

--------------------------------

### setup(String, boolean)

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/Retina.html

Attempts to open an XML retina parameters file to adjust the current retina instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is invalid.

```APIDOC
## setup(String, boolean)

### Description
Attempts to open an XML retina parameters file to adjust the current retina instance setup. If the file does not exist, default setup is applied. Exceptions are thrown if the XML file is invalid.

### Method
`public void setup(String retinaParameterFile, boolean applyDefaultSetupOnFailure)`

### Parameters
- `retinaParameterFile` (String) - the parameters filename
- `applyDefaultSetupOnFailure` (boolean) - set to true if an error must be thrown on error
```

--------------------------------

### Check dependencies with ldd on target

Source: https://docs.opencv.org/4.13.0/d3/dd9/tutorial_crosscompile_with_multiarch.html

Uses ldd to check if all required libraries are installed. If any 'not found' appears, install the missing libraries. The example shows a missing libharfbuzz.so.0 and a good case where all libraries are found.

```bash
ldd /usr/local/lib/libopencv_freetype.so
```

--------------------------------

### printSetup

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/TransientAreasSegmentationModule.html

Returns a formatted string containing the current parameters setup information.

```APIDOC
## printSetup

### Description
Returns a formatted string containing the current parameters setup information.

### Method
printSetup

### Returns
- **String** - A string containing formatted parameters information.

```

--------------------------------

### Set ESDK_ROOT environment variable

Source: https://docs.opencv.org/4.13.0/d5/d06/tutorial_building_fastcv.html

Sets the ESDK_ROOT variable to the eSDK install location. Required before sourcing the environment setup script.

```bash
export ESDK_ROOT=<eSDK install location>
```

--------------------------------

### setup (FileStorage)

Source: https://docs.opencv.org/4.13.0/dc/d54/classcv_1_1bioinspired_1_1Retina.html

Sets up the retina from a FileStorage.

```APIDOC
## setup (FileStorage)

### Description
Sets up the retina from a FileStorage.

### Method
virtual void setup(cv::FileStorage &fs, const bool applyDefaultSetupOnFailure=true)=0

### Parameters
- **fs** (cv::FileStorage&) - Required - The file storage containing the parameters.
- **applyDefaultSetupOnFailure** (bool) - Optional - If true, applies default setup on failure. Default is true.

```

--------------------------------

### getPathToApplication()

Source: https://docs.opencv.org/4.13.0/d0/d2e/classcv_1_1CommandLineParser.html

Returns the path to the executable from the command line (argv[0]). For example, if the application was started with `./bin/my-executable`, this method returns `./bin`.

```APIDOC
## getPathToApplication()

### Description
Returns the path to the executable from the command line (argv[0]). For example, if the application was started with `./bin/my-executable`, this method returns `./bin`.

### Method
`String cv::CommandLineParser::getPathToApplication() const`
```

--------------------------------

### setup()

Source: https://docs.opencv.org/4.13.0/dd/d73/classcv_1_1bioinspired_1_1RetinaFastToneMapping.html

Updates tone mapping behaviors by adjusting the local luminance computation area.

```APIDOC
## setup()

### Description
Updates tone mapping behaviors by adjusting the local luminance computation area.

### Method
setup

### Signature
virtual void cv::bioinspired::RetinaFastToneMapping::setup(const float _photoreceptorsNeighborhoodRadius_ = 3.f, const float _ganglioncellsNeighborhoodRadius_ = 1.f, const float _meanLuminanceModulatorK_ = 1.f)

### Parameters
- **_photoreceptorsNeighborhoodRadius** (float) - Optional - The first stage local adaptation area. Default is 3.f.
- **_ganglioncellsNeighborhoodRadius** (float) - Optional - The second stage local adaptation area. Default is 1.f.
- **_meanLuminanceModulatorK** (float) - Optional - The factor applied to modulate the meanLuminance information. Default is 1.f.

### Python API
- cv.bioinspired.RetinaFastToneMapping.setup([, photoreceptorsNeighborhoodRadius[, ganglioncellsNeighborhoodRadius[, meanLuminanceModulatorK]]]) -> None

### Returns
- None
```

--------------------------------

### Initialize Camera and Projector Window

Source: https://docs.opencv.org/4.13.0/d0/de8/tutorial_capture_sinusoidal_pattern.html

Opens the camera and sets up a full-screen window for pattern projection.

```cpp
VideoCapture cap(CAP_PVAPI);
if( !cap.isOpened() )
{
cout << "Camera could not be opened" << endl;
return -1;
}
cap.set(CAP_PROP_PVAPI_PIXELFORMAT, CAP_PVAPI_PIXELFORMAT_MONO8);
namedWindow("pattern", WINDOW_NORMAL);
setWindowProperty("pattern", WND_PROP_FULLSCREEN, WINDOW_FULLSCREEN);
imshow("pattern", patterns[0]);
cout << "Press any key when ready" << endl;
waitKey(0);
```

--------------------------------

### Setup Emscripten upstream backend environment

Source: https://docs.opencv.org/4.13.0/d4/da1/tutorial_js_setup.html

Commands to update, install, activate latest-upstream, and source emsdk_env.sh. Required for wasm simd optimization.

```bash
./emsdk update
./emsdk install latest-upstream
./emsdk activate latest-upstream
source ./emsdk_env.sh
```

--------------------------------

### Python morphology lines detection script header

Source: https://docs.opencv.org/4.13.0/dd/dd7/tutorial_morph_lines_detection.html

Python version of the morphology lines detection example. It imports numpy and OpenCV, defines a helper to display and destroy windows, and starts the main function. This is the beginning of the Python script that mirrors the Java example.

```Python
"""
@file morph_lines_detection.py
@brief Use morphology transformations for extracting horizontal and vertical lines sample code
"""
import numpy as np
import sys
import cv2 as cv
def show_wait_destroy(winname, img):
cv.imshow(winname, img)
cv.moveWindow(winname, 500, 0)
cv.waitKey(0)
cv.destroyWindow(winname)
def main(argv):
```

--------------------------------

### printSetup()

Source: https://docs.opencv.org/4.13.0/da/d6e/classcv_1_1bioinspired_1_1TransientAreasSegmentationModule.html

Returns a string containing formatted parameters information for the segmentation module setup.

```APIDOC
## printSetup()

### Description
Returns a string which contains formatted parameters information.

### Method
printSetup

### Signature
virtual String cv::bioinspired::TransientAreasSegmentationModule::printSetup()

### Parameters
None

### Returns
- **retval** (String) - A string containing formatted parameters information.

### Python
cv.bioinspired.TransientAreasSegmentationModule.printSetup() -> retval
```

--------------------------------

### RotatedRect usage example

Source: https://docs.opencv.org/4.13.0/db/dd6/classcv_1_1RotatedRect.html

Demonstrates how to use RotatedRect: constructs a rotated rectangle, retrieves its four vertices, draws them, gets the bounding rectangle, and displays the result.

```cpp
Mat test_image(200, 200, CV_8UC3, Scalar(0));
RotatedRect rRect = RotatedRect(Point2f(100,100), Size2f(100,50), 30);
Point2f vertices[4];
rRect.points(vertices);
for (int i = 0; i < 4; i++)
{
line(test_image, vertices[i], vertices[(i+1)%4], Scalar(0,255,0), 2);
putText(test_image, vertex_names[i], vertices[i], FONT_HERSHEY_SIMPLEX, 1, Scalar(255,255,255));
}
Rect brect = rRect.boundingRect();
rectangle(test_image, brect, Scalar(255,0,0), 2);
imshow("rectangles", test_image);
waitKey(0);
```

--------------------------------

### setup(String retinaParameterFile)

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/Retina.html

Sets up the retina model from a parameter file.

```APIDOC
## setup(String retinaParameterFile)

### Description
Sets up the retina model from a parameter file.

### Method
setup

### Parameters
- **retinaParameterFile** (String) - Required - Path to the parameter file.

### Returns
void
```

--------------------------------

### ldd output showing missing library

Source: https://docs.opencv.org/4.13.0/d3/dd9/tutorial_crosscompile_with_multiarch.html

Example output of ldd when a required library (libharfbuzz.so.0) is not installed. The line 'libharfbuzz.so.0 => not found' indicates the missing dependency.

```text
linux-vdso.so.1 (0xABCDEFG01234567)
libopencv_imgproc.so.408 => /usr/local/lib/libopencv_imgproc.so.408 (0xABCDEF001234567)
libfreetype.so.6 => /lib/aarch64-linux-gnu/libfreetype.so.6 (0xABCDEF001234567)
libharfbuzz.so.0 => not found
libopencv_core.so.408 => /usr/local/lib/libopencv_core.so.408 (0xABCDEF001234567)
:
```

--------------------------------

### setup(String retinaParameterFile, boolean applyDefaultSetupOnFailure)

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/bioinspired/Retina.html

Loads retina parameters from an XML file, with an option to apply default setup on failure.

```APIDOC
## setup(String retinaParameterFile, boolean applyDefaultSetupOnFailure)

### Description
Loads retina parameters from an XML file, with an option to apply default setup on failure.

### Method
void setup(String retinaParameterFile, boolean applyDefaultSetupOnFailure)

### Parameters
- **retinaParameterFile** (String) - Path to the XML parameter file.
- **applyDefaultSetupOnFailure** (boolean) - Whether to apply default setup if loading fails.

### Returns
void
```

--------------------------------

### setup (String)

Source: https://docs.opencv.org/4.13.0/da/d6e/classcv_1_1bioinspired_1_1TransientAreasSegmentationModule.html

Sets up the segmentation instance from an XML parameters file specified by a string path.

```APIDOC
## setup (String)

### Description
Try to open an XML segmentation parameters file to adjust current segmentation instance setup.

### Method
virtual void setup(String segmentationParameterFile = "", const bool applyDefaultSetupOnFailure = true) = 0

### Parameters
- **segmentationParameterFile** (String) - Optional - The path to the XML parameters file (default "").
- **applyDefaultSetupOnFailure** (const bool) - Optional - Whether to apply default setup on failure (default true).

### Returns
void
```

--------------------------------

### Access pixel values with ucharPtr

Source: https://docs.opencv.org/4.13.0/de/d06/tutorial_js_basic_ops.html

Accesses pixel values using the ptr manipulation with ucharPtr for CV_8U matrices. mat.ucharPtr(k) gets the k-th row, mat.ucharPtr(i, j) gets the i-th row and j-th column. The example reads R, G, B, A at row 3, col 4.

```javascript
let row = 3, col = 4;
let src = cv.imread("canvasInput");
let pixel = src.ucharPtr(row, col);
let R = pixel[0];
let G = pixel[1];
let B = pixel[2];
let A = pixel[3];

```

--------------------------------

### Using OpenCV in Julia without make install (set JULIA_LOAD_PATH)

Source: https://docs.opencv.org/4.13.0/d8/da4/tutorial_julia.html

Set the environment variable `JULIA_LOAD_PATH` to the directory containing the OpenCV package, then start Julia and load OpenCV.

```julia
$ export JULIA_LOAD_PATH=$PWD/OpenCV
$ julia
...
julia> using OpenCV
```

--------------------------------

### Install OpenCV Julia bindings with pkg add OpenCV

Source: https://docs.opencv.org/4.13.0/d8/da4/tutorial_julia.html

Start the Julia REPL, press ] to enter package mode, then run add OpenCV. Verified on Julia v1.6.1.

```julia
$ julia
...
julia> ]
pkg> add OpenCV
```

--------------------------------

### Run cpp-tutorial-pnp_detection with custom options

Source: https://docs.opencv.org/4.13.0/dc/d2c/tutorial_real_time_pose.html

Command-line invocation of the tutorial program with configurable options. The ratio test threshold, number of keypoints to detect, and whether to use the robust matcher can be changed via --ratio, --keypoints, and --fast.

```bash
./cpp-tutorial-pnp_detection --ratio=0.8 --keypoints=1000 --fast=false
```

--------------------------------

### setup(String) - Retina

Source: https://docs.opencv.org/4.13.0/javadoc/index-all.html

Configures the Retina instance by loading an XML parameters file from the given path. If the file does not exist, default setup is applied.

```APIDOC
## setup(String) - Retina

### Description
Try to open an XML retina parameters file to adjust current retina instance setup. If the XML file does not exist, default setup is applied. Exceptions are thrown if the read XML file is not valid.

### Method
setup

### Class
org.opencv.bioinspired.Retina

### Parameters
- **filePath** (String) - Required - Path to the XML parameters file.

### Return
void

### Usage
Call with a file path string to load retina parameters from XML.
```

--------------------------------

### Get channel count and create result image (Java)

Source: https://docs.opencv.org/4.13.0/d7/d37/tutorial_mat_mask_operations.html

Java equivalent of the basic method setup: obtains the channel count and creates the output image with the same size and type.

```Java
int nChannels = myImage.channels();
Result.create(myImage.size(), myImage.type());
```

--------------------------------

### Get classification result with minMaxLoc

Source: https://docs.opencv.org/4.13.0/dd/d55/pytorch_cls_c_tutorial_dnn_conversion.html

Finds the class with the highest confidence using minMaxLoc on the reshaped probability matrix. The resulting classId for the example is 335, corresponding to the fox squirrel.

```cpp
Point classIdPoint;
double confidence;
minMaxLoc(prob.reshape(1, 1), 0, &confidence, 0, &classIdPoint);
int classId = classIdPoint.x;
```

--------------------------------

### Set up Intel oneAPI environment

Source: https://docs.opencv.org/4.13.0/d9/d08/tutorial_oneapi_install.html

Loads the Intel oneAPI environment variables for the default installation.

```bash
source /opt/intel/oneapi/setvars.sh
```

--------------------------------

### printSetup

Source: https://docs.opencv.org/4.13.0/da/d6e/classcv_1_1bioinspired_1_1TransientAreasSegmentationModule.html

Displays the current parameters setup.

```APIDOC
## printSetup

### Description
Parameters setup display method.

### Method
virtual String printSetup() = 0

### Parameters
None

### Returns
String - a string representation of the setup
```

--------------------------------

### ViewController interface with IBOutlets and IBAction

Source: https://docs.opencv.org/4.13.0/db/dc8/tutorial_video_processing.html

Declares the ViewController interface with an UIImageView and UIButton outlet, and an action to start the camera. This is the initial setup after creating a Single View Application and connecting the storyboard elements.

```objectivec
@interface ViewController : UIViewController
{
IBOutlet UIImageView* imageView;
IBOutlet UIButton* button;
}
- (IBAction)actionStart:(id)sender;
@end
```

--------------------------------

### Build and run OpenCV sample: make and execute

Source: https://docs.opencv.org/4.13.0/d3/dd9/tutorial_crosscompile_with_multiarch.html

Commands to build the sample using make and run the resulting a.out executable on the target.

```bash
make a.out
./a.out
```

--------------------------------

### Python: Animated WebP example (incomplete)

Source: https://docs.opencv.org/4.13.0/d5/dfb/tutorial_animations.html

This Python code snippet is incomplete in the source, showing only the imports and the start of a main function. It is intended to be part of the animations tutorial but the rest of the code is not provided.

```Python
import cv2 as cv
import numpy as np
def main(filename):
if filename == "animated_image.webp":
```

--------------------------------

### setup (RetinaParameters)

Source: https://docs.opencv.org/4.13.0/dc/d54/classcv_1_1bioinspired_1_1Retina.html

Sets up the retina with new parameters.

```APIDOC
## setup (RetinaParameters)

### Description
Sets up the retina with new parameters.

### Method
virtual void setup(RetinaParameters newParameters)=0

### Parameters
- **newParameters** (RetinaParameters) - Required - The new parameters to set.

```

--------------------------------

### pkg-config --libs opencv - get library paths and names

Source: https://docs.opencv.org/4.13.0/d7/d16/tutorial_linux_eclipse.html

Terminal command to retrieve the library search paths and library names for OpenCV. The example output lists the libraries needed for linking.

```bash
pkg-config --libs opencv
```

```bash
-L/usr/local/lib -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_videoio -lopencv_imgcodecs -lopencv_flann
```

--------------------------------

### Python: Main script - Argument parsing and image loading

Source: https://docs.opencv.org/4.13.0/da/d0c/tutorial_bounding_rects_circles.html

Parses command-line arguments to get the input image path (default 'stuff.jpg'), loads the image, and exits if it cannot be opened. This is the entry point for the Python example.

```python
parser = argparse.ArgumentParser(description='Code for Creating Bounding boxes and circles for contours tutorial.')
parser.add_argument('--input', help='Path to input image.', default='stuff.jpg')
args = parser.parse_args()
src = cv.imread(cv.samples.findFile(args.input))
if src is None:
    print('Could not open or find the image:', args.input)
    exit(0)
```

--------------------------------

### Example CMake configuration for ARM build

Source: https://docs.opencv.org/4.13.0/d0/d76/tutorial_arm_crosscompile_with_cmake.html

Example commands to create a build directory and run CMake with the toolchain file.

```bash
cd ~/opencv/platforms/linux
mkdir -p build_hardfp
cd build_hardfp
cmake -DCMAKE_TOOLCHAIN_FILE=../arm-gnueabi.toolchain.cmake ../../..
```

--------------------------------

### findNonZero with cv::Mat output

Source: https://docs.opencv.org/4.13.0/javadoc/org/opencv/core/Core.html

Example of using cv::findNonZero to get non-zero pixel locations into a cv::Mat. The function does not work with multi-channel arrays; use Mat::reshape or extract channels for multi-channel input.

```cpp
      cv::Mat binaryImage; // input, binary image
      cv::Mat locations;   // output, locations of non-zero pixels
      cv::findNonZero(binaryImage, locations); 
      // access pixel coordinates
      Point pnt = locations.at<Point>(i);  
```

--------------------------------

### setup (SegmentationParameters)

Source: https://docs.opencv.org/4.13.0/da/d6e/classcv_1_1bioinspired_1_1TransientAreasSegmentationModule.html

Sets up the segmentation instance with new parameters.

```APIDOC
## setup (SegmentationParameters)

### Description
Try to open an XML segmentation parameters file to adjust current segmentation instance setup. (Overload that takes parameters directly.)

### Method
virtual void setup(SegmentationParameters newParameters) = 0

### Parameters
- **newParameters** (SegmentationParameters) - Required - The new parameters to set.

### Returns
void
```

--------------------------------

### getTemplates(String class_id, int template_id)

Source: https://docs.opencv.org/4.13.0/d7/d07/classcv_1_1linemod_1_1Detector.html

Gets the template pyramid identified by template_id. For example, with 2 modalities (Gradient, Normal) and two pyramid levels (L0, L1), the order is (GradientL0, NormalL0, GradientL1, NormalL1).

```APIDOC
## getTemplates(String class_id, int template_id)

### Description
Gets the template pyramid identified by template_id. For example, with 2 modalities (Gradient, Normal) and two pyramid levels (L0, L1), the order is (GradientL0, NormalL0, GradientL1, NormalL1).

### Method
getTemplates

### Signature
const std::vector<Template>& cv::linemod::Detector::getTemplates(const String& class_id, int template_id) const

### Parameters
- **class_id** (String) - Required - The class ID of the templates.
- **template_id** (int) - Required - The template ID.

### Returns
- **retval** (const std::vector<Template>&) - The template pyramid.
```

--------------------------------

### Set Up Fullscreen Projection Window

Source: https://docs.opencv.org/4.13.0/db/d56/tutorial_capture_graycode_pattern.html

Creates a window for the projector, resizes it to the pattern dimensions, moves it to the projector's monitor, and sets it to fullscreen.

```cpp
// Setting pattern window on second monitor (the projector's one)
namedWindow( "Pattern Window", WINDOW_NORMAL );
resizeWindow( "Pattern Window", params.width, params.height );
moveWindow( "Pattern Window", params.width + 316, -20 );
setWindowProperty( "Pattern Window", WND_PROP_FULLSCREEN, WINDOW_FULLSCREEN );
```

--------------------------------

### Denoise a video frame sequence with cv.fastNlMeansDenoisingMulti()

Source: https://docs.opencv.org/4.13.0/d5/d69/tutorial_py_non_local_means.html

Captures a video, extracts frames, and applies Non-local Means denoising to a specific frame using nearby frames. The example is incomplete in the source, showing only the video capture setup.

```python
import numpy as np
import cv2 as cv
from matplotlib import pyplot as plt
cap = cv.VideoCapture('vtest.avi')
```

--------------------------------

### Command line for calibrate_camera_charuco.cpp (C++)

Source: https://docs.opencv.org/4.13.0/da/d13/tutorial_aruco_calibration.html

Command-line example for the full calibration sample in calibrate_camera_charuco.cpp, showing expected parameters via cv::CommandLineParser.

```text
"camera_calib.txt" -w=5 -h=7 -sl=0.04 -ml=0.02 -d=10
-v=path/img_%02d.jpg
```
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