# BP Opencv tutorial

## Build Demo project

### 1. git clone project

### 2. Install plugin

### 3. Generate project

### 4. Build project
Then you can try it.

## How to read example

Our example is porting from [opencv website](https://docs.opencv.org/master/d7/da8/tutorial_table_of_content_imgproc.html)

We use blueprint to implement same function.

## Introduction

For use this plugin, You may want to do image processing or want to draw geometric figures.
First you will need to create an image (CvMat).

There are several methods you can try.

### 1. Read from texture
You can read from unreal texture2D then use function "UpdateTextureToCvMat" to convert texture to opencv mat.

### 2. Create Blank image
Use Cv Zeros use 0 to fill image
Use Cv Ones use 1 to fill image

Then you can show image to mesh or canvas.

### Show CvMat in mesh
Video demo
{%youtube x2hSo44PfvE %}

Blueprint:

### Show CvMat in canvas

Blueprint:

Final we use smoothing example to finish tutorial.

## [Opencv Smoothing Images example](https://docs.opencv.org/master/dc/dd3/tutorial_gausian_median_blur_bilateral_filter.html)

## Initalize from texture

Origin example is read the image from file.
we change it read from texture.

    const char* filename = argc >=2 ? argv[1] : "lena.jpg";
    src = imread( samples::findFile( filename ), IMREAD_COLOR );
    if (src.empty())
    {
        printf(" Error opening image\n");
        printf(" Usage:\n %s [image_name-- default lena.jpg] \n", argv[0]);
        return EXIT_FAILURE;
    }


## Show original image

    if( display_caption( "Original Image" ) != 0 )
    {
        return 0;
    }
    dst = src.clone();
    if( display_dst( DELAY_CAPTION ) != 0 )
    {
        return 0;
    }


## blur

    if( display_caption( "Homogeneous Blur" ) != 0 )
    {
        return 0;
    }
    for ( int i = 1; i < MAX_KERNEL_LENGTH; i = i + 2 )
    {
        blur( src, dst, Size( i, i ), Point(-1,-1) );
        if( display_dst( DELAY_BLUR ) != 0 )
        {
            return 0;
        }
    }


## GaussianBlur

    if( display_caption( "Gaussian Blur" ) != 0 )
    {
        return 0;
    }
    for ( int i = 1; i < MAX_KERNEL_LENGTH; i = i + 2 )
    {
        GaussianBlur( src, dst, Size( i, i ), 0, 0 );
        if( display_dst( DELAY_BLUR ) != 0 )
        {
            return 0;
        }
    }


## medianBlur

    if( display_caption( "Median Blur" ) != 0 )
    {
        return 0;
    }
    for ( int i = 1; i < MAX_KERNEL_LENGTH; i = i + 2 )
    {
        medianBlur ( src, dst, i );
        if( display_dst( DELAY_BLUR ) != 0 )
        {
            return 0;
        }
    }


## bilateralFilter

    if( display_caption( "Bilateral Blur" ) != 0 )
    {
        return 0;
    }
    for ( int i = 1; i < MAX_KERNEL_LENGTH; i = i + 2 )
    {
        bilateralFilter ( src, dst, i, i*2, i/2 );
        if( display_dst( DELAY_BLUR ) != 0 )
        {
            return 0;
        }
    }


you can reference all example from opencv website

https://docs.opencv.org/master/d7/da8/tutorial_table_of_content_imgproc.html

We implement all example of opencv imgproc.