Set Up Your C++ Compiler

To build the OpenCV libraries, identify a compatible C++ compiler for your operating system, as described inPortable C Code Generation for Functions That Use OpenCV Library. Configure the identified compiler by using themex -setup c++command. For more information, seeChoose a C++ Compiler.

Model Description

This example uses the Simulink modelToGrayScale.slx.

In this model, thesubsystem_slwrap_toGrayScalesubsystem resides in theRGBtoGRAY_Liblibrary. You create thesubsystem_slwrap_toGrayScalesubsystem by using theOpenCV Importer. The subsystem accepts an RGB image from the Image From File block and converts it to a grayscale output image. The output is then displayed on a Video Viewer block.

Copy Example Folder to a Writable Location

To access the path to the example folder, at the MATLAB® command line, enter:

OpenCVSimulinkExamples;

Each subfolder contains all the supporting files required to run the example.

Before proceeding with these steps, ensure that you copy the example folder to a writable folder location and change your current working folder to...example\ImageRGBtoGray. All your output files are saved to this folder.

Step 1: Import OpenCV Function to Create a Simulink Library

1. To start theOpenCV Importerapp, clickAppson the MATLAB Toolstrip. In the Welcome page, specify theProject nameasRGBtoGRAY. Make sure that the project name does not contain any spaces. ClickNext.

2. In Specify OpenCV Library, specify these file locations, and then clickNext.

3. Analyze your library to find the functions and types for import. Once the analysis is complete, clickNext. Select thetoGrayScalefunction and clickNext.

4. From What to import, select theI/O TypeforimgasInputOutput, and then clickNext.

5. In Create Simulink Library, configure the default values of OpenCV types. By default,Create a single C-caller block for the OpenCV function选择创建一个C调用块一起吗the subsystem in the generated Simulink library.

6. SelectConfigure library to use Simulink.ImageType signalsto configure the generated library subsystem to useSimulink.ImageTypesignals.

7. SetDefault Color Format of Simlink.ImageType signaltoRGB, which is the default color format of the image.

8. SetDefault Array layout of Simulink.ImageType signaltoColumn-major, which is the default array layout of the image.

9. To create a Simulink library, clickNext.

A Simulink libraryRGBtoGRAY_Libis created from your OpenCV code into the project root folder. The library contains a subsystem and a C Caller block. You can use any of these blocks for model simulation. In this example, the subsystemsubsystem_slwrap_toGrayScaleis used.

Step 2: Use Generated Subsystem in Simulink Model

To use the generated subsystemsubsystem_slwrap_toGrayScalewith the Simulink modelToGrayScale.slx:

1. In your MATLAB current folder, right-click the modelToGrayScale.slxand clickOpenfrom the context menu. Drag the generated subsystem from the library to the model. Insert the subsystem between From Multimedia File block and Video Viewer block.

2. Double-click the subsystem and configure these parameter values:

3. ClickApply, and then clickOK.

Step 3: Simulate the RGB to Gray Convertor

On the Simulink Toolstrip, in theSimulationtab, click onRunto simulate the model. After the simulation is complete, the Video Viewer block displays the grayscale image of the input imagepeppers.png.