Merge branch 4.x

2026-07-29 15:23:05 +04:00 · 2024-01-23 17:06:52 +03:00
parent d6424233f0 69772b0260
commit decf6538a2
148 changed files with 3263 additions and 1564 deletions
@@ -9,6 +9,9 @@ How to use the OpenCV parallel_for_ to parallelize your code {#tutorial_how_to_u
 | -: | :- |
 | Compatibility | OpenCV >= 3.0 |

+
+@note See also C++ lambda usage with parallel for in [tuturial](@ref tutorial_how_to_use_OpenCV_parallel_for_new).
+
 Goal
 ----

@@ -20,7 +23,7 @@ If you want more information about multithreading, you will have to refer to a r
 to remain simple.

 Precondition
----
+------------

 The first precondition is to have OpenCV built with a parallel framework.
 In OpenCV 3.2, the following parallel frameworks are available in that order:
@@ -50,7 +53,7 @@ We will use the example of drawing a Mandelbrot set to show how from a regular s
 the code to parallelize the computation.

 Theory
-----------
+------

 The Mandelbrot set definition has been named in tribute to the mathematician Benoit Mandelbrot by the mathematician
 Adrien Douady. It has been famous outside of the mathematics field as the image representation is an example of a
@@ -69,7 +72,7 @@ Here, we will just introduce the formula to draw the Mandelbrot set (from the me
 > \f[\limsup_{n\to\infty}|z_{n+1}|\leqslant2\f]

 Pseudocode
-----------
+----------

 A simple algorithm to generate a representation of the Mandelbrot set is called the
 ["escape time algorithm"](https://en.wikipedia.org/wiki/Mandelbrot_set#Escape_time_algorithm).
@@ -110,10 +113,10 @@ On this figure, we recall that the real part of a complex number is on the x-axi
 You can see that the whole shape can be repeatedly visible if we zoom at particular locations.

 Implementation
-----------
+--------------

 Escape time algorithm implementation
--------------------------
+------------------------------------

@snippet how_to_use_OpenCV_parallel_for_.cpp mandelbrot-escape-time-algorithm

@@ -121,7 +124,7 @@ Here, we used the [`std::complex`](http://en.cppreference.com/w/cpp/numeric/comp
 complex number. This function performs the test to check if the pixel is in set or not and returns the "escaped" iteration.

 Sequential Mandelbrot implementation
--------------------------
+------------------------------------

@snippet how_to_use_OpenCV_parallel_for_.cpp mandelbrot-sequential

@@ -149,7 +152,7 @@ The green curve corresponds to a simple linear scale transformation, the blue on
 and you can observe how the lowest values will be boosted when looking at the slope at these positions.

 Parallel Mandelbrot implementation
--------------------------
+----------------------------------

 When looking at the sequential implementation, we can notice that each pixel is computed independently. To optimize the
 computation, we can perform multiple pixel calculations in parallel, by exploiting the multi-core architecture of modern
@@ -181,7 +184,7 @@ C++ 11 standard allows to simplify the parallel implementation by get rid of the
@snippet how_to_use_OpenCV_parallel_for_.cpp mandelbrot-parallel-call-cxx11

 Results
-----------
+-------

 You can find the full tutorial code [here](https://github.com/opencv/opencv/blob/5.x/samples/cpp/tutorial_code/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_.cpp).
 The performance of the parallel implementation depends of the type of CPU you have. For instance, on 4 cores / 8 threads
@@ -18,7 +18,7 @@ This tutorial assumes you have the following installed and configured:
 -   Android Studio
 -   JDK
 -   Android SDK and NDK
-   OpenCV for Android SDK from official [release page on Github](https://github.com/opencv/opencv/releases)
+-   Optional: OpenCV for Android SDK from official [release page on Github](https://github.com/opencv/opencv/releases)
    or [SourceForge](https://sourceforge.net/projects/opencvlibrary/). Advanced: as alternative the SDK may be
    built from source code by [instruction on wiki](https://github.com/opencv/opencv/wiki/Custom-OpenCV-Android-SDK-and-AAR-package-build).

@@ -26,8 +26,9 @@ If you need help with anything of the above, you may refer to our @ref tutorial_

 If you encounter any error after thoroughly following these steps, feel free to contact us via OpenCV [forum](https://forum.opencv.org). We'll do our best to help you out.

-Hello OpenCV sample
-------------------
+
+Hello OpenCV sample with SDK
+----------------------------

 In this section we're gonna create a simple app that does nothing but OpenCV loading. In next section we'll extend it to support camera.

@@ -75,11 +76,10 @@ In addition to this instruction you can use some video guide, for example [this
    @endcode
    The fix was found [here](https://stackoverflow.com/questions/73225714/import-opencv-sdk-to-android-studio-chipmunk)

-6. OpenCV project uses `aidl` and `buildConfig` features. Please enable them in
+6. OpenCV project uses `buildConfig` feature. Please enable it in
   `MyApplication/OpenCV/build.gradle` file to `android` block:
    @code{.gradle}
    buildFeatures{
-        aidl true
        buildConfig true
    }

@@ -115,6 +115,43 @@ In addition to this instruction you can use some video guide, for example [this

    ![](images/run_app.png)

+Hello OpenCV sample with Maven Central
+--------------------------------------
+
+Since OpenCV 4.9.0 OpenCV for Android package is available with Maven Central and may be installed
+automatically as Gradle dependency. In this section we're gonna create a simple app that does nothing
+but OpenCV loading with Maven Central.
+
+1. Open Android Studio and create empty project by choosing ***Empty Views Activity***
+
+    ![](images/create_empty_project.png)
+
+2. Setup the project:
+    - Choose ***Java*** language
+    - Choose ***Groovy DSL*** build configuration language
+    - Choose ***Minumum SDK*** with the version number not less than OpenCV supports. For 4.9.0 minimal SDK version is 21.
+
+    ![](images/setup_project.png)
+
+3. Edit `build.gradle` and add OpenCV library to Dependencies list like this:
+    @code{.gradle}
+    dependencies {
+        implementation 'org.opencv:opencv:4.9.0'
+    }
+    @endcode
+   `4.9.0` may be replaced by any version available as [official release](https://central.sonatype.com/artifact/org.opencv/opencv).
+
+4. Before using any OpenCV function you have to load the library first. If you application includes other
+   OpenCV-dependent native libraries you should load them ***after*** OpenCV initialization. Add the folowing
+   code to load the library at app start:
+    @snippet samples/android/tutorial-1-camerapreview/src/org/opencv/samples/tutorial1/Tutorial1Activity.java ocv_loader_init
+    Like this:
+    ![](images/sample_code.png)
+
+5. Choose a device to check the sample on and run the code by pressing `run` button
+
+    ![](images/run_app.png)
+
 Camera view sample
 ------------------

@@ -378,6 +378,9 @@ our OpenCV library that we use in our projects. Start up a command window and en

    setx OpenCV_DIR D:\OpenCV\build\x64\vc16     (suggested for Visual Studio 2019 - 64 bit Windows)
    setx OpenCV_DIR D:\OpenCV\build\x86\vc16     (suggested for Visual Studio 2019 - 32 bit Windows)
+
+    setx OpenCV_DIR D:\OpenCV\build\x64\vc17     (suggested for Visual Studio 2022 - 64 bit Windows)
+    setx OpenCV_DIR D:\OpenCV\build\x86\vc17     (suggested for Visual Studio 2022 - 32 bit Windows)
@endcode
 Here the directory is where you have your OpenCV binaries (*extracted* or *built*). You can have
 different platform (e.g. x64 instead of x86) or compiler type, so substitute appropriate value.