diff --git a/modules/v4d/include/opencv2/v4d/nvg.hpp b/modules/v4d/include/opencv2/v4d/nvg.hpp
index 547515091..af65c65f3 100644
--- a/modules/v4d/include/opencv2/v4d/nvg.hpp
+++ b/modules/v4d/include/opencv2/v4d/nvg.hpp
@@ -6,8 +6,6 @@
 #ifndef SRC_OPENCV_V4D_NVG_HPP_
 #define SRC_OPENCV_V4D_NVG_HPP_
 
-//#include "v4d.hpp"
-
 #include <stdio.h>
 #include <opencv2/core.hpp>
 #include "nanovg.h"
@@ -17,7 +15,7 @@ struct NVGcontext;
 namespace cv {
 namespace v4d {
 /*!
- * In general please refere to https://github.com/memononen/nanovg/blob/master/src/nanovg.h for reference.
+ * In general please refer to https://github.com/memononen/nanovg/blob/master/src/nanovg.h for reference.
  */
 namespace nvg {
 /*!
diff --git a/modules/v4d/include/opencv2/v4d/v4d.hpp b/modules/v4d/include/opencv2/v4d/v4d.hpp
index 107096952..6ab468194 100644
--- a/modules/v4d/include/opencv2/v4d/v4d.hpp
+++ b/modules/v4d/include/opencv2/v4d/v4d.hpp
@@ -25,14 +25,18 @@
 #include "source.hpp"
 #include "sink.hpp"
 #include "util.hpp"
+#include "formhelper.hpp"
+#include "nvg.hpp"
+#include "detail/threadpool.hpp"
+
 #include <iostream>
 #include <future>
 #include <set>
 #include <string>
+
 #include <opencv2/imgproc.hpp>
 #include <opencv2/videoio.hpp>
-#include "formhelper.hpp"
-#include "detail/threadpool.hpp"
+
 
 using std::cout;
 using std::cerr;
@@ -49,7 +53,7 @@ namespace nanogui {
  */
 namespace cv {
 /*!
- * Visualization namespace
+ * V4D namespace
  */
 namespace v4d {
 class FormHelper;
@@ -63,12 +67,6 @@ class GLContext;
 class NanoVGContext;
 class NanoguiContext;
 
-/*!
- * The GFLW error callback.
- * @param error Error number
- * @param description Error description
- */
-void glfw_error_callback(int error, const char* description);
 /*!
  * Find widgets that are of type T.
  * @tparam T The type of widget to find
@@ -96,10 +94,7 @@ CV_EXPORTS cv::Scalar colorConvert(const cv::Scalar& src, cv::ColorConversionCod
 
 using namespace cv::v4d::detail;
 
-class NVG;
-
 class CV_EXPORTS V4D {
-    friend class detail::NanoVGContext;
     friend class detail::FrameBufferContext;
     friend class HTML5Capture;
     cv::Size initialSize_;
@@ -347,12 +342,12 @@ public:
      * Enable/Disable scaling the framebuffer during blitting.
      * @param s if true enable scaling
      */
-    CV_EXPORTS void setFrameBufferScaling(bool s);
+    CV_EXPORTS void setScaling(bool s);
     /*!
      * Determine if framebuffer is scaled during blitting.
      * @return true if framebuffer is scaled during blitting.
      */
-    CV_EXPORTS bool isFrameBufferScaling();
+    CV_EXPORTS bool isScaling();
     /*!
      * Everytime a frame is displayed this count is incremented
      * @return the current frame count
@@ -378,15 +373,16 @@ public:
     CV_EXPORTS void printSystemInfo();
 
     CV_EXPORTS void makeCurrent();
-    NanoguiContext& nguiCtx();
+
+    void setDefaultKeyboardEventCallback();
+    void setKeyboardEventCallback(
+            std::function<bool(int key, int scancode, int action, int modifiers)> fn);
 private:
     V4D(const cv::Size& size, const cv::Size& fbsize,
             const string& title, bool offscreen, bool debug, bool compat, int samples);
 
     void init();
-    void setDefaultKeyboardEventCallback();
-    void setKeyboardEventCallback(
-            std::function<bool(int key, int scancode, int action, int modifiers)> fn);
+
     void setMouseDrag(bool d);
     bool isMouseDrag();
     cv::Vec2f getMousePosition();
@@ -397,6 +393,7 @@ private:
     CLVAContext& clvaCtx();
     NanoVGContext& nvgCtx();
     GLContext& glCtx();
+    NanoguiContext& nguiCtx();
 
     bool hasFbCtx();
     bool hasClvaCtx();
@@ -410,6 +407,5 @@ private:
 }
 } /* namespace kb */
 
-#include <opencv2/v4d/nvg.hpp>
 
 #endif /* SRC_OPENCV_V4D_V4D_HPP_ */
diff --git a/modules/v4d/samples/beauty-demo.cpp b/modules/v4d/samples/beauty-demo.cpp
index ceda162fb..5cfae4bea 100644
--- a/modules/v4d/samples/beauty-demo.cpp
+++ b/modules/v4d/samples/beauty-demo.cpp
@@ -26,8 +26,8 @@ constexpr long unsigned int HEIGHT = 720;
 constexpr long unsigned int WIDTH = 960;
 constexpr long unsigned int HEIGHT = 540;
 #endif
-constexpr unsigned int DOWNSIZE_WIDTH = 320;
-constexpr unsigned int DOWNSIZE_HEIGHT = 180;
+constexpr unsigned int DOWNSIZE_WIDTH = 960;
+constexpr unsigned int DOWNSIZE_HEIGHT = 540;
 constexpr bool OFFSCREEN = false;
 #ifndef __EMSCRIPTEN__
 constexpr const char *OUTPUT_FILENAME = "beauty-demo.mkv";
@@ -35,10 +35,10 @@ constexpr const char *OUTPUT_FILENAME = "beauty-demo.mkv";
 const unsigned long DIAG = hypot(double(WIDTH), double(HEIGHT));
 
 /* Visualization parameters */
-constexpr int BLUR_DIV = 1000;
+constexpr int BLUR_DIV = 500;
 int blur_skin_kernel_size = std::max(int(DIAG / BLUR_DIV % 2 == 0 ? DIAG / BLUR_DIV + 1 : DIAG / BLUR_DIV), 1);
 //Saturation boost factor for eyes and lips
-float eyes_and_lips_saturation = 1.6f;
+float eyes_and_lips_saturation = 2.0f;
 //Saturation boost factor for skin
 float skin_saturation = 1.7f;
 //Contrast factor skin
@@ -46,11 +46,11 @@ float skin_contrast = 0.7f;
 #ifndef __EMSCRIPTEN__
 //Show input and output side by side
 bool side_by_side = true;
-//Stretch the video to the window size
-bool stretch = true;
+//Scale the video to the window size
+bool scale = true;
 #else
 bool side_by_side = false;
-bool stretch = false;
+bool scale = false;
 #endif
 
 cv::Ptr<cv::v4d::V4D> window;
@@ -126,7 +126,7 @@ struct FaceFeatures {
         return allPoints;
     }
 
-    //Returns all face features points in fixed order
+    //Returns all feature points in fixed order
     vector<vector<cv::Point2f>> features() const {
         return {chin_,
             top_nose_,
@@ -206,10 +206,10 @@ static void setup_gui(cv::Ptr<cv::v4d::V4D> v) {
 
         form.makeGroup("Display");
         form.makeFormVariable("Side by side", side_by_side, "Enable or disable side by side view");
-        auto* stretchVar = form.makeFormVariable("Stretch", stretch, "Enable or disable stetching to the window size");
-        stretchVar->set_callback([=](const bool& b) {
-            v->setFrameBufferScaling(b);
-            stretch = b;
+        auto* scaleVar = form.makeFormVariable("Stretch", scale, "Enable or disable stetching to the window size");
+        scaleVar->set_callback([=](const bool& b) {
+            v->setScaling(b);
+            scale = b;
         });
 
 #ifndef __EMSCRIPTEN__
@@ -398,7 +398,7 @@ int main() {
     window = V4D::make(cv::Size(WIDTH, HEIGHT), cv::Size(), "Beauty Demo", OFFSCREEN);
     facemark->loadModel("assets/lbfmodel.yaml");
 
-    window->setFrameBufferScaling(stretch);
+    window->setScaling(scale);
 
     if (!OFFSCREEN) {
         setup_gui(window);
diff --git a/modules/v4d/samples/optflow-demo.cpp b/modules/v4d/samples/optflow-demo.cpp
index 9c6cc202a..55d9b5473 100644
--- a/modules/v4d/samples/optflow-demo.cpp
+++ b/modules/v4d/samples/optflow-demo.cpp
@@ -100,7 +100,7 @@ nanogui::Color effect_color(1.0f, 0.75f, 0.4f, 1.0f);
 //display on-screen FPS
 bool show_fps = true;
 //Stretch frame buffer to window size
-bool stretch = false;
+bool scale = false;
 //Use OpenCL or not
 bool use_acceleration = true;
 //The post processing mode
@@ -379,8 +379,8 @@ static void setup_gui(cv::Ptr<cv::v4d::V4D> main, cv::Ptr<cv::v4d::V4D> menu) {
 
         form.makeGroup("Display");
         form.makeFormVariable("Show FPS", show_fps, "Enable or disable the On-screen FPS display");
-        form.makeFormVariable("Stetch", stretch, "Stretch the frame buffer to the window size")->set_callback([=](const bool &s) {
-            main->setFrameBufferScaling(s);
+        form.makeFormVariable("Stetch", scale, "Stretch the frame buffer to the window size")->set_callback([=](const bool &s) {
+            main->setScaling(s);
         });
 
 #ifndef __EMSCRIPTEN__
diff --git a/modules/v4d/src/detail/framebuffercontext.cpp b/modules/v4d/src/detail/framebuffercontext.cpp
index 2ea6f7970..eecabf149 100644
--- a/modules/v4d/src/detail/framebuffercontext.cpp
+++ b/modules/v4d/src/detail/framebuffercontext.cpp
@@ -22,6 +22,10 @@ namespace cv {
 namespace v4d {
 namespace detail {
 
+void glfw_error_callback(int error, const char* description) {
+    fprintf(stderr, "GLFW Error: (%d) %s\n", error, description);
+}
+
 static bool contains_absolute(nanogui::Widget* w, const nanogui::Vector2i& p) {
     nanogui::Vector2i d = p - w->absolute_position();
     return d.x() >= 0 && d.y() >= 0 && d.x() < w->size().x() && d.y() < w->size().y();
@@ -211,7 +215,7 @@ void FrameBufferContext::init() {
 #endif
     if (glfwInit() != GLFW_TRUE)
            assert(false);
-    glfwSetErrorCallback(cv::v4d::glfw_error_callback);
+    glfwSetErrorCallback(cv::v4d::detail::glfw_error_callback);
 
     if (debug_)
         glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GLFW_TRUE);
diff --git a/modules/v4d/src/detail/nanoguicontext.hpp b/modules/v4d/src/detail/nanoguicontext.hpp
index 697dc6bd8..66db418dc 100644
--- a/modules/v4d/src/detail/nanoguicontext.hpp
+++ b/modules/v4d/src/detail/nanoguicontext.hpp
@@ -6,6 +6,7 @@
 #ifndef SRC_OPENCV_NANOGUICONTEXT_HPP_
 #define SRC_OPENCV_NANOGUICONTEXT_HPP_
 
+#include "opencv2/v4d/nvg.hpp"
 #include "framebuffercontext.hpp"
 
 
diff --git a/modules/v4d/src/v4d.cpp b/modules/v4d/src/v4d.cpp
index b956ee390..f4472e76b 100644
--- a/modules/v4d/src/v4d.cpp
+++ b/modules/v4d/src/v4d.cpp
@@ -15,11 +15,6 @@
 
 namespace cv {
 namespace v4d {
-namespace detail {
-void glfw_error_callback(int error, const char* description) {
-    fprintf(stderr, "GLFW Error: (%d) %s\n", error, description);
-}
-}
 
 cv::Scalar colorConvert(const cv::Scalar& src, cv::ColorConversionCodes code) {
     cv::Mat tmpIn(1, 1, CV_8UC3);
@@ -464,11 +459,11 @@ void V4D::setVisible(bool v) {
     nguiCtx().screen().perform_layout();
 }
 
-void V4D::setFrameBufferScaling(bool s) {
+void V4D::setScaling(bool s) {
     stretch_ = s;
 }
 
-bool V4D::isFrameBufferScaling() {
+bool V4D::isScaling() {
     return stretch_;
 }
 
@@ -494,7 +489,7 @@ void V4D::setDefaultKeyboardEventCallback() {
 void V4D::swapContextBuffers() {
     run_sync_on_main<10>([this]() {
         FrameBufferContext::GLScope glScope(glCtx().fbCtx(), GL_READ_FRAMEBUFFER);
-        glCtx().fbCtx().blitFrameBufferToScreen(viewport(), glCtx().fbCtx().getWindowSize(), isFrameBufferScaling());
+        glCtx().fbCtx().blitFrameBufferToScreen(viewport(), glCtx().fbCtx().getWindowSize(), isScaling());
 #ifndef __EMSCRIPTEN__
         glfwSwapBuffers(glCtx().fbCtx().getGLFWWindow());
 #else
@@ -504,7 +499,7 @@ void V4D::swapContextBuffers() {
 
     run_sync_on_main<11>([this]() {
         FrameBufferContext::GLScope glScope(nvgCtx().fbCtx(), GL_READ_FRAMEBUFFER);
-        nvgCtx().fbCtx().blitFrameBufferToScreen(viewport(), nvgCtx().fbCtx().getWindowSize(), isFrameBufferScaling());
+        nvgCtx().fbCtx().blitFrameBufferToScreen(viewport(), nvgCtx().fbCtx().getWindowSize(), isScaling());
 #ifndef __EMSCRIPTEN__
         glfwSwapBuffers(nvgCtx().fbCtx().getGLFWWindow());
 #else
@@ -514,7 +509,7 @@ void V4D::swapContextBuffers() {
 
     run_sync_on_main<12>([this]() {
         FrameBufferContext::GLScope glScope(nguiCtx().fbCtx(), GL_READ_FRAMEBUFFER);
-        nguiCtx().fbCtx().blitFrameBufferToScreen(viewport(), nguiCtx().fbCtx().getWindowSize(), isFrameBufferScaling());
+        nguiCtx().fbCtx().blitFrameBufferToScreen(viewport(), nguiCtx().fbCtx().getWindowSize(), isScaling());
 #ifndef __EMSCRIPTEN__
         glfwSwapBuffers(nguiCtx().fbCtx().getGLFWWindow());
 #else
@@ -539,7 +534,7 @@ bool V4D::display() {
         run_sync_on_main<6>([&, this](){
             {
                FrameBufferContext::GLScope glScope(fbCtx(), GL_READ_FRAMEBUFFER);
-               fbCtx().blitFrameBufferToScreen(viewport(), fbCtx().getWindowSize(), isFrameBufferScaling());
+               fbCtx().blitFrameBufferToScreen(viewport(), fbCtx().getWindowSize(), isScaling());
             }
 #ifndef __EMSCRIPTEN__
             nguiCtx().render(printFPS_, showFPS_);
diff --git a/modules/v4d/tutorials/00-intro.markdown b/modules/v4d/tutorials/00-intro.markdown
index 3ebaa4689..e2c78818d 100644
--- a/modules/v4d/tutorials/00-intro.markdown
+++ b/modules/v4d/tutorials/00-intro.markdown
@@ -114,6 +114,15 @@ make -j8
 sudo make install
 ```
 
+## Download models
+```bash
+mkdir assets
+cd assets
+wget https://github.com/kurnianggoro/GSOC2017/raw/master/data/lbfmodel.yaml
+wget https://github.com/opencv/opencv_zoo/raw/main/models/face_detection_yunet/face_detection_yunet_2023mar.onnx
+cd ..
+```
+
 ## Download the example videos
 ```bash
 # big buck bunny video