Windows 10 OCR のテストプログラム。 This program is licensed under the GNU General Public License v3.0.

MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Graphics;
using Windows.Graphics.Capture;
using Windows.Graphics.DirectX;
using Windows.UI;
using Windows.UI.Composition;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Hosting;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using Microsoft.Graphics.Canvas;
using Microsoft.Graphics.Canvas.UI.Composition;
using Emgu.CV.Structure;
using Windows.Globalization;
using Windows.Media.Ocr;
using Windows.Graphics.Imaging;
using System.Text;
using Microsoft.Graphics.Canvas.Text;

// https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x804 上介绍了“空白页”项模板

namespace BicehecarayHerekurwuqear
{
    /// <summary>
    /// 可用于自身或导航至 Frame 内部的空白页。
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public Language ocrLanguage = new Language("en-us");
        public OcrEngine ocrEngine = null;

        public MainPage()
        {
            this.InitializeComponent();
            Setup();
            Loaded += MainPage_Loaded;
        }

        private async void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            await StartCaptureAsync();
        }

        private void Setup()
        {
            _canvasDevice = new CanvasDevice();

            var compositionGraphicsDevice = CanvasComposition.CreateCompositionGraphicsDevice(
                Window.Current.Compositor,
                _canvasDevice);

            var compositor = Window.Current.Compositor;

            _surface = compositionGraphicsDevice.CreateDrawingSurface(
                new Size(1000, 600),
                DirectXPixelFormat.B8G8R8A8UIntNormalized,
                DirectXAlphaMode.Premultiplied);
            // 现在只有这个参数能在 Composition 使用
            var visual = compositor.CreateSpriteVisual();
            visual.RelativeSizeAdjustment = Vector2.One;
            var brush = compositor.CreateSurfaceBrush(_surface);
            brush.Stretch = CompositionStretch.Uniform;
            visual.Brush = brush;
            ElementCompositionPreview.SetElementChildVisual(this, visual);

            _compositionGraphicsDevice = compositionGraphicsDevice;

            this.ocrEngine = OcrEngine.TryCreateFromLanguage(ocrLanguage);

            format = new CanvasTextFormat
            {
                FontSize = 10.0f,
                WordWrapping = CanvasWordWrapping.NoWrap
            };
        }

        public async Task StartCaptureAsync()
        {
            // 让用户选择哪个应用
            var picker = new GraphicsCapturePicker();
            GraphicsCaptureItem item = await picker.PickSingleItemAsync();

            // 如果用户有选择一个应用那么这个属性不为空
            if (item != null)
            {
                StartCaptureInternal(item);
            }
        }

        private void StartCaptureInternal(GraphicsCaptureItem item)
        {
            SoftwareBitmap softwareBitmapImg;

            // 下面参数暂时不能修改
            Direct3D11CaptureFramePool framePool = Direct3D11CaptureFramePool.Create(
                _canvasDevice, // D3D device
                DirectXPixelFormat.B8G8R8A8UIntNormalized, // Pixel format
                                                           // 要在其中存储捕获的框架的缓冲区数量
                1,
                // 每个缓冲区大小
                item.Size); // Size of the buffers

            framePool.FrameArrived += async (s, a) =>
            {
                using (var frame = framePool.TryGetNextFrame())
                {
                    try
                    {
                        // 将获取到的 Direct3D11CaptureFrame 转 win2d 的
                        CanvasBitmap canvasBitmap = CanvasBitmap.CreateFromDirect3D11Surface(
                            _canvasDevice,
                            frame.Surface);

                        CanvasComposition.Resize(_surface, canvasBitmap.Size);

                        using (var session = CanvasComposition.CreateDrawingSession(_surface))
                        {
                            //// キャプチャーした画像をOCRでテキスト化
                            softwareBitmapImg =
                                await SoftwareBitmap.CreateCopyFromSurfaceAsync(canvasBitmap);

                            //////// OCRで認識した箇所を描画
                            session.Clear(Colors.Transparent);
                            ////session.DrawImage(canvasBitmap);

                            await this.MyOcr(softwareBitmapImg, canvasBitmap, session);

                            ////var text = await ExtractText(softwareBitmapImg);

                            //// 画面にテキストを表示
                            ////session.DrawText(text, new Vector2(100, 100), Colors.Red);
                        }
                    }
                    catch (Exception e) when (_canvasDevice.IsDeviceLost(e.HResult))
                    {
                        // 设备丢失
                    }
                }
            };

            var captureSession = framePool.CreateCaptureSession(item);
            captureSession.StartCapture();

            // 作为字段防止内存回收
            _direct3D11CaptureFramePool = framePool;
            _graphicsCaptureSession = captureSession;
        }

        private async Task MyOcr(
            SoftwareBitmap softwareBitmapImg, CanvasBitmap canvasBitmap, CanvasDrawingSession session)
        {
            //// OCR
            var oceResult = await DetectAsync(softwareBitmapImg);

            foreach (var line in oceResult.Lines)
            {
                foreach (var word in line.Words)
                {
                    var r = new Rect(
                        word.BoundingRect.X,
                        word.BoundingRect.Y,
                        word.BoundingRect.Width,
                        word.BoundingRect.Height);

                    session.DrawText(
                        word.Text,
                        (float)word.BoundingRect.X,
                        (float)word.BoundingRect.Y - 3,
                        (float)word.BoundingRect.Width,
                        (float)word.BoundingRect.Height,
                        Colors.Red,
                        this.format);
                    session.DrawRectangle(r, Color.FromArgb(255, 255, 0, 0));
                }
            }
        }

        private async Task<OcrResult> DetectAsync(SoftwareBitmap bitmap)
        {
            var ocrResult = await ocrEngine.RecognizeAsync(bitmap);
            return ocrResult;
        }

        private async Task<string> ExtractText(SoftwareBitmap bitmap)
        {
            var ocrResult = await ocrEngine.RecognizeAsync(bitmap);
            var buff = new StringBuilder();
            int len = 100;
            foreach (var c in ocrResult.Text)
            {
                buff.Append(c);
                len++;
                if (len > 50)
                {
                    buff.AppendLine();
                    len = 0;
                }
            }

            var text = buff.ToString();

            return text;
        }

        private CanvasDevice _canvasDevice;
        private CompositionDrawingSurface _surface;

        // 下面属性防止内存回收
        private CompositionGraphicsDevice _compositionGraphicsDevice;
        private Direct3D11CaptureFramePool _direct3D11CaptureFramePool;
        private GraphicsCaptureSession _graphicsCaptureSession;

        private CanvasTextFormat format = null;
    }
}

Windows 10 のOCRサンプルです。
ここにあるOCRサンプルを元に作成したものです。
テスト実行した様子は、この動画を御覧ください。