892956: Added sample for Image Enhancement in OCR.

OCR/.NET/Perform-OCR-ImageEnhancement/OCR_ImageEnhancement.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.10.34916.146
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OCR_ImageEnhancement", "OCR_ImageEnhancement\OCR_ImageEnhancement.csproj", "{1E33DBCD-EE59-45C8-A1D9-1DF6B9BDDF5F}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{1E33DBCD-EE59-45C8-A1D9-1DF6B9BDDF5F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1E33DBCD-EE59-45C8-A1D9-1DF6B9BDDF5F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1E33DBCD-EE59-45C8-A1D9-1DF6B9BDDF5F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1E33DBCD-EE59-45C8-A1D9-1DF6B9BDDF5F}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {68D95991-535C-45D7-8135-3B2FFE9934B8}
+	EndGlobalSection
+EndGlobal

OCR/.NET/Perform-OCR-ImageEnhancement/OCR_ImageEnhancement/ImageProcessor.cs

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+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.Processing;
+using SkiaSharp;
+using Syncfusion.OCRProcessor;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace OCR_ImageEnhancement
+{
+    class ImageProcessor : IImageProcessor
+    {
+        public Stream ProcessImage(Stream imageStream)
+        {
+            //Process the image from stream with any third party library and return the processed image.
+            Stream processedImageStream =ConvertToGrayscaleImage(imageStream);
+            return processedImageStream;
+        }
+
+        public Stream EnhanceResolution(Stream imgstream)
+        {
+            var imageStream = new MemoryStream();
+            imgstream.CopyTo(imageStream);
+            SKBitmap bitmap = SKBitmap.Decode(imageStream.ToArray());
+
+            // Create a new SKImageInfo with the same width and height as the original image
+            SKImageInfo info = new SKImageInfo(bitmap.Width, bitmap.Height);
+
+            // Create a new SKSurface with the SKImageInfo
+            using (SKSurface surface = SKSurface.Create(info))
+            {
+                // Get the SKCanvas from the SKSurface
+                SKCanvas canvas = surface.Canvas;
+
+                // Create a new SKPaint for drawing
+                SKPaint paint = new SKPaint();
+
+                // Create a sharpening factor (experiment with different values)
+                float sharpenFactor = 12;
+
+                // Loop through each pixel and apply sharpening
+                for (int x = 1; x < bitmap.Width - 1; x++)
+                {
+                    for (int y = 1; y < bitmap.Height - 1; y++)
+                    {
+                        // Get the pixel values from the surrounding pixels
+                        SKColor center = bitmap.GetPixel(x, y);
+                        SKColor left = bitmap.GetPixel(x - 1, y);
+                        SKColor right = bitmap.GetPixel(x + 1, y);
+                        SKColor top = bitmap.GetPixel(x, y - 1);
+                        SKColor bottom = bitmap.GetPixel(x, y + 1);
+
+                        // Calculate the sharpened pixel value
+                        byte red = Clamp((int)(center.Red + sharpenFactor * (center.Red - (left.Red + right.Red + top.Red + bottom.Red) / 4)));
+                        byte green = Clamp((int)(center.Green + sharpenFactor * (center.Green - (left.Green + right.Green + top.Green + bottom.Green) / 4)));
+                        byte blue = Clamp((int)(center.Blue + sharpenFactor * (center.Blue - (left.Blue + right.Blue + top.Blue + bottom.Blue) / 4)));
+
+                        // Apply the sharpened pixel value
+                        SKColor sharpenedColor = new SKColor(red, green, blue);
+                        paint.Color = sharpenedColor;
+
+                        // Draw a rectangle representing the sharpened pixel
+                        canvas.DrawRect(x, y, 1, 1, paint);
+                    }
+                }
+
+                // Create a new SKImage from the SKSurface
+                SKImage image = surface.Snapshot();
+
+                // Encode the SKImage to a new SKData
+                SKData data = image.Encode(SKEncodedImageFormat.Png, 100);
+                using (var stream1 = System.IO.File.OpenWrite("sharpened1.png"))
+                {
+                    data.SaveTo(stream1);
+                    //  stream.Dispose();
+                }
+                return data.AsStream();
+            }
+        }
+        static byte Clamp(int value)
+        {
+            return (byte)(value < 0 ? 0 : (value > 255 ? 255 : value));
+        }
+        private Stream ConvertToGrayscaleImage(Stream imgstream)
+        {
+            var imageStream = new MemoryStream();
+            imgstream.CopyTo(imageStream);
+            SKBitmap originalBitmap = SKBitmap.Decode(imageStream.ToArray());
+            // Create a new bitmap with the same dimensions as the original
+            SKBitmap grayscaleBitmap = new SKBitmap(originalBitmap.Width, originalBitmap.Height);
+
+            // Iterate through each pixel in the original bitmap
+            for (int x = 0; x < originalBitmap.Width; x++)
+            {
+                for (int y = 0; y < originalBitmap.Height; y++)
+                {
+                    // Get the color of the original pixel
+                    SKColor originalColor = originalBitmap.GetPixel(x, y);
+
+                    // Calculate the grayscale value
+                    byte grayscaleValue = (byte)((originalColor.Red + originalColor.Green + originalColor.Blue) / 3);
+
+                    // Create a new color with the same grayscale value for all channels
+                    SKColor grayscaleColor = new SKColor(grayscaleValue, grayscaleValue, grayscaleValue);
+
+                    // Set the pixel in the new grayscale bitmap
+                    grayscaleBitmap.SetPixel(x, y, grayscaleColor);
+                }
+            }
+
+            // Save or use the grayscale image as needed
+            SKImage grayscaleImage = SKImage.FromBitmap(grayscaleBitmap);
+
+            // Encode and save the image
+            SKData data = grayscaleImage.Encode();
+            return data.AsStream();
+        }
+        private Stream Sixlaborslib(Stream imageStream)
+        {
+            MemoryStream stream = new MemoryStream();
+            using (Image image = Image.Load(imageStream))
+            {
+                image.Mutate(x => x.GaussianSharpen());
+                image.Mutate(x => x.Grayscale());
+                image.Mutate(x => x.BinaryThreshold(0.75f));
+                image.Save(stream, new PngEncoder());
+            }
+            return stream;
+        }
+        private Stream imageBinarization(Stream imgstream)
+        {
+            var imageStream = new MemoryStream();
+            imgstream.CopyTo(imageStream);
+            SKBitmap bitmap = SKBitmap.Decode(imageStream.ToArray());
+
+            // Create a new SKImageInfo with the same width and height as the original image
+            SKImageInfo info = new SKImageInfo(bitmap.Width, bitmap.Height);
+
+            // Create a new SKSurface with the SKImageInfo
+            using (SKSurface surface = SKSurface.Create(info))
+            {
+                // Get the SKCanvas from the SKSurface
+                SKCanvas canvas = surface.Canvas;
+
+                // Create a new SKPaint for drawing
+                SKPaint paint = new SKPaint();
+
+                // Loop through each pixel and apply binarization based on a threshold
+                for (int x = 0; x < bitmap.Width; x++)
+                {
+                    for (int y = 0; y < bitmap.Height; y++)
+                    {
+                        SKColor pixelColor = bitmap.GetPixel(x, y);
+
+                        // Adjust the threshold value based on your needs
+                        int threshold = 205;
+
+                        // Perform binarization
+                        SKColor binarizedColor = (pixelColor.Red + pixelColor.Green + pixelColor.Blue) / 3 > threshold
+                            ? SKColors.White
+                            : SKColors.Black;
+
+                        paint.Color = binarizedColor;
+
+                        // Draw a rectangle representing the binarized pixel
+                        canvas.DrawRect(x, y, 1, 1, paint);
+                    }
+                }
+
+                // Create a new SKImage from the SKSurface
+                SKImage image = surface.Snapshot();
+
+                // Encode the SKImage to a new SKData
+                SKData data = image.Encode(SKEncodedImageFormat.Png, 100);
+
+                return data.AsStream();
+
+            }
+        }
+    }
+}

OCR/.NET/Perform-OCR-ImageEnhancement/OCR_ImageEnhancement/OCR_ImageEnhancement.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.4" />
+    <PackageReference Include="Syncfusion.PDF.OCR.Net.Core" Version="25.2.7" />
+  </ItemGroup>
+
+</Project>

OCR/.NET/Perform-OCR-ImageEnhancement/OCR_ImageEnhancement/Program.cs

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+
+using OCR_ImageEnhancement;
+using Syncfusion.OCRProcessor;
+using Syncfusion.Pdf.Parsing;
+
+
+//Initialize the OCR processor.
+using (OCRProcessor processor = new OCRProcessor())
+{
+    //Load an existing PDF document.
+    FileStream stream = new FileStream("../../../Carte grise Peugeot 108.pdf", FileMode.Open);
+    PdfLoadedDocument document = new PdfLoadedDocument(stream);
+    //Set OCR language.
+    processor.Settings.Language = Languages.English;
+    processor.ImageProcessor = new ImageProcessor();
+    //Perform OCR with input document and tessdata (Language packs).
+    string text = processor.PerformOCR(document, 0, 0, processor.TessDataPath);
+    //Create file stream.
+    using (FileStream outputFileStream = new FileStream("../../../Output.pdf", FileMode.Create, FileAccess.ReadWrite))
+    {
+        //Save the PDF document to file stream.
+        document.Save(outputFileStream);
+    }
+    //Close the document.
+    document.Close(true);
+    File.WriteAllText("../../../Output.txt", text);
+}