C#: extraiga texto de imágenes o archivos PDF escaneados con OCR

Install-Package Spire.PDF

using Spire.OCR;
    using System.IO;
    
    namespace ReadTextFromImage
    {
        internal class Program
        {
            static void Main(string[] args)
            {
                //Specify the path of the input image file
                string imageFilePath = "Image.png";
                //Specify the path of the output text file
                string outputFilePath = "ScanImage.txt";
    
                //Call the ScanTextFromImage method to scan text from an image
                string scannedText = ScanTextFromImage(imageFilePath);
    
                //Write the text to the specified file
                File.WriteAllText(outputFilePath, scannedText);
            }
    
            public static string ScanTextFromImage(string imageFilePath)
            {
                //Instantiate an OcrScanner object
                using (OcrScanner ocrScanner = new OcrScanner())
                {
                    //Scan text from the image
                    ocrScanner.Scan(imageFilePath);
    
                    //Get the recognized text from the OcrScanner object
                    IOCRText text = ocrScanner.Text;
    
                    //Return the text
                    return text.ToString();
                }
            }
        }
    }

using Spire.OCR;
    using System.Collections.Generic;
    using System.IO;
    
    namespace ReadTextFromImageWithCoordinates
    {
        internal class Program
        {
            static void Main(string[] args)
            {
                //Specify the path of the input image file
                string imagePath = "Image.png";
                //Specify the path of the output text file
                string outputFile = "ScanImageWithCoordinates.txt";
    
                //Call the ScanTextFromImageWithCoordinates method to extract text and its area information from the image
                List<string> extractedText = ScanTextFromImageWithCoordinates(imagePath);
    
                //Write the result to the specified file
                File.WriteAllLines(outputFile, extractedText);
            }
    
            //Retrieve the text blocks along with their location information (x, y, width, height) from an image
            public static List<string> ScanTextFromImageWithCoordinates(string imageFilePath)
            {
                //Create a list
                List<string> extractedText = new List<string>();
    
                //Instantiate an OcrScanner object
                using (OcrScanner ocrScanner = new OcrScanner())
                {
                    //Scan text from the image
                    ocrScanner.Scan(imageFilePath);
                    //Get the scanned text
                    IOCRText text = ocrScanner.Text;
    
                    //Iterate through each text block
                    foreach (IOCRTextBlock block in text.Blocks)
                    {
                        //Append the text of each block and its location information to the list
                        extractedText.Add($"Text: {block.Text}\nRectangular Area: {block.Box}");
                    }
                }
    
                return extractedText;
            }
        }
    }

using Spire.OCR;
    using Spire.Pdf;
    using System.Collections.Generic;
    using System.Drawing;
    using System.Drawing.Imaging;
    using System.IO;
    
    namespace ReadTextFromScannedPDF
    {
        internal class Program
        {
            static void Main(string[] args)
            {
                //Specify the path of the scanned PDF file
                string pdfFilePath = "Sample.pdf";
                //Specify the path of the output text file
                string outputFilePath = "ScanPDF.txt";
    
                //Extract text from the scanned PDF
                List<string> extractedText = ExtractTextFromScannedPDF(pdfFilePath);
    
                //Write the text to the specified file
                File.WriteAllLines(outputFilePath, extractedText);
            }
    
            //Extract text from a scanned PDF
            public static List<string> ExtractTextFromScannedPDF(string pdfFilePath)
            {
                //Create a list to store the extracted text
                List<string> extractedText = new List<string>();
    
                //Create an instance of the PdfDocument class
                using (PdfDocument document = new PdfDocument())
                {
                    //Load the PDF document
                    document.LoadFromFile(pdfFilePath);
    
                    //Iterate through each page of the document
                    for (int pageIndex = 0; pageIndex < document.Pages.Count; pageIndex++)
                    {
                        //Convert the page to an image
                        using (Image image = document.SaveAsImage(pageIndex, 300, 300))
                        {
                            //Create a memory stream to hold the image data
                            using (MemoryStream stream = new MemoryStream())
                            {
                                //Save the image to the memory stream in PNG format
                                image.Save(stream, ImageFormat.Png);
                                stream.Position = 0;
    
                                //Scan the text from the image and add it to the list
                                string text = ScanTextFromImageStream(stream);
                                extractedText.Add(text);
                            }
                        }
                    }
                }
    
                //Return the list
                return extractedText;
            }
    
            //Scan text from an image stream
            public static string ScanTextFromImageStream(Stream stream)
            {
                //Create an instance of the OcrScanner class
                using (OcrScanner ocrScanner = new OcrScanner())
                {
                    //Scan the text from the image stream in PNG format
                    ocrScanner.Scan(stream, OCRImageFormat.Png);
                    IOCRText text = ocrScanner.Text;
    
                    //Return the text
                    return text.ToString();
                }
            }
        }
    }