iOS OCR库（免费和付费工具比较）

// Simplified — see Sdcb.PaddleOCR documentation for full API
using Sdcb.PaddleOCR;
using Sdcb.PaddleOCR.Models;
using OpenCvSharp;

public class PaddleOcrService
{
    private readonly PaddleOcrAll _ocr;

    public PaddleOcrService()
    {
        // Three separate models, each downloaded independently
        var detModel = LocalFullModels.ChineseV3.DetectionModel;
        var clsModel = LocalFullModels.ChineseV3.ClassifierModel;
        var recModel = LocalFullModels.ChineseV3.RecognitionModel;

        // GPU config: set GpuDeviceId = 0 and install CUDA runtime packages
        _ocr = new PaddleOcrAll(detModel, clsModel, recModel);
    }

    public string ExtractText(string imagePath)
    {
        // OpenCV required for image loading — not System.Drawing
        using var image = Cv2.ImRead(imagePath);
        var result = _ocr.Run(image);

        // Manual sort by position; no automatic reading-order guarantee
        return string.Join("\n", result.Regions
            .OrderBy(r => r.Rect.Center.Y)
            .ThenBy(r => r.Rect.Center.X)
            .Select(r => r.Text));
    }
}

Imports Sdcb.PaddleOCR
Imports Sdcb.PaddleOCR.Models
Imports OpenCvSharp

Public Class PaddleOcrService
    Private ReadOnly _ocr As PaddleOcrAll

    Public Sub New()
        ' Three separate models, each downloaded independently
        Dim detModel = LocalFullModels.ChineseV3.DetectionModel
        Dim clsModel = LocalFullModels.ChineseV3.ClassifierModel
        Dim recModel = LocalFullModels.ChineseV3.RecognitionModel

        ' GPU config: set GpuDeviceId = 0 and install CUDA runtime packages
        _ocr = New PaddleOcrAll(detModel, clsModel, recModel)
    End Sub

    Public Function ExtractText(imagePath As String) As String
        ' OpenCV required for image loading — not System.Drawing
        Using image = Cv2.ImRead(imagePath)
            Dim result = _ocr.Run(image)

            ' Manual sort by position; no automatic reading-order guarantee
            Return String.Join(vbLf, result.Regions _
                .OrderBy(Function(r) r.Rect.Center.Y) _
                .ThenBy(Function(r) r.Rect.Center.X) _
                .Select(Function(r) r.Text))
        End Using
    End Function
End Class

// Simplified — see Sdcb.PaddleOCR documentation for full API
// This is not one line of setup; it represents several coordinated decisions:
// - Which model version to use (ChineseV3, V4, etc.)
// - Whether models are local files or downloaded on first use
// - Which inference backend (CPU, MKL, GPU)
// - Which OpenCvSharp runtime package matches the deployment OS

var detModel = LocalFullModels.ChineseV3.DetectionModel;  // Version-specific
var clsModel = LocalFullModels.ChineseV3.ClassifierModel; // Version-specific
var recModel = LocalFullModels.ChineseV3.RecognitionModel; // Version-specific

var ocr = new PaddleOcrAll(detModel, clsModel, recModel);
// If a newer model format is released, these names and classes may change

' Simplified — see Sdcb.PaddleOCR documentation for full API
' This is not one line of setup; it represents several coordinated decisions:
' - Which model version to use (ChineseV3, V4, etc.)
' - Whether models are local files or downloaded on first use
' - Which inference backend (CPU, MKL, GPU)
' - Which OpenCvSharp runtime package matches the deployment OS

Dim detModel = LocalFullModels.ChineseV3.DetectionModel  ' Version-specific
Dim clsModel = LocalFullModels.ChineseV3.ClassifierModel ' Version-specific
Dim recModel = LocalFullModels.ChineseV3.RecognitionModel ' Version-specific

Dim ocr As New PaddleOcrAll(detModel, clsModel, recModel)
' If a newer model format is released, these names and classes may change

// One package: dotnet add package IronOcr
// 否 model downloads. 否 OpenCV. 否 runtime packages.
IronOcr.License.LicenseKey = "YOUR-LICENSE-KEY";

var result = new IronTesseract().Read("document.jpg");
Console.WriteLine(result.Text);
Console.WriteLine($"Confidence: {result.Confidence}%");

Imports IronOcr

' One package: dotnet add package IronOcr
' 否 model downloads. 否 OpenCV. 否 runtime packages.
IronOcr.License.LicenseKey = "YOUR-LICENSE-KEY"

Dim result = New IronTesseract().Read("document.jpg")
Console.WriteLine(result.Text)
Console.WriteLine($"Confidence: {result.Confidence}%")

// Simplified — see Sdcb.PaddleOCR documentation for full API
// English model set (if available for your version)
// var recModel = LocalFullModels.EnglishV3.RecognitionModel;

// Chinese model set (primary supported use case)
var detModel = LocalFullModels.ChineseV3.DetectionModel;
var recModel = LocalFullModels.ChineseV3.RecognitionModel;
var clsModel = LocalFullModels.ChineseV3.ClassifierModel;

var ocr = new PaddleOcrAll(detModel, clsModel, recModel);
// Non-CJK languages require checking upstream PaddleOCR model availability
// Mixed CJK + Latin in the same document may require model selection decisions

' Simplified — see Sdcb.PaddleOCR documentation for full API
' English model set (if available for your version)
' Dim recModel = LocalFullModels.EnglishV3.RecognitionModel

' Chinese model set (primary supported use case)
Dim detModel = LocalFullModels.ChineseV3.DetectionModel
Dim recModel = LocalFullModels.ChineseV3.RecognitionModel
Dim clsModel = LocalFullModels.ChineseV3.ClassifierModel

Dim ocr = New PaddleOcrAll(detModel, clsModel, recModel)
' Non-CJK languages require checking upstream PaddleOCR model availability
' Mixed CJK + Latin in the same document may require model selection decisions

// dotnet add package IronOcr.Languages.ChineseSimplified
// dotnet add package IronOcr.Languages.French
// dotnet add package IronOcr.Languages.Arabic

var ocr = new IronTesseract();
ocr.Language = OcrLanguage.ChineseSimplified;
ocr.AddSecondaryLanguage(OcrLanguage.English); // Mixed-language document

var result = ocr.Read("mixed-document.jpg");

' dotnet add package IronOcr.Languages.ChineseSimplified
' dotnet add package IronOcr.Languages.French
' dotnet add package IronOcr.Languages.Arabic

Dim ocr As New IronTesseract()
ocr.Language = OcrLanguage.ChineseSimplified
ocr.AddSecondaryLanguage(OcrLanguage.English) ' Mixed-language document

Dim result = ocr.Read("mixed-document.jpg")

// Simplified — see Sdcb.PaddleOCR documentation for full API
// PaddleSharp has no PDF support — pages must be pre-converted to images
// Preprocessing (deskew, denoise) requires OpenCV operations:

using OpenCvSharp;

// Load image via OpenCV
using var image = Cv2.ImRead("scan.jpg");

// Manual grayscale conversion
using var gray = new Mat();
Cv2.CvtColor(image, gray, ColorConversionCodes.BGR2GRAY);

// Manual threshold (binarization)
using var binary = new Mat();
Cv2.Threshold(gray, binary, 128, 255, ThresholdTypes.Binary);

// Then pass to OCR engine
var result = _ocr.Run(binary);
// Each preprocessing step requires OpenCV knowledge
// PDF pages require a separate PDF-to-image conversion step first

Imports OpenCvSharp

' Load image via OpenCV
Using image As Mat = Cv2.ImRead("scan.jpg")

    ' Manual grayscale conversion
    Using gray As New Mat()
        Cv2.CvtColor(image, gray, ColorConversionCodes.BGR2GRAY)

        ' Manual threshold (binarization)
        Using binary As New Mat()
            Cv2.Threshold(gray, binary, 128, 255, ThresholdTypes.Binary)

            ' Then pass to OCR engine
            Dim result = _ocr.Run(binary)
            ' Each preprocessing step requires OpenCV knowledge
            ' PDF pages require a separate PDF-to-image conversion step first
        End Using
    End Using
End Using

using var input = new OcrInput();
input.LoadImage("low-quality-scan.jpg");

// Built-in preprocessing — no OpenCV, no manual image math
input.Deskew();
input.DeNoise();
input.Contrast();
input.Binarize();
input.EnhanceResolution(300);

var result = new IronTesseract().Read(input);
Console.WriteLine(result.Text);

Imports IronOcr

Using input As New OcrInput()
    input.LoadImage("low-quality-scan.jpg")

    ' Built-in preprocessing — no OpenCV, no manual image math
    input.Deskew()
    input.DeNoise()
    input.Contrast()
    input.Binarize()
    input.EnhanceResolution(300)

    Dim result = New IronTesseract().Read(input)
    Console.WriteLine(result.Text)
End Using

// PDF input — no external library, no page conversion
var result = new IronTesseract().Read("scanned-document.pdf");

// Password-protected PDFs
using var input = new OcrInput();
input.LoadPdf("encrypted.pdf", Password: "secret");
var result = new IronTesseract().Read(input);

// Output as searchable PDF
result.SaveAsSearchablePdf("searchable-output.pdf");

Imports IronTesseract

' PDF input — no external library, no page conversion
Dim result = New IronTesseract().Read("scanned-document.pdf")

' Password-protected PDFs
Using input As New OcrInput()
    input.LoadPdf("encrypted.pdf", Password:="secret")
    result = New IronTesseract().Read(input)
End Using

' Output as searchable PDF
result.SaveAsSearchablePdf("searchable-output.pdf")

// PaddleSharp pattern — requires OpenCV
using var image = Cv2.ImRead(imagePath);
var result = _ocr.Run(image);

//IronOCRequivalent — no OpenCV
var result = new IronTesseract().Read(imagePath);

Imports OpenCvSharp
Imports IronOcr

' PaddleSharp pattern — requires OpenCV
Using image = Cv2.ImRead(imagePath)
    Dim result = _ocr.Run(image)
End Using

' IronOCR equivalent — no OpenCV
Dim result = New IronTesseract().Read(imagePath)

var result = new IronTesseract().Read("document.jpg");

// Per-word with position — equivalent to PaddleSharp region enumeration
foreach (var word in result.Words)
{
    Console.WriteLine($"'{word.Text}' at ({word.X},{word.Y}) confidence:{word.Confidence}%");
}

Imports System
Imports IronOcr

Dim result = New IronTesseract().Read("document.jpg")

' Per-word with position — equivalent to PaddleSharp region enumeration
For Each word In result.Words
    Console.WriteLine($"'{word.Text}' at ({word.X},{word.Y}) confidence:{word.Confidence}%")
Next

// dotnet add package IronOcr.Languages.ChineseSimplified

var ocr = new IronTesseract();
ocr.Language = OcrLanguage.ChineseSimplified;
var result = ocr.Read("document.jpg");

Imports IronOcr

Dim ocr As New IronTesseract()
ocr.Language = OcrLanguage.ChineseSimplified
Dim result = ocr.Read("document.jpg")