预处理

改进来自低质量扫描和照片的输入。使用我们的预处理滤波器清理、拉直和增强困难图像，以获得最佳OCR准确性。

输入色彩校正过滤器

二值化

直接在 IronOCR 中轻松对输入内容进行二值化处理，将图像转化为清晰的黑白版本。该过滤器能有效地将文本从复杂的背景中分离出来，减少噪点，使文本提取更容易、更可靠。

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply binarize affect
imageInput.Binarize();

// Export the modified image
imageInput.SaveAsImages("binarize.jpg");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply binarize affect
imageInput.Binarize();

// Export the modified image
imageInput.SaveAsImages("binarize.jpg");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")

    ' Apply binarize affect
    imageInput.Binarize()

    ' Export the modified image
    imageInput.SaveAsImages("binarize.jpg")
End Using

灰度

将彩色图像转换为灰度图像--这是为更高级的预处理过滤器准备图像的关键步骤。

了解如何：在 .NET C# 中修复图像颜色以便阅读

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply grayscale affect
imageInput.ToGrayScale();

// Export the modified image
imageInput.SaveAsImages("grayscale.jpg");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply grayscale affect
imageInput.ToGrayScale();

// Export the modified image
imageInput.SaveAsImages("grayscale.jpg");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")

    ' Apply grayscale affect
    imageInput.ToGrayScale()

    ' Export the modified image
    imageInput.SaveAsImages("grayscale.jpg")
End Using

更改像素颜色

替换图像中的特定颜色范围，允许您在 OCR 之前去除水印、彩色背景或其他干扰元素。

了解如何：在 .NET C# 中修复图像颜色以便阅读

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");
IronSoftware.Drawing.Color currentColor = new IronSoftware.Drawing.Color("#DB645C");
IronSoftware.Drawing.Color newColor = IronSoftware.Drawing.Color.DarkCyan;

// Replace color
imageInput.ReplaceColor(currentColor, newColor, 80);

// Export the modified image
imageInput.SaveAsImages("replaceColor");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");
IronSoftware.Drawing.Color currentColor = new IronSoftware.Drawing.Color("#DB645C");
IronSoftware.Drawing.Color newColor = IronSoftware.Drawing.Color.DarkCyan;

// Replace color
imageInput.ReplaceColor(currentColor, newColor, 80);

// Export the modified image
imageInput.SaveAsImages("replaceColor");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")
    Dim currentColor As New IronSoftware.Drawing.Color("#DB645C")
    Dim newColor As IronSoftware.Drawing.Color = IronSoftware.Drawing.Color.DarkCyan

    ' Replace color
    imageInput.ReplaceColor(currentColor, newColor, 80)

    ' Export the modified image
    imageInput.SaveAsImages("replaceColor")
End Using

输入形态操作

膨胀

加粗图像中的字符，这有助于连接文本中的断线，提高对模糊或细小字体的识别能力。

了解如何：使用阅读过滤器纠正图像

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply Dilate filter
imageInput.Dilate();

// Export filtered image
imageInput.SaveAsImages("dilate.jpg");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply Dilate filter
imageInput.Dilate();

// Export filtered image
imageInput.SaveAsImages("dilate.jpg");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")

    ' Apply Dilate filter
    imageInput.Dilate()

    ' Export filtered image
    imageInput.SaveAsImages("dilate.jpg")
End Using

腐蚀

将图像中的字符变细，用于分隔相互接触或融合在一起的字符。

了解如何：使用阅读过滤器纠正图像

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply Erode filter
imageInput.Erode();

// Export filtered image
imageInput.SaveAsImages("erode.jpg");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply Erode filter
imageInput.Erode();

// Export filtered image
imageInput.SaveAsImages("erode.jpg");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")

    ' Apply Erode filter
    imageInput.Erode()

    ' Export filtered image
    imageInput.SaveAsImages("erode.jpg")
End Using

更改像素颜色

替换图像中的特定颜色范围，允许您在 OCR 之前去除水印、彩色背景或其他干扰元素。

了解如何：在 .NET C# 中修复图像颜色以便阅读

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");
IronSoftware.Drawing.Color currentColor = new IronSoftware.Drawing.Color("#DB645C");
IronSoftware.Drawing.Color newColor = IronSoftware.Drawing.Color.DarkCyan;

// Replace color
imageInput.ReplaceColor(currentColor, newColor, 80);

// Export the modified image
imageInput.SaveAsImages("replaceColor");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");
IronSoftware.Drawing.Color currentColor = new IronSoftware.Drawing.Color("#DB645C");
IronSoftware.Drawing.Color newColor = IronSoftware.Drawing.Color.DarkCyan;

// Replace color
imageInput.ReplaceColor(currentColor, newColor, 80);

// Export the modified image
imageInput.SaveAsImages("replaceColor");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")
    Dim currentColor As New IronSoftware.Drawing.Color("#DB645C")
    Dim newColor As IronSoftware.Drawing.Color = IronSoftware.Drawing.Color.DarkCyan

    ' Replace color
    imageInput.ReplaceColor(currentColor, newColor, 80)

    ' Export the modified image
    imageInput.SaveAsImages("replaceColor")
End Using

输入方向操作

去倾斜

自动检测和校正倾斜的图像，大幅提高不完美扫描图像的 OCR 精确度。

了解如何：在.NET C#中为阅读修正图像方向

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("paragraph_skewed.png");

// Apply Deskew filter
imageInput.Deskew();

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("paragraph_skewed.png");

// Apply Deskew filter
imageInput.Deskew();

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("paragraph_skewed.png")
    ' Apply Deskew filter
    imageInput.Deskew()
End Using

轮换

以编程方式任意旋转图像，以确保文本在 OCR 引擎中的正确方向。

了解如何：在.NET C#中为阅读修正图像方向

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("paragraph_skewed.png");

// Rotate the image 180 degrees clockwise
imageInput.Rotate(180);

// Export the modified image
imageInput.SaveAsImages("rotate");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("paragraph_skewed.png");

// Rotate the image 180 degrees clockwise
imageInput.Rotate(180);

// Export the modified image
imageInput.SaveAsImages("rotate");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput = New OcrImageInput("paragraph_skewed.png")

    ' Rotate the image 180 degrees clockwise
    imageInput.Rotate(180)

    ' Export the modified image
    imageInput.SaveAsImages("rotate")
End Using

检测方向

自动确定页面方向（0、90、180、270 度），有助于在 OCR 之前进行方向校正。即使文档被颠倒扫描，也能确保高准确性。

了解如何：检测页面旋转

using IronOcr;

using var input = new OcrInput();

// Load PDF document
input.LoadPdf("Clockwise90.pdf");

// Detect page rotation
var results = input.DetectPageOrientation();

// Ouput result
foreach(var result in results)
{
    Console.WriteLine(result.PageNumber);
    Console.WriteLine(result.HighConfidence);
    Console.WriteLine(result.RotationAngle);
}

using IronOcr;

using var input = new OcrInput();

// Load PDF document
input.LoadPdf("Clockwise90.pdf");

// Detect page rotation
var results = input.DetectPageOrientation();

// Ouput result
foreach(var result in results)
{
    Console.WriteLine(result.PageNumber);
    Console.WriteLine(result.HighConfidence);
    Console.WriteLine(result.RotationAngle);
}

Imports IronOcr

Dim Input As New OcrInput()

' Load PDF document
Input.LoadPdf("Clockwise90.pdf")

' Detect page rotation
Dim Results = Input.DetectPageOrientation()

' Output result
For Each Result In Results
    Console.WriteLine(Result.PageNumber)
    Console.WriteLine(Result.HighConfidence)
    Console.WriteLine(Result.RotationAngle)
Next

输入分辨率控制

规模

将图像调整到 OCR 的最佳分辨率，显著提高低分辨率源文件的准确性。

了解如何：在.NET C#中为阅读修正图像方向

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("paragraph_skewed.png");

// Apply scale
imageInput.Scale(70);

// Export the modified image
imageInput.SaveAsImages("rotate");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("paragraph_skewed.png");

// Apply scale
imageInput.Scale(70);

// Export the modified image
imageInput.SaveAsImages("rotate");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("paragraph_skewed.png")
    ' Apply scale
    imageInput.Scale(70)

    ' Export the modified image
    imageInput.SaveAsImages("rotate")
End Using

DPI 设置

对于缺少元数据的低分辨率图像或扫描件，手动设置每英寸点数 (DPI)。提供 DPI 值可引导 OCR 引擎并显著提高识别质量。

了解如何：C# Tesseract Image DPI

using IronOcr;
using System;

var ocrTesseract = new IronTesseract();
using var ocrInput = new OcrInput();
ocrInput.TargetDPI = 300;
ocrInput.LoadImage(@"images\image.png");
var ocrResult = ocrTesseract.Read(ocrInput);
Console.WriteLine(ocrResult.Text);

using IronOcr;
using System;

var ocrTesseract = new IronTesseract();
using var ocrInput = new OcrInput();
ocrInput.TargetDPI = 300;
ocrInput.LoadImage(@"images\image.png");
var ocrResult = ocrTesseract.Read(ocrInput);
Console.WriteLine(ocrResult.Text);

Imports IronOcr
Imports System

Dim ocrTesseract = New IronTesseract()
Using ocrInput = New OcrInput()
    ocrInput.TargetDPI = 300
    ocrInput.LoadImage("images\image.png")
    Dim ocrResult = ocrTesseract.Read(ocrInput)
    Console.WriteLine(ocrResult.Text)
End Using

增强分辨率

通过算法提高低分辨率图像的清晰度，将文字从模糊或像素化的输入中解救出来。

了解如何：使用阅读过滤器纠正图像

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply enhance resolution filter
imageInput.EnhanceResolution();

// Export filtered image
imageInput.SaveAsImages("sharpen.jpg");

using IronOcr;

// Instantiate IronTesseract
IronTesseract ocrTesseract = new IronTesseract();

// Add image
using var imageInput = new OcrImageInput("sample.jpg");

// Apply enhance resolution filter
imageInput.EnhanceResolution();

// Export filtered image
imageInput.SaveAsImages("sharpen.jpg");

Imports IronOcr

' Instantiate IronTesseract
Dim ocrTesseract As New IronTesseract()

' Add image
Using imageInput As New OcrImageInput("sample.jpg")
    ' Apply enhance resolution filter
    imageInput.EnhanceResolution()
    
    ' Export filtered image
    imageInput.SaveAsImages("sharpen.jpg")
End Using

过滤器向导

使用单一的智能方法应用经过精心策划的预处理过滤器链。过滤器向导会自动分析输入的图像，并应用最佳的修正序列，以获得最佳的 OCR 结果。

了解如何：过滤向导

using IronOcr;

var ocrTesseract = new IronTesseract();

// WIZARD - If you are unsure which filters to use,
// use the debug-wizard to test all combinations:
string codeToRun = OcrInputFilterWizard.Run(@"images\image.png", out double confidence, ocrTesseract);
Console.WriteLine($"Confidence: {confidence}");
Console.WriteLine(codeToRun);

using IronOcr;

var ocrTesseract = new IronTesseract();

// WIZARD - If you are unsure which filters to use,
// use the debug-wizard to test all combinations:
string codeToRun = OcrInputFilterWizard.Run(@"images\image.png", out double confidence, ocrTesseract);
Console.WriteLine($"Confidence: {confidence}");
Console.WriteLine(codeToRun);

Imports IronOcr

Dim ocrTesseract = New IronTesseract()

' WIZARD - If you are unsure which filters to use,
' use the debug-wizard to test all combinations:
Dim confidence As Double
Dim codeToRun As String = OcrInputFilterWizard.Run("images\image.png", confidence, ocrTesseract)
Console.WriteLine($"Confidence: {confidence}")
Console.WriteLine(codeToRun)

OCR 图像的一个区域

只针对图像中包含文本的特定区域，节省处理时间。只需定义一个矩形区域，即可从表单、表格或杂乱的背景中分离并提取文本。

了解如何：在 C# 中使用 Tesseract OCR 识别图像的特定区域

using IronOcr;
using IronSoftware.Drawing;

var ocrTesseract = new IronTesseract();
using var ocrInput = new OcrInput();
var ContentArea = new Rectangle(x: 215, y: 1250, width: 1335, height: 280);
ocrInput.LoadImage("img/example.png", ContentArea);
var ocrResult = ocrTesseract.Read(ocrInput);
Console.WriteLine(ocrResult.Text);

using IronOcr;
using IronSoftware.Drawing;

var ocrTesseract = new IronTesseract();
using var ocrInput = new OcrInput();
var ContentArea = new Rectangle(x: 215, y: 1250, width: 1335, height: 280);
ocrInput.LoadImage("img/example.png", ContentArea);
var ocrResult = ocrTesseract.Read(ocrInput);
Console.WriteLine(ocrResult.Text);

Imports IronOcr
Imports IronSoftware.Drawing

Dim ocrTesseract = New IronTesseract()
Using ocrInput = New OcrInput()
    Dim ContentArea = New Rectangle(x:=215, y:=1250, width:=1335, height:=280)
    ocrInput.LoadImage("img/example.png", ContentArea)
    Dim ocrResult = ocrTesseract.Read(ocrInput)
    Console.WriteLine(ocrResult.Text)
End Using