使用IronOCR裁剪區域和矩形
Curtis Chau
Updated: 2026年6月29日
如何使用IronOCR在PDF上設定內容區域？
內容區域和PDF
OcrInput.LoadPdf 和 LoadPdfPage 方法都可以選擇新增內容區域。
問題 - 如何知道我的內容區域有多大，因為PDF不是以像素為單位，但內容區域通常用它們來測量？
選項 1
OcrInput.TargetDPI 的預設值是225 - 這決定了PDF圖像的像素大小。 IronOCR會讀取這個。
選項 2（理想使用案例）
- 在您的PDF模板中使用
OcrInput.LoadPdf()。 - 使用
OcrInput.GetPages()來獲取輸入的寬度和高度。 - 使用
OcrInput.GetPages().First().ToBitmap()來獲取OCR引擎將讀取的精確圖像。 - 您現在可以從匯出的圖像中以像素測量內容區域。
- 目標坐標可用於特定的OCR區域（參見最終結果）。
要獲取您的資訊：
using System.Linq; // Needed for First()
using IronOcr;
var ocr = new IronTesseract();
using (var input = new OcrInput())
{
// Load the PDF document
input.LoadPdf("example.pdf");
// Save the first page as a bitmap to measure it
input.GetPages().First().ToBitmap().SaveAs("measure-me.bmp");
// Get the dimensions of the first page
var width = input.GetPages().First().Width;
var height = input.GetPages().First().Height;
// Optionally, output the dimensions to understand the scale
Console.WriteLine($"Width: {width}px, Height: {height}px");
}Imports System.Linq ' Needed for First()
Imports IronOcr
Dim ocr As New IronTesseract()
Using input As New OcrInput()
' Load the PDF document
input.LoadPdf("example.pdf")
' Save the first page as a bitmap to measure it
input.GetPages().First().ToBitmap().SaveAs("measure-me.bmp")
' Get the dimensions of the first page
Dim width = input.GetPages().First().Width
Dim height = input.GetPages().First().Height
' Optionally, output the dimensions to understand the scale
Console.WriteLine($"Width: {width}px, Height: {height}px")
End UsingImports System.Linq ' Needed for First()
Imports IronOcr
Dim ocr As New IronTesseract()
Using input As New OcrInput()
' Load the PDF document
input.LoadPdf("example.pdf")
' Save the first page as a bitmap to measure it
input.GetPages().First().ToBitmap().SaveAs("measure-me.bmp")
' Get the dimensions of the first page
Dim width = input.GetPages().First().Width
Dim height = input.GetPages().First().Height
' Optionally, output the dimensions to understand the scale
Console.WriteLine($"Width: {width}px, Height: {height}px")
End Using最終結果：
using IronOcr;
using IronSoftware.Drawing; // Needed for Rectangle
using System;
var ocr = new IronTesseract();
using (var input = new OcrInput())
{
// Define the content area rectangle with specific pixel coordinates
var contentArea = new Rectangle
{
X = 215,
Y = 1250,
Height = 280,
Width = 1335
}; //<-- the area you want in px
// Load the specific content area of the PDF
input.LoadPdf("example.pdf", ContentArea: contentArea);
// Perform OCR on the defined content area
var result = ocr.Read(input);
// Optionally, print the OCR result
Console.WriteLine(result.Text);
}using IronOcr;
using IronSoftware.Drawing; // Needed for Rectangle
using System;
var ocr = new IronTesseract();
using (var input = new OcrInput())
{
// Define the content area rectangle with specific pixel coordinates
var contentArea = new Rectangle
{
X = 215,
Y = 1250,
Height = 280,
Width = 1335
}; //<-- the area you want in px
// Load the specific content area of the PDF
input.LoadPdf("example.pdf", ContentArea: contentArea);
// Perform OCR on the defined content area
var result = ocr.Read(input);
// Optionally, print the OCR result
Console.WriteLine(result.Text);
}Imports IronOcr
Imports IronSoftware.Drawing ' Needed for Rectangle
Dim ocr = New IronTesseract()
Using input = New OcrInput()
' Define the content area rectangle with specific pixel coordinates
Dim contentArea = New Rectangle With {
.X = 215,
.Y = 1250,
.Height = 280,
.Width = 1335
} '<-- the area you want in px
' Load the specific content area of the PDF
input.LoadPdf("example.pdf", ContentArea:=contentArea)
' Perform OCR on the defined content area
Dim result = ocr.Read(input)
' Optionally, print the OCR result
Console.WriteLine(result.Text)
End UsingImports IronOcr
Imports IronSoftware.Drawing ' Needed for Rectangle
Dim ocr = New IronTesseract()
Using input = New OcrInput()
' Define the content area rectangle with specific pixel coordinates
Dim contentArea = New Rectangle With {
.X = 215,
.Y = 1250,
.Height = 280,
.Width = 1335
} '<-- the area you want in px
' Load the specific content area of the PDF
input.LoadPdf("example.pdf", ContentArea:=contentArea)
' Perform OCR on the defined content area
Dim result = ocr.Read(input)
' Optionally, print the OCR result
Console.WriteLine(result.Text)
End UsingAPI Reference: OcrInput | OcrInput.Page
Curtis Chau擁有Carleton大學的電腦科學學士學位，專精於前端開發，擁有Node.js、TypeScript、JavaScript和React的專業知識。Curtis熱衷於建立直觀且美觀的使用者介面，喜愛使用現代框架並建立結構良好、視覺吸引力的手冊。
