.NET MAUI OCR Using IronOCR

Prerequisites

For creating an OCR app in .NET MAUI, these are the prerequisites:

1. Visual Studio 2022 (Latest version)
2. .NET 6 or 7
3. MAUI packages installed in Visual Studio
4. A .NET MAUI project running in Visual Studio

Install IronOCR

The first step is to install the IronOCR library using the NuGet Package Manager Console. Open the NuGet Package Manager Console by right-clicking on the solution explorer and executing the following command to install the IronOCR library:

Install-Package IronOcr

Frontend Design

We will design the frontend of the application in this section. Open the MainPage.xaml file.

MainPage.xaml

We designate a button that will help us select the image or PDF document for OCR. The button's Clicked property is set to execute the IOCR function which we will define in the next section.

<Button
    x:Name="OCR"
    Text="Click to OCR"
    Clicked="IOCR"
    HorizontalOptions="Center" />

<Button
    x:Name="OCR"
    Text="Click to OCR"
    Clicked="IOCR"
    HorizontalOptions="Center" />

Here, we create an Image element with the name OCRImage. This image box will display the selected file.

<Image
    x:Name="OCRImage"
    SemanticProperties.Description="Selected Image"
    HeightRequest="300"
    HorizontalOptions="Center" />

<Image
    x:Name="OCRImage"
    SemanticProperties.Description="Selected Image"
    HeightRequest="300"
    HorizontalOptions="Center" />

Next, we create an Editor control. It will be used to show the extracted text from the image or PDF document.

<Editor
    x:Name="outputText"
    HorizontalOptions="Center"
    WidthRequest="600"
    HeightRequest="300" />

<Editor
    x:Name="outputText"
    HorizontalOptions="Center"
    WidthRequest="600"
    HeightRequest="300" />

Here is the completed XAML User Interface markup.

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="IronOCR_MAUI_Test.MainPage">

    <ScrollView>
        <VerticalStackLayout
            Spacing="25"
            Padding="30,0"
            VerticalOptions="Center">
            <Button
                x:Name="OCR"
                Text="Click to OCR"
                Clicked="IOCR"
                HorizontalOptions="Center" />
            <Image
                x:Name="OCRImage"
                SemanticProperties.Description="Selected Image"
                HeightRequest="300"
                HorizontalOptions="Center" />

            <Editor
                x:Name="outputText"
                HorizontalOptions="Center"
                WidthRequest="600"
                HeightRequest="300" />
        </VerticalStackLayout>
    </ScrollView>

</ContentPage>

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="IronOCR_MAUI_Test.MainPage">

    <ScrollView>
        <VerticalStackLayout
            Spacing="25"
            Padding="30,0"
            VerticalOptions="Center">
            <Button
                x:Name="OCR"
                Text="Click to OCR"
                Clicked="IOCR"
                HorizontalOptions="Center" />
            <Image
                x:Name="OCRImage"
                SemanticProperties.Description="Selected Image"
                HeightRequest="300"
                HorizontalOptions="Center" />

            <Editor
                x:Name="outputText"
                HorizontalOptions="Center"
                WidthRequest="600"
                HeightRequest="300" />
        </VerticalStackLayout>
    </ScrollView>

</ContentPage>

Now, it's time to write the code for OCR functionality.

Code for OCR using IronOCR

Open the MainPage.xaml.cs class file and write the following function:

MainPage.xaml.cs

private async void IOCR(object sender, EventArgs e)
{
    // Prompt user to select an image using FilePicker
    var images = await FilePicker.Default.PickAsync(new PickOptions
    {
        PickerTitle = "Pick image",
        FileTypes = FilePickerFileType.Images
    });

    // Get the full path of the selected image
    var path = images.FullPath.ToString();

    // Display the selected image in the Image control
    OCRImage.Source = path;

    // Create an IronTesseract object to perform OCR
    var ocr = new IronTesseract();

    // Perform OCR and extract text from the selected image
    using (var input = new OcrInput())
    {
        input.AddImage(path); // Add image to the OCR input
        OcrResult result = ocr.Read(input); // Perform OCR
        string text = result.Text; // Extract text

        // Display extracted text in the Editor control
        outputText.Text = text; 
    }
}

private async void IOCR(object sender, EventArgs e)
{
    // Prompt user to select an image using FilePicker
    var images = await FilePicker.Default.PickAsync(new PickOptions
    {
        PickerTitle = "Pick image",
        FileTypes = FilePickerFileType.Images
    });

    // Get the full path of the selected image
    var path = images.FullPath.ToString();

    // Display the selected image in the Image control
    OCRImage.Source = path;

    // Create an IronTesseract object to perform OCR
    var ocr = new IronTesseract();

    // Perform OCR and extract text from the selected image
    using (var input = new OcrInput())
    {
        input.AddImage(path); // Add image to the OCR input
        OcrResult result = ocr.Read(input); // Perform OCR
        string text = result.Text; // Extract text

        // Display extracted text in the Editor control
        outputText.Text = text; 
    }
}

Private Async Sub IOCR(ByVal sender As Object, ByVal e As EventArgs)
	' Prompt user to select an image using FilePicker
	Dim images = Await FilePicker.Default.PickAsync(New PickOptions With {
		.PickerTitle = "Pick image",
		.FileTypes = FilePickerFileType.Images
	})

	' Get the full path of the selected image
	Dim path = images.FullPath.ToString()

	' Display the selected image in the Image control
	OCRImage.Source = path

	' Create an IronTesseract object to perform OCR
	Dim ocr = New IronTesseract()

	' Perform OCR and extract text from the selected image
	Using input = New OcrInput()
		input.AddImage(path) ' Add image to the OCR input
		Dim result As OcrResult = ocr.Read(input) ' Perform OCR
		Dim text As String = result.Text ' Extract text

		' Display extracted text in the Editor control
		outputText.Text = text
	End Using
End Sub

Let's break down the above code:

• The code uses the FilePicker to allow the user to select an image file from the device. The file picker is configured to only allow images.

var images = await FilePicker.Default.PickAsync(new PickOptions
{
    PickerTitle = "Pick image",
    FileTypes = FilePickerFileType.Images
});
var path = images.FullPath.ToString();

var images = await FilePicker.Default.PickAsync(new PickOptions
{
    PickerTitle = "Pick image",
    FileTypes = FilePickerFileType.Images
});
var path = images.FullPath.ToString();

Dim images = Await FilePicker.Default.PickAsync(New PickOptions With {
	.PickerTitle = "Pick image",
	.FileTypes = FilePickerFileType.Images
})
Dim path = images.FullPath.ToString()

• The Image control is set to display the selected image using its file path.

OCRImage.Source = path;

OCRImage.Source = path;

OCRImage.Source = path

• An IronTesseract object is created to perform OCR. The selected image is added to an OcrInput object. The Read method is called to extract text from the image, which is then displayed in the Editor control.

var ocr = new IronTesseract();
using (var input = new OcrInput())
{
    input.AddImage(path);
    OcrResult result = ocr.Read(input);
    string text = result.Text;
    outputText.Text = text; 
}

var ocr = new IronTesseract();
using (var input = new OcrInput())
{
    input.AddImage(path);
    OcrResult result = ocr.Read(input);
    string text = result.Text;
    outputText.Text = text; 
}

Dim ocr = New IronTesseract()
Using input = New OcrInput()
	input.AddImage(path)
	Dim result As OcrResult = ocr.Read(input)
	Dim text As String = result.Text
	outputText.Text = text
End Using