Save Searchable PDFs in C# with IronOCR

Imports IronOcr

' Create the OCR engine: defaults to English with balanced speed and accuracy
Dim ocrTesseract As New IronTesseract()

' Required: without this flag the text overlay layer is not built, and SaveAsSearchablePdf produces a plain image PDF
ocrTesseract.Configuration.RenderSearchablePdf = True

' Wrap the TIFF in OcrImageInput: handles DPI detection and page layout automatically
Using imageInput As New OcrImageInput("Potter.tiff")
    ' Run OCR; returns a result containing the recognized text and spatial layout data
    Dim ocrResult As OcrResult = ocrTesseract.Read(imageInput)

    ' Write the output: the original scanned image is preserved with an invisible text layer on top
    ocrResult.SaveAsSearchablePdf("searchablePdf.pdf")
End Using

Imports IronOcr

' Create the OCR engine: defaults to English with balanced speed and accuracy
Dim ocrTesseract As New IronTesseract()

' Required: without this flag the text overlay layer is not built, and SaveAsSearchablePdf produces a plain image PDF
ocrTesseract.Configuration.RenderSearchablePdf = True

' Wrap the TIFF in OcrImageInput: handles DPI detection and page layout automatically
Using imageInput As New OcrImageInput("Potter.tiff")
    ' Run OCR; returns a result containing the recognized text and spatial layout data
    Dim ocrResult As OcrResult = ocrTesseract.Read(imageInput)

    ' Write the output: the original scanned image is preserved with an invisible text layer on top
    ocrResult.SaveAsSearchablePdf("searchablePdf.pdf")
End Using

Imports IronOcr

' Create the OCR engine. RenderSearchablePdf is false by default; no need to set it when using OcrPdfInput directly
Dim ocrTesseract As New IronTesseract()

' Load pages 1–10 (indices 0–9) only; PageIndices avoids loading and OCR-ing the full document unnecessarily
Using pdfInput As New OcrPdfInput("multi-page-scan.pdf", PageIndices:=Enumerable.Range(0, 10))
    ' Run OCR across all selected pages in order
    Dim result As OcrResult = ocrTesseract.Read(pdfInput)

    ' Write the searchable PDF; true = apply the input's image filters to the embedded page images in the output
    result.SaveAsSearchablePdf("searchable-multi-page.pdf", True)
End Using

Imports IronOcr

' Create the OCR engine. RenderSearchablePdf is false by default; no need to set it when using OcrPdfInput directly
Dim ocrTesseract As New IronTesseract()

' Load pages 1–10 (indices 0–9) only; PageIndices avoids loading and OCR-ing the full document unnecessarily
Using pdfInput As New OcrPdfInput("multi-page-scan.pdf", PageIndices:=Enumerable.Range(0, 10))
    ' Run OCR across all selected pages in order
    Dim result As OcrResult = ocrTesseract.Read(pdfInput)

    ' Write the searchable PDF; true = apply the input's image filters to the embedded page images in the output
    result.SaveAsSearchablePdf("searchable-multi-page.pdf", True)
End Using

Imports IronOcr

' Create OCR engine: filters are applied at the OcrInput level, so no configuration changes are needed here
Dim ocr As New IronTesseract()
Dim ocrInput As New OcrInput()

' Load the scanned PDF as the OCR source
ocrInput.LoadPdf("invoice.pdf")

' Convert to grayscale: removes color noise that can reduce OCR accuracy on color-printed documents
ocrInput.ToGrayScale()
' Run OCR on the preprocessed input
Dim result As OcrResult = ocr.Read(ocrInput)

' Write the searchable PDF; True = embed the grayscale-filtered image rather than the original color scan
result.SaveAsSearchablePdf("outputGrayscale.pdf", True)

Imports IronOcr

' Create OCR engine: filters are applied at the OcrInput level, so no configuration changes are needed here
Dim ocr As New IronTesseract()
Dim ocrInput As New OcrInput()

' Load the scanned PDF as the OCR source
ocrInput.LoadPdf("invoice.pdf")

' Convert to grayscale: removes color noise that can reduce OCR accuracy on color-printed documents
ocrInput.ToGrayScale()
' Run OCR on the preprocessed input
Dim result As OcrResult = ocr.Read(ocrInput)

' Write the searchable PDF; True = embed the grayscale-filtered image rather than the original color scan
result.SaveAsSearchablePdf("outputGrayscale.pdf", True)

result.SaveAsSearchablePdf("output.pdf", False, "Fonts/LiberationSerif-Regular.ttf")

result.SaveAsSearchablePdf("output.pdf", False, "Fonts/LiberationSerif-Regular.ttf")

result.SaveAsSearchablePdf("output.pdf", False, "Fonts/LiberationSerif-Regular.ttf", "MyFont")

result.SaveAsSearchablePdf("output.pdf", False, "Fonts/LiberationSerif-Regular.ttf", "MyFont")

' Return as a byte array: suited for storing in a database or sending in an HTTP response body
Dim pdfByte As Byte() = ocrResult.SaveAsSearchablePdfBytes()

' Return as a stream: suited for uploading to cloud storage or piping to another I/O operation without buffering the full file
Dim pdfStream As Stream = ocrResult.SaveAsSearchablePdfStream()

' Return as a byte array: suited for storing in a database or sending in an HTTP response body
Dim pdfByte As Byte() = ocrResult.SaveAsSearchablePdfBytes()

' Return as a stream: suited for uploading to cloud storage or piping to another I/O operation without buffering the full file
Dim pdfStream As Stream = ocrResult.SaveAsSearchablePdfStream()

Imports IronOcr
Imports System.IO

Public Class SearchablePdfExporter
    Public Async Function ProcessAndUploadPdf(inputPath As String) As Task
        Dim ocr As New IronTesseract With {
            .Configuration = { .RenderSearchablePdf = True }
        }

        ' Process the input
        Using input As New OcrImageInput(inputPath)
            Dim result = ocr.Read(input)

            ' Option 1: Save to database as byte array
            Dim pdfBytes As Byte() = result.SaveAsSearchablePdfBytes()
            ' Store pdfBytes in database BLOB field

            ' Option 2: Upload to cloud storage using stream
            Using pdfStream As Stream = result.SaveAsSearchablePdfStream()
                ' Upload stream to Azure Blob Storage, AWS S3, etc.
                Await UploadToCloudStorage(pdfStream, "searchable-output.pdf")
            End Using

            ' Option 3: Return as web response
            ' Return File(pdfBytes, "application/pdf", "searchable.pdf")
        End Using
    End Function

    Private Async Function UploadToCloudStorage(stream As Stream, fileName As String) As Task
        ' Cloud upload implementation
    End Function
End Class

Imports IronOcr
Imports System.IO

Public Class SearchablePdfExporter
    Public Async Function ProcessAndUploadPdf(inputPath As String) As Task
        Dim ocr As New IronTesseract With {
            .Configuration = { .RenderSearchablePdf = True }
        }

        ' Process the input
        Using input As New OcrImageInput(inputPath)
            Dim result = ocr.Read(input)

            ' Option 1: Save to database as byte array
            Dim pdfBytes As Byte() = result.SaveAsSearchablePdfBytes()
            ' Store pdfBytes in database BLOB field

            ' Option 2: Upload to cloud storage using stream
            Using pdfStream As Stream = result.SaveAsSearchablePdfStream()
                ' Upload stream to Azure Blob Storage, AWS S3, etc.
                Await UploadToCloudStorage(pdfStream, "searchable-output.pdf")
            End Using

            ' Option 3: Return as web response
            ' Return File(pdfBytes, "application/pdf", "searchable.pdf")
        End Using
    End Function

    Private Async Function UploadToCloudStorage(stream As Stream, fileName As String) As Task
        ' Cloud upload implementation
    End Function
End Class

Imports IronOcr

Dim advancedOcr As New IronTesseract With {
    .Configuration = New TesseractConfiguration With {
        .RenderSearchablePdf = True,
        .TesseractVariables = New Dictionary(Of String, Object) From {
            {"preserve_interword_spaces", 1},
            {"tessedit_char_whitelist", "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"}
        },
        .PageSegmentationMode = TesseractPageSegmentationMode.SingleColumn
    },
    .Language = OcrLanguage.EnglishBest
}

Imports IronOcr

Dim advancedOcr As New IronTesseract With {
    .Configuration = New TesseractConfiguration With {
        .RenderSearchablePdf = True,
        .TesseractVariables = New Dictionary(Of String, Object) From {
            {"preserve_interword_spaces", 1},
            {"tessedit_char_whitelist", "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"}
        },
        .PageSegmentationMode = TesseractPageSegmentationMode.SingleColumn
    },
    .Language = OcrLanguage.EnglishBest
}