Foxit Classic OCR (C++)

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Classic Foxit C++ OCR — Production-Proven Recognition

The production-proven engine: Foxit’s C++ OCR add-on (foxit::addon::ocr) with line-level confidence reporting, deskew and despeckle built in, and three output modes — searchable, natively editable, or editable via graphics-object post-processing.

Drop PDF or images here, or click to upload

Supports PDF, TIFF, JPG, BMP, PNG — C++ native engine with built-in deskew & despeckle

How it works

The engine. Uploads go through a thin PHP proxy on this server to a FastAPI service on a Windows workstation, which runs a small C++ binary built on Foxit’s classic OCR add-on (foxit::addon::ocr). Unlike most OCR APIs, it reports line-level confidence — toggle the Confidence overlay or the Review tab after a run to see exactly which lines the engine was unsure about.

The knobs. Auto-rotate maps to the binary’s --correct-skew flag: on, the engine detects page orientation and deskews; off, it trusts the input orientation — needed for forms with prominent sideways margin text, which can otherwise trick the engine into 180° page flips. The ⚙ Advanced panel exposes the underlying OCRConfig fields one-for-one: picture detection, noise removal, text-extraction mode, DPI override, and a minimum-confidence threshold.

Three output modes. OCR for Search (is_editable=false) keeps the page image and adds an invisible text overlay — the classic searchable PDF. OCR for Edit (native) (is_editable=true) is the add-on’s own editable output, rebuilt as visible text objects in a single SDK call. OCR for Edit (post-process) takes the searchable PDF and runs a second Foxit SDK pass that walks every page graphics object, inserts a white-fill PathObject underneath each invisible text object, then flips the text mode from e_ModeInvisible to e_ModeFill — the original page image (photos, diagrams, logos) is preserved verbatim while the OCR’d text becomes real, visible, editable text. A neat demonstration of graphics-object manipulation in the SDK, and it takes ~150 ms for a 24-page document.

Sample implementation code

The OCR add-on pipeline this demo runs — initialize the engine, set the language, process, save — in each SDK language binding. Condensed for clarity.

#include "common/fs_common.h"
#include "pdf/fs_pdfdoc.h"
#include "addon/ocr/fs_ocr.h"

using namespace foxit;
using namespace foxit::common;
using namespace foxit::pdf;
using namespace foxit::addon::ocr;

int main() {
  Library::Initialize(sn, key);            // key must include the OCR module
  // Point the engine at the OCR resource directory shipped with the add-on.
  OCREngine::Initialize(L"/path/to/ocr_resources");
  OCREngine::SetLanguages("English");      // comma-separated for multi-language

  PDFDoc doc(L"scan.pdf");
  if (doc.Load() != e_ErrSuccess) return 1;

  // is_editable = false → searchable PDF: page image kept, invisible text layer.
  // is_editable = true  → editable PDF: the engine's native editable output.
  OCRProcessor processor;
  processor.ProcessDocument(doc, /*is_editable=*/false);
  // Per-page alternative: processor.ProcessPage(page, is_editable)
  // — the engine reports line-level confidence you can read back per line.

  doc.SaveAs(L"searchable.pdf",
             PDFDoc::e_SaveFlagNoOriginal | PDFDoc::e_SaveFlagXRefStream);
  OCREngine::Release();
  Library::Release();
  return 0;
}

using foxit;
using foxit.common;
using foxit.pdf;
using foxit.addon.ocr;

Library.Initialize(sn, key);             // key must include the OCR module
// Point the engine at the OCR resource directory shipped with the add-on.
OCREngine.Initialize(@"C:\foxit\ocr_resources");
OCREngine.SetLanguages("English");       // comma-separated for multi-language

using var doc = new PDFDoc("scan.pdf");
doc.Load(null);

// isEditable = false → searchable PDF: page image kept, invisible text layer.
// isEditable = true  → editable PDF: the engine's native editable output.
var processor = new OCRProcessor();
processor.ProcessDocument(doc, false);
// Per-page alternative: processor.ProcessPage(page, isEditable)
// — the engine reports line-level confidence you can read back per line.

doc.SaveAs("searchable.pdf",
    (int)(PDFDoc.SaveFlags.e_SaveFlagNoOriginal
        | PDFDoc.SaveFlags.e_SaveFlagXRefStream));
OCREngine.Release();
Library.Release();

import com.foxit.sdk.common.Library;
import com.foxit.sdk.pdf.PDFDoc;
import com.foxit.sdk.addon.ocr.*;

Library.initialize(sn, key);             // key must include the OCR module
// Point the engine at the OCR resource directory shipped with the add-on.
OCREngine.initialize("/opt/foxit/ocr_resources");
OCREngine.setLanguages("English");       // comma-separated for multi-language

PDFDoc doc = new PDFDoc("scan.pdf");
doc.load(null);

// isEditable = false → searchable PDF: page image kept, invisible text layer.
// isEditable = true  → editable PDF: the engine's native editable output.
OCRProcessor processor = new OCRProcessor();
processor.processDocument(doc, false);
// Per-page alternative: processor.processPage(page, isEditable)
// — the engine reports line-level confidence you can read back per line.

doc.saveAs("searchable.pdf",
    PDFDoc.e_SaveFlagNoOriginal | PDFDoc.e_SaveFlagXRefStream);
OCREngine.release();
Library.release();

from FoxitPDFSDKPython3 import *

Library.Initialize(sn, key)              # key must include the OCR module
# Point the engine at the OCR resource directory shipped with the add-on.
OCREngine.Initialize("/opt/foxit/ocr_resources")
OCREngine.SetLanguages("English")        # comma-separated for multi-language

doc = PDFDoc("scan.pdf")
assert doc.Load("") == e_ErrSuccess

# is_editable = False → searchable PDF: page image kept, invisible text layer.
# is_editable = True  → editable PDF: the engine's native editable output.
processor = OCRProcessor()
processor.ProcessDocument(doc, False)
# Per-page alternative: processor.ProcessPage(page, is_editable)
# — the engine reports line-level confidence you can read back per line.

doc.SaveAs("searchable.pdf",
           PDFDoc.e_SaveFlagNoOriginal | PDFDoc.e_SaveFlagXRefStream)
OCREngine.Release()
Library.Release()

// Foxit PDF SDK for Node.js (naming follows the Node binding conventions)
const {
  Library, PDFDoc, OCREngine, OCRProcessor,
} = require('@foxitsoftware/foxit-pdf-sdk-node');

Library.initialize(sn, key);             // key must include the OCR module
// Point the engine at the OCR resource directory shipped with the add-on.
OCREngine.initialize('/opt/foxit/ocr_resources');
OCREngine.setLanguages('English');       // comma-separated for multi-language

const doc = new PDFDoc('scan.pdf');
doc.load(null);

// isEditable = false → searchable PDF: page image kept, invisible text layer.
// isEditable = true  → editable PDF: the engine's native editable output.
const processor = new OCRProcessor();
processor.processDocument(doc, false);
// Per-page alternative: processor.processPage(page, isEditable)
// — the engine reports line-level confidence you can read back per line.

doc.saveAs('searchable.pdf',
    PDFDoc.e_SaveFlagNoOriginal | PDFDoc.e_SaveFlagXRefStream);
OCREngine.release();
Library.release();

Samples are condensed for clarity — production code should check every return value and wrap SDK calls in the binding’s exception handling. Exact class/method names can differ slightly between SDK releases; the pipeline shown mirrors the real source behind this demo (foxit_cpp_classic.cpp, a heavily-commented customer sample), which adds the OCRConfig options and --correct-skew handling exposed in the toolbar above. The “Edit (post-process)” mode is a separate ~100-line SDK pass over the page graphics objects — see the explainer.

`←` `→`	Previous / Next page
`Ctrl`+`Shift`+`Enter`	OCR all pages
`+` `−`	Zoom in / out
`0`	Fit to width
`R`	Rotate right
`Shift`+`R`	Rotate left
`Del`	Delete current page
`?`	Show this dialog
`Esc`	Close dialog

Foxit Classic OCR C++ Native

Classic Foxit C++ OCR — Production-Proven Recognition

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How it works

Sample implementation code