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Sets the overlay bitmap of this L_OcrPage.
#include "ltocr.h"
L_LTOCR_API L_INT EXT_FUNCTION L_OcrPage_SetOverlayBitmap(page, bitmapHandle)
Handle to the OCR page.
BITMAPHANDLE to use to update the page overlay bitmap.
Value | Meaning |
---|---|
SUCCESS | The function was successful. |
< 1 | An error occurred. Refer to Return Codes. |
The overlay image of an L_OcrPage will be used when the image is saved by an L_OcrDocument in the following situations:
By default, the overlay image is the original image used to create the page. It is the same value obtained by calling L_OcrPage_GetBitmap with L_OcrPageBitmapType_Original option.
In some situation, the user might want to use a different bitmap as the overlay. For example, a smaller version is passed to the OCR engine to conserve memory while the original version will only be used on save purposes in a PDF with image/text option. You can call L_OcrPage_SetOverlayBitmap before saving the document (memory-based) or adding the page to the document (file-based) and the engine will use this new bitmap as the overlay value. If auto-preprocessing was performed on the page through L_OcrPage_AutoPreprocess, then the same values might need to be applied to the overlay as well. Use L_OcrPage_GetAutoPreprocessValues to get the accumulative values of any inversion, rotation or deskewing applied by the pre-processor.
To clear the temporarily overlay image, call L_OcrPage_SetOverlayBitmap with a NULL value.
To get the overlay image at any time, call L_OcrPage_GetOverlayBitmap. Note that this property will return the same image reference passed to the last L_OcrPage_SetOverlayBitmap call. It will not return the original image.
The overlay bitmap is not freed by this L_OcrPage.
L_INT L_OcrPage_SetOverlayBitmapExample()
{
BITMAPHANDLE bitmap = { 0 };
L_OcrEngine ocrEngine = NULL;
L_OcrPage ocrPage = NULL;
L_OcrDocumentManager ocrDocumentManager = NULL;
L_OcrDocument ocrDocument = NULL;
// Create an instance of the engine
L_INT retCode = L_OcrEngineManager_CreateEngine(L_OcrEngineType_LEAD, &ocrEngine);
if(retCode == SUCCESS)
{
// Start the engine using default parameters
retCode = L_OcrEngine_Startup(ocrEngine, NULL, OCR_LEAD_RUNTIME_DIR);
if(retCode != SUCCESS)
return retCode;
// Load a page to be recognized
retCode = L_LoadBitmap(MAKE_IMAGE_PATH(L_TEXT("Ocr1.tif")), &bitmap, sizeof(BITMAPHANDLE), 0, ORDER_RGB, NULL, NULL);
if(retCode != SUCCESS)
goto CLEANUP;
// Add an image to OCR page. don't transfer ownership of the bitmap to the page we will control this original image
retCode = L_OcrPage_FromBitmap(ocrEngine, &ocrPage, &bitmap, L_OcrBitmapSharingMode_None, NULL, NULL);
if(retCode != SUCCESS)
goto CLEANUP;
// Get OCR page default overlay bitmap and save it to disk
BITMAPHANDLE origOverlayBitmap = {0};
retCode = L_OcrPage_GetOverlayBitmap(ocrPage, &origOverlayBitmap, sizeof(BITMAPHANDLE));
if(retCode != SUCCESS)
goto CLEANUP;
// if the OCR page has overlay bitmap they save it before we change it
if(origOverlayBitmap.Flags.Allocated)
L_SaveBitmap(TEXT("OcrPageOrigOverlayBitmap.tif"), &origOverlayBitmap, FILE_CCITT_GROUP4, origOverlayBitmap.BitsPerPixel, 2, NULL);
// Apply some auto preprocessing on the image
L_OcrPage_AutoPreprocess(ocrPage, L_OcrAutoPreprocessPageCommands_All, NULL, NULL);
// resize down our original bitmap into half and set it as the OCR page overlay bitmap to conserve memory.
retCode = L_SizeBitmap(&bitmap, bitmap.Width / 2, bitmap.Height / 2, SIZE_RESAMPLE);
if(retCode != SUCCESS)
goto CLEANUP;
// Now you might want to apply the same auto preprocessing commands applied to the OCR page into the overlay bitmap
// before you set it, to do so, you need to call L_OcrPage_GetAutoPreprocessValues function first to determine what
// kind of preprocessing values were applied to the OCR page
L_OcrPageAutoPreprocessValues autoPreprocessValues = {0};
retCode = L_OcrPage_GetAutoPreprocessValues(ocrPage, &autoPreprocessValues);
if(retCode == SUCCESS)
{
if(autoPreprocessValues.IsInverted)
L_InvertBitmap(&bitmap, 0);
if(autoPreprocessValues.DeskewAngle > 0)
L_DeskewBitmap(&bitmap, NULL,RGB(0, 0, 0), DSKW_PROCESS | DSKW_RESAMPLE);
if(autoPreprocessValues.RotationAngle > 0)
L_RotateBitmap(&bitmap, autoPreprocessValues.RotationAngle, ROTATE_RESAMPLE, RGB(0, 0, 0));
}
// Now save our updated overlay bitmap to disk
L_SaveBitmap(TEXT("OcrPageUpdatedOverlayBitmap.tif"), &bitmap, FILE_CCITT_GROUP4, bitmap.BitsPerPixel, 2, NULL);
retCode = L_OcrPage_SetOverlayBitmap(ocrPage, &bitmap);
if(retCode != SUCCESS)
goto CLEANUP;
// Recognize the page
// Note: Recognize can be called without calling AutoZone or manually adding zones.
// The engine will check and automatically auto-zones the page.
retCode = L_OcrPage_Recognize(ocrPage, NULL, NULL);
if(retCode != SUCCESS)
goto CLEANUP;
//Get the document manager
retCode = L_OcrEngine_GetDocumentManager(ocrEngine, &ocrDocumentManager);
if(retCode != SUCCESS)
goto CLEANUP;
// Create file-based OCR document
retCode = L_OcrDocumentManager_CreateDocument(ocrDocumentManager, &ocrDocument, L_OcrCreateDocumentOptions_AutoDeleteFile, NULL);
if(retCode != SUCCESS)
goto CLEANUP;
// Add page to the document.
retCode = L_OcrDocument_AddPage(ocrDocument, ocrPage);
if(retCode != SUCCESS)
goto CLEANUP;
// Adding the page to a file based document will take a snap shot of the recognition data and store it in the document. At this
// point, the page is no longer needed. So destroy it to free up memory not used anymore
L_OcrPage_Destroy(ocrPage);
// Set the handle to NULL so we do not free it in our clean-up code
ocrPage = NULL;
// Save the document we have as PDF Image/Text
// Get the format options for PDF
DOCWRTPDFOPTIONS pdfOptions;
pdfOptions.Options.uStructSize = sizeof(DOCWRTPDFOPTIONS);
L_OcrDocumentManager_GetFormatOptions(ocrDocumentManager, DOCUMENTFORMAT_PDF, &pdfOptions.Options);
// Set the PDF ImageOverText option to TRUE
pdfOptions.bImageOverText = L_TRUE;
// Give the engine our updated PDF options
L_OcrDocumentManager_SetFormatOptions(ocrDocumentManager, DOCUMENTFORMAT_PDF, &pdfOptions.Options);
retCode = L_OcrDocument_Save(ocrDocument, MAKE_IMAGE_PATH(L_TEXT("Output.pdf")), DOCUMENTFORMAT_PDF, NULL, NULL);
// Now if you opened the saved PDF file you will see our resized image shown as the PDF image over text
// instead of the original OCR page bitmap.
}
CLEANUP:
if(bitmap.Flags.Allocated)
L_FreeBitmap(&bitmap);
if(ocrPage != NULL)
L_OcrPage_Destroy(ocrPage);
if(ocrDocument != NULL)
L_OcrDocument_Destroy(ocrDocument);
if(ocrEngine != NULL)
L_OcrEngine_Destroy(ocrEngine);
return retCode;
}