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L_BlankPageDetectorBitmap

Summary

Determines whether the scanned image is a blank page.

Syntax

#include "l_bitmap.h"

L_LTIMGCOR_API L_INT EXT_FUNCTION L_BlankPageDetectorBitmap(pBitmap, pOptions, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the image to be tested.

pBLANKPAGEDETECTOROPTIONS pOptions

Pointer to a BLANKPAGEDETECTOROPTIONS structure containing options for detecting whether an image is a blank page.

L_UINT uFlags

Flags that indicate how to consider blank pages and the function behavior. You can combine values when appropriate by using a bitwise OR ( | ). Possible values are:

Consider noisy page as a blank page:

Value	Meaning
BLANK_DETECT_EMPTY	[0x00000000] A page must be totally blank.
BLANK_DETECT_NOISY	[0x00000001] A page may have some noise. This is the default value.

Consider page which bleeds through its other side as a blank page:

Value	Meaning
BLANK_NOT_BLEED_THROUGH	[0x00000000] Do not ignore bleed through from the page.
BLANK_BLEED_THROUGH	[0x00000010] Ignore bleed through from the page. This is the default value.

Consider lined page as a blank page:

Value	Meaning
BLANK_DONT_DETECT_LINES	[0x00000000] Do not consider lined page as a blank page. This is the default value.
BLANK_DETECT_LINES	[0x00000100] Consider lined page as a blank page.

Indicate whether to ignore blank spaces around the page edges:

Value	Meaning
BLANK_DONT_USE_ACTIVE_AREA	[0x00000000] Do not ignore blank spaces around the page edges. This is the default value.
BLANK_USE_ACTIVE_AREA	[0x00001000] Ignore blank spaces around the page edges.

Indicate whether to use default margins or user-specified margins:

Value	Meaning
BLANK_DEFAULT_MARGIN	[0x00000000] Use default margins, which are computed automatically by the function based on the page dimensions. This is the default value.
BLANK_USER_MARGIN	[0x00010000] Use the user-specified margins, which are specified in PMargins.

Returns

Value	Meaning
SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

Scanned images can contain blank (empty) pages. This function determines whether the scanned image is a blank page or not, detects noisy, bleed through, and lined blank pages with high precision and speed, and provides a percentage accuracy of the result. This function helps reduce the disk storage space required for scanned images.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Blank Page Function - Before

Blank Page Function - After

View additional platform support for this Blank Page function.

Required DLLs and Libraries

LTIMGCOR
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64, Linux.

Example

L_INT BlankPageDetectorBitmapExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle hold the loaded image. */ 
 
   /* Load the bitmap, keeping the bits per pixel of the file */ 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH("IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   /* Check if the image is a blank page */ 
   BLANKPAGEDETECTOROPTIONS Options = { 0 }; 
   Options.uStructSize = sizeof(BLANKPAGEDETECTOROPTIONS); 
   Options.bIsBlank = 1; 
   Options.uAccuracy = 0; 
 
   nRet = L_BlankPageDetectorBitmap(&LeadBitmap, &Options, BLANK_DETECT_NOISY | BLANK_BLEED_THROUGH | BLANK_DEFAULT_MARGIN); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   if (Options.bIsBlank) 
      OutputDebugString(L_TEXT("Image is blank.\n")); 
   else 
      OutputDebugString(L_TEXT("Image is not blank.\n")); 
 
   //free bitmap 
   L_FreeBitmap(&LeadBitmap); 
 
   return nRet; 
}