#include "l_bitmap.h"
L_LTIMGCOR_API L_INT EXT_FUNCTION L_AutoBinarizeBitmap(pBitmap, uFactor, uFlags)
pBITMAPHANDLE pBitmap; |
/* pointer to the bitmap handle */ |
L_UINT uFactor; |
/* threshold factor */ |
L_UINT uFlags; |
/* flags */ |
Applies binary segmentation to a bitmap automatically.
This feature is available in version 16 or higher.
Parameter |
Description |
|
pBitmap |
Pointer to the bitmap handle referencing the bitmap having binary segmentation applied automatically. |
|
uFactor |
Threshold Factor. The meaning of this factor depends on which type of thresholding is being used. For more information see the description of the uFlags parameter. |
|
uFlags |
Flags that indicate the type of pre-processing to perform on the bitmap and the type of thresholding to use. You can use a bitwise OR (|) to specify one flag from each group. |
|
|
The following flags indicate the type of pre-processing to perform on the bitmap: |
|
|
Value |
Meaning |
|
AUTO_BINARIZE_PRE_AUTO |
[0x00000000] Perform automatic pre-processing. This is the default value. |
|
AUTO_BINARIZE_NO_PRE |
[0x00000001] Do not perform pre-processing. |
|
AUTO_BINARIZE_PRE_BG_ELIMINATION |
[0x00000002] Eliminate the background of the bitmap but keep the key features, such as text. |
|
AUTO_BINARIZE_PRE_LEVELING |
[0x00000004] Perform automatic color leveling. |
|
The following flags indicate type of threshold to use: |
|
|
Value |
Meaning |
|
AUTO_BINARIZE_THRESHOLD_AUTO |
[0x00000000] Perform automatic thresholding. This is the default value. |
|
AUTO_BINARIZE_THRESHOLD_USER |
[0x00000010] Let the user choose the threshold value, to be passed in uFactor. Valid values range from 0 to 255. |
|
AUTO_BINARIZE_THRESHOLD_PERCENTILE |
[0x00000020] Perform percentile thresholding. In this case uFactor is the percentage of black pixels at which to perform thresholding, expressed in hundredths of a percent. For example, 500 means 5 percent. Valid values range from 0 to 10000. |
|
AUTO_BINARIZE_THRESHOLD_MEDIAN |
[0x00000040] Perform median thresholding. |
Returns
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
Comments
AutoBinarize converts a colored image into a bitonal image automatically, without losing important image features such as text. This function uses several pre-processing and threshold operations which enable the user to extract the key features of any colored image. It can be adjusted to be suitable for a specific input device, such as a scanner or camera. It is ideal for making unclear document images more readable. This function is especially useful for improving recognition results (OCR, Barcode, OMR, ICR).
L_AutoBinarizeBitmap options:
Automatic pre-processing
Pre-processing using background elimination
Pre-processing using color leveling
Perform automatic, percentile or median threshold
Manually specify a threshold value
To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback.
This function does not support 12 and 16-bit grayscale and 48 and 64-bit color images. If the image is 12 and 16-bit grayscale and 48 and 64-bit color, the function will not return an error.
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.
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.
See Also
Example
#define MAKE_IMAGE_PATH(pFileName) TEXT("C:\\Users\\Public\\Documents\\LEADTOOLS Images\\")pFileName #if defined (LEADTOOLS_V16_OR_LATER) L_INT AutoBinarizeBitmapExample(L_VOID) { L_INT nRet; BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the loaded image. */ /* Load the bitmap, keeping the bits per pixel of the file */ nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("cannon.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); if(nRet !=SUCCESS) return nRet; nRet = L_AutoBinarizeBitmap(&LeadBitmap, 0, AUTO_BINARIZE_PRE_AUTO | AUTO_BINARIZE_THRESHOLD_AUTO); if(nRet !=SUCCESS) return nRet; nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); if(nRet !=SUCCESS) return nRet; //free bitmap if(LeadBitmap.Flags.Allocated) L_FreeBitmap(&LeadBitmap); return SUCCESS; } #endif // LEADTOOLS_V16_OR_LATER