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LBitmap::HistoEqualize

Summary

Linearizes the number of pixels in the class object's bitmap, based on the specified color space. This can be used to bring out the detail in dark areas of an image. This function is also useful for pre-processing images for the purpose of improving barcode recognition results.

Syntax

#include "ltwrappr.h"

virtual L_INT LBitmap::HistoEqualize(uFlags = 0)

Parameters

L_UINT32 uFlags

Flag that indicates which color space to equalize. Possible values are:

Value	Meaning
RGB_SPACE	[0x0001] Linearizes the number of pixels across the RGB color space.(separated channels)
YUV_SPACE	[0x0002] Linearizes the number of pixels across the YUV color space.(Best results)
GRAY_SPACE	[0x0004] Linearizes the number of pixels per gray level in a gray level representation of the image.

Returns

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

Comments

Previously this function only equalized the number of pixels per gray level, using a gray level representation of the image. This functionality is now obtained by passing GRAY_SPACE for uFlags.

For the best results, set uFlags to YUV_SPACE.

To update a status bar or detect a user interrupt during execution of this function, refer to LBase::EnableStatusCallback.

This function can process the whole image or a region of the image.

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits.

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.

Histogram Equalize Function - Before

Histogram Equalize Function - After

View additional platform support for this Histogram Equalize function.

Required DLLs and Libraries

LTDIS
LTFIL
LTIMGCLR
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.

Example

L_INT LBitmap__HistoEqualizeExample() 
{ 
   L_INT nRet; 
   LBitmap LeadBitmap; 
    
   nRet =LeadBitmap.Load(MAKE_IMAGE_PATH(TEXT("image1.cmp")), 0,ORDER_BGR); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet =LeadBitmap.HistoEqualize(0); 
   if(nRet !=SUCCESS) 
      return nRet; 
 
   return SUCCESS; 
}