L_IntensityDetectBitmap

#include "l_bitmap.h"

L_LTIMGCLR_API L_INT L_IntensityDetectBitmap(pBitmap, uLow, uHigh, crInColor, crOutColor, uChannel, uFlags)

Applies binary segmentation to a bitmap by filtering the specified bitmap to detect colors in a specified intensity range, in the specified color channel(s).

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap.

L_UINT uLow

Lowest intensity to detect. Possible values range from 0 - 65535 for 64-bit, 48-bit and 16-bit grayscale images and from 0 - 4095 for 12-bit grayscale images. Otherwise, it is from 0 to 255.

L_UINT uHigh

Highest intensity to detect. Possible values range from 0 - 65535 for 64-bit, 48-bit and 16-bit grayscale images and from 0 - 4095 for 12-bit grayscale images. Otherwise, it is from 0 to 255.

COLORREF crInColor

The color used to fill those pixels having an intensity value between uLow and uHigh. This parameter has no effect if the uChannel parameter is set to IDB_CHANNEL_MASTER. If for example the uChannel parameter is set to IDB_CHANNEL_RED, then the red component of crInColor will be used to fill the pixels having a red component value between uLow and uHigh.

COLORREF crOutColor

The color used to fill those pixels having an intensity value less than uLow or greater than uHigh. This parameter has no effect if the uChannel parameter is IDB_CHANNEL_MASTER. If for example the uChannel parameter is set to IDB_CHANNEL_RED, then the red component of crOutColor will be used to fill the pixels having a red component value less than uLow or greater than uHigh.

L_UINT uChannel

A value that indicates the channel to process. Possible values are:

Value Meaning
IDB_CHANNEL_MASTER * [0x0000] Grayscale Channel.
IDB_CHANNEL_RED [0x0001] Red Channel.
IDB_CHANNEL_GREEN [0x0010] Green Channel.
IDB_CHANNEL_BLUE [0x0100] Blue Channel.

L_UINT32 uFlags

Reserved for future use. Must be 0.

Returns

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

Comments

This function is useful for pre-processing images to improve barcode recognition results.

The image is divided into two parts: inner and outer, corresponding to the values of uLow and uHigh.

Process 2 or more channels at a time by OR-ing two or more flags.

To obtain the same result as the old L_IntensityDetectBitmap(pBitmap, uLow, uHigh) of version 13 and earlier, pass the following parameters:

L_IntensityDetectBitmap(pBitmap, uLow, uHigh, RGB(0, 0, 0), RGB(255, 255, 255), CHANNEL_RED | CHANNEL_GREEN | CHANNEL_BLUE); 

This function also 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 in the Document and Medical Imaging 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.

To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback

Calculating Master Channel Values

In order to speed up widely used image processing filters in LEADTOOLS, the grayscale value (master channel) of a colored image is calculated using the following formulas:

#define CalcGrayValue(r, g, b) ((L_UCHAR)(((L_UCHAR) (((2 * (L_UINT) (r)) + (5 * (L_UINT) (g)) + (L_UINT) (b) + 4) / 8)))) 
#define CalcGrayValue16(r, g, b) ((L_UINT16) (((2 * (L_UINT32) (r)) + (5 * (L_UINT32) (g)) + (L_UINT32) (b) + 4) / 8)) 
#define CalcGrayValue32(r, g, b) ((L_UINT32) (((2 * (L_UINT32) (r)) + (5 * (L_UINT32) (g)) + (L_UINT32) (b) + 4) / 8)) 

Required DLLs and Libraries

Platforms

Win32, x64, Linux.

See Also

Functions

Topics

Example

This example loads a bitmap and applies the filter on it.

L_INT IntensityDetectBitmapExample(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("dirty_barcode.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
 
   /* Apply the filter*/ 
   nRet = L_IntensityDetectBitmap(&LeadBitmap, 128, 255, RGB(0, 0, 0), RGB(255, 255, 255), IDB_CHANNEL_MASTER, 0); 
   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; 
} 

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