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LBitmap::IntensityDetect

Summary

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). 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::IntensityDetect(uLow, uHigh, crInColor, crOutColor, uChannel, uFlags = 0)

Parameters

L_UINT uLow

Lowest intensity to detect. Possible values ranges are:

0 to 65535 for 64-bit, 48-bit and 16-bit grayscale images.
0 to 4095 for 12-bit grayscale images.
0 to 255 otherwise.

L_UINT uHigh

Highest intensity to detect. Possible values ranges are:

0 to 65535 for 64-bit, 48-bit and 16-bit grayscale images.
0 to 4095 for 12-bit grayscale images.
0 to 255 otherwise.

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

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

The function can process two or more channels at a time by OR-ing two or more flags.

The function can obtain the same result as that of the LBitmap::IntensityDetect (uLow, uHigh) function (version 13 and before) by passing the following parameters:

LBitmap::IntensityDetect(uLow, uHigh, RGB(0, 0, 0), RGB(255, 255, 255), CHANNEL_RED | CHANNEL_GREEN | CHANNEL_BLUE);

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

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.

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))

Intensity Detect Function - Before

Intensity Detect Function - After

View additional platform support for this Intensity Detect 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__IntensityDetectExample() 
{ 
   L_INT nRet; 
   LBitmap LeadBitmap; 
    
   nRet =LeadBitmap.Load(MAKE_IMAGE_PATH(TEXT("dirty_barcode.jpg")), 0,ORDER_BGR); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet =LeadBitmap.IntensityDetect(128, 255, RGB(0, 0, 0), RGB(255, 255, 255), IDB_CHANNEL_MASTER); 
   if(nRet !=SUCCESS) 
      return nRet; 
   return SUCCESS; 
}