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L_GetBitmapStatisticsInfo

Summary

Returns statistical information about the bitmap.

Syntax

#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_GetBitmapStatisticsInfo (pBitmap, pStatisticsInfo, uChannel, nStart, nEnd, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the bitmap on which to apply the effect.

pSTATISTICSINFO pStatisticsInfo

Address of the STATISTICSINFO structure variable to be updated with the image information.

L_UINT uChannel

Flag that indicates the channel for which to get the information. This value is ignored if the bitmap is 12 or 16-bit grayscale. Possible values are:

Value	Meaning
CHANNEL_MASTER *	[0] All channels.
CHANNEL_RED	[1] Red channel only.
CHANNEL_GREEN	[2] Green channel only.
CHANNEL_BLUE	[3] Blue channel only.

L_INT nStart

Indicates the beginning color value of the range for the evaluation.

L_INT nEnd

Indicates the ending color value of the range for the evaluation.

Returns

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

Comments

This function calculates statistical information about the bitmap.

The nStart and nEnd parameters designate the range of colors that will be taken in consideration for producing the results. Only the values between nStart and nEnd are used for the calculation of the results. The range of each one depends on the bits per pixel of the bitmap: in the case of 8 bits per component (RGB), the range is between 0 and 255; for 16 bits, the range is 0 through 65535 for unsigned images and from -32768 to 32767 for signed images; and for 12 bits, the range is 0 through 4095.

This function supports signed data images. 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 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.

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

LTIMGEFX
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 GetBitmapStatisticsInfoExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle for the image */ 
   STATISTICSINFO  StatisticsInfo; 
 
   /* Load a bitmap at 24 bits per pixel  */ 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("Master.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   /*Get statistical image information */ 
   nRet = L_GetBitmapStatisticsInfo(&LeadBitmap, &StatisticsInfo, CHANNEL_MASTER, 0, 255, 0); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   //free Bitmap 
   if (LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   return SUCCESS; 
}