L_DirectionEdgeStatisticalBitmap

#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_DirectionEdgeStatisticalBitmap(pBitmap, uDim, nThreshold, nAngle, crEdgeColor, crBkColor, uFlags)

Detects the variation of colors in the specified direction using statistical indices. It is similar to L_EdgeDetectStatisticalBitmap, but this function allows you to specify the direction angle.

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the bitmap to which the edge detector is applied.

L_UINT uDim

The dimension or the number of pixels used to calculate the edge in the specified direction.

L_INT nThreshold

Threshold value used to determine which pixels are edge pixels. If the difference in the intensity value between the pixel being tested and the average intensity of the pixels in the uDim around it is greater than this value, the pixel is an edge pixel. The threshold range for the 16, 48, and 64-bit bitmaps is from 0 to 65535 and for 12-bit bitmaps from 0 to 4095. Otherwise, it is from 0 to 255. The threshold is applied on channels separately.

L_INT nAngle

Angular amount that specifies edge detector direction, in hundredths of degrees. Valid values range from 18000 through 18000. Positive valued angles are produced by counterclockwise rotation above the horizon and negative valued angles are produced by clockwise rotation below the horizon. This value is divided internally by 100.

COLORREF crEdgeColor

The COLORREF value that specifies the edge color. You can specify a COLORREF value, such as the return value of the Windows RGB macro, or you can use the PALETTEINDEX macro to specify a palette color.

COLORREF crBkColor

The COLORREF value that specifies the non edge color. You can specify a COLORREF value, such as the return value of the Windows RGB macro, or you can use the PALETTEINDEX macro to specify a palette color.

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 edges are detected by applying a statistical filter that analyzes the variations of colors in a specified direction around each pixel.

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

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.

The threshold range for 16, 48 and 64-bit images is from 0 to 65535 for unsigned images, and from –32768 to +32767 for signed images. For 12-bit images, the threshold range is from 0 to 4095 for unsigned images, and from –2048 to +2047 for signed images. Otherwise, it is from 0 to 255. The threshold is applied to channels separately.

Required DLLs and Libraries

Platforms

Win32, x64, Linux.

See Also

Functions

Topics

Example

This example loads a bitmap and find its edges using a 45 degree angle, a 128 threshold, and a size equal to 15

L_INT DirectionEdgeStatisticalBitmapExample(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("ImageProcessingDemo\\NaturalFruits.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
 
   /* Find the edges in the bitmap*/ 
   nRet = L_DirectionEdgeStatisticalBitmap (&LeadBitmap, 15, 128, 4500, RGB(255, 255, 255), RGB(0, 0, 0), 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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