LBitmap::AddShadow

#include "ltwrappr.h"

virtual L_INT LBitmap::AddShadow (uAngle, uThreshold, uFlags)

Adds shadows to the bitmap.

Parameters

L_UINT uAngle

Angle value indicating the direction of the light source producing the shadow. Possible values are:

Value Meaning
SHADOW_E [0] East
SHADOW_NE [1] Northeast
SHADOW_N [2] North
SHADOW_NW [3] Northwest
SHADOW_W [4] West
SHADOW_SW [5] Southwest
SHADOW_S [6] South
SHADOW_SE [7] Southeast

L_UINT uThreshold

Threshold value used to determine which pixels will be affected. Valid values range are:

When uFlags = COLOR_RGB, any component (R, G, or B) of a pixel with a value less than the uThreshold value is not affected. When uFlags = COLOR_GRAY, any pixel where the master channel value* is less than the uThreshold value is not affected.

L_UINT uFlags

Type of the shadow. Possible values are:

Value Meaning
SHADOW_CLR_RGB [0] Shadows are colored.
SHADOW_CLR_GRAY [1] Shadows are grayscale.

Returns

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

Comments

This function applies a convolution matrix upon each color component and then combines the results in order to add shadows.

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 signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

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 LBase::EnableStatusCallback.

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.

See Also

Functions

Topics

Example

L_INT LBitmap__AddShadowExample(LBitmap *pLeadBitmap)  
{ 
    
   /* Apply  shadow effect  to the image*/ 
   return pLeadBitmap->AddShadow (SHADOW_SE, 0, SHADOW_CLR_GRAY);  
} 
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