L_AddBitmapNoise

#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_AddBitmapNoise(pBitmap, uRange, uChannel, uFlags)

Adds random pixels to a bitmap, letting you specify the percentage of coverage and the color plane.

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to process.

L_UINT uRange

Percentage of coverage, expressed in tenths of a percent. Valid values are 0 to 1000.

L_UINT uChannel

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_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

Use this function in order to add random noise to a bitmap.

Use the L_PerlinBitmap function to use a pseudo-random number generator in order to create a Perlin noise, and then procedurally transform that noise into a texture. Depending on the flags that are set, the texture can be saved as a bitmap by itself, or the texture can be combined with another bitmap. For more information, refer to Using the L_PerlinBitmap function.

Use the L_CloudsBitmap function in order to use Perlin equations to generate pseudo-random noise, and then procedurally transform that noise into a cloud-like texture. The L_CloudsBitmap function applies equations to the Perlin noise that are different than those used by the L_PerlinBitmap function.

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 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.

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

For complete sample code, refer to the CHILD.C module of the DEMO example. This example loads a bitmap and adds red noise to it.

L_INT AddBitmapNoiseExample(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("sample2.cmp")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
 
   /* Add red noise with 25 percent coverage */ 
   nRet = L_AddBitmapNoise(&LeadBitmap, 250, CHANNEL_RED, 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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