Changes the color of each pixel in a bitmap to the median color of pixels in its neighborhood. This is similar to the L_AverageFilterBitmap function, but it is used for noise reduction, rather than a blur effect.
#include "l_bitmap.h"
L_LTIMGCOR_API L_INT L_MedianFilterBitmap(pBitmap, uDim, uFlags)
Pointer to the bitmap handle referencing the bitmap to be converted.
Dimensions of the neighborhood used for filtering (uDim x uDim), in pixels.
Reserved for future use. Must be 0.
Value | Meaning |
---|---|
SUCCESS | The function was successful. |
< 1 | An error occurred. Refer to Return Codes. |
You control the effect by specifying the size of the neighborhood that is used for calculating the median value. For 8x8, pass 8 in the uDim
parameter.
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.
If the bitmap has a region, this function works only on the region. If the bitmap does not have a region, this function works on the entire bitmap.
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.
Median Function - Before
Median Function - After
View additional platform support for this Median function.
Win32, x64, Linux.
For complete sample code, refer to the CHILD.C module of the DEMO example.
This example loads a bitmap and applies an median filter.
L_INT MedianFilterBitmapExample(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("NaturalFruits.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
if (nRet != SUCCESS)
return nRet;
/* Apply a median filter with a neighborhood of 3x3 pixels */
nRet = L_MedianFilterBitmap(&LeadBitmap, 3, 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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