Adjusts the image contrast using the Contrast Limited Adaptive Histogram Equalizer (CLAHE) method, which uses several histograms each corresponding to a distinct section in the image while limiting the amplification of the noise in the image.
#include "l_bitmap.h"
L_LTIMGCOR_API L_INT L_CLAHE(pBitmap0, Alpha, TileSize, nfclipLimit, nBinNumber, uFlags)
Pointer to the bitmap handle that references the bitmap to be affected.
Non-negative real scalar specifying a distribution parameter.
Positive integer specifying the size of tiles ranging from 1 to 60.
Real scalar in the range [0, 1] that specifies a contrast enhancement limit. Higher numbers result in more contrast.
Multiple of 2 integer in the range [2, 1024] that specifies the number of bins for the histogram used in building a contrast enhancing transformation.
Flags specifying the desired histogram shape for the image tiles. Possible values are:
Value | Meaning |
---|---|
SUCCESS | The function was successful. |
<1 | An error occurred. Refer to Return Codes. |
This function supports 8 and 16-bit grayscale images.
Win32, x64, Linux.
This example loads a bitmap and applies an CLAHE filter.
L_INT CLAHEBitmapExample(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("DICOM\\IMAGE3.dcm")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGRORGRAY, NULL, NULL);
if (nRet != SUCCESS)
return nRet;
/* Apply a CLAHE filter */
nRet = L_CLAHE(&LeadBitmap, 0.5f, 9, 0.04f, 512, CLAHE_RAYLIEH);
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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