L_HistoContrastBitmap
#include "l_bitmap.h"
L_INT EXT_FUNCTION L_HistoContrastBitmap(pBitmap, nChange)
pBITMAPHANDLE pBitmap; |
/* pointer to the bitmap handle */ |
L_INT nChange; |
/* amount of contrast change */ |
Increases or decreases the contrast of the image in a bitmap, using a histogram to determine the median brightness.
Parameter |
Description |
pBitmap |
Pointer to the bitmap handle referencing the bitmap to be modified. |
nChange |
Amount of contrast change. Valid values are -1000 to +1000. |
Returns
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
Comments
This function finds the median brightness of the image; then brightens the pixels with values above the median and darkens the pixels with values below the median. This is more sophisticated (but slower) than the L_ChangeBitmapContrast function, which uses the middle possible value (128) rather than finding the actual median.
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 only in the Document/Medical toolkits.
Required DLLs and Libraries
LTIMG For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application. |
Platforms
Windows 95 / 98 / Me, Windows 2000 / XP.
See Also
Example
/* This example loads a bitmap and increases its contrast. */
BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the loaded image. */
/* Load the bitmap, keeping the bits per pixel of the file */
L_LoadBitmap (TEXT("IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
/* Increase the contrast using the histogram by 25 percent of the possible range */
L_HistoContrastBitmap(&LeadBitmap, 250 );