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

Functions:	L_ChangeBitmapIntensity, L_GammaCorrectBitmap, L_ChangeBitmapContrast, L_StretchBitmapIntensity, L_RemapBitmapIntensity, L_InvertBitmap, L_ChangeBitmapHue, L_ChangeBitmapSaturation, L_HistoEqualizeBitmap, L_FillBitmap, L_GetPixelColor, L_PutPixelColor, L_GetBitmapHistogram, L_DlgHistoContrast, L_WindowLevel, L_ChannelMix, L_DeinterlaceBitmap, L_DesaturateBitmap, L_EdgeDetectStatisticalBitmap, L_LightControlBitmap, L_SmoothEdgesBitmap, L_LocalHistoEqualizeBitmap, L_AddWeightedBitmaps, L_ColorMergeBitmap, L_ColorSeparateBitmap, L_ConvertColorSpace, L_MultiplyBitmap, L_AutoColorLevelBitmap, L_ColorLevelBitmap, L_CorrelationBitmap, L_GrayScaleToDuotone, L_GrayScaleToMultitone, L_HolesRemovalBitmapRgn, L_SelectiveColorBitmap, L_SkeletonBitmap, L_ChangeHueSatIntBitmap, L_ColorReplaceBitmap, L_ColorThresholdBitmap, L_MathFunctionBitmap, L_SegmentBitmap, L_AdaptiveContrastBitmap, L_ApplyMathLogicBitmap, L_ColorIntensityBalance, L_ColorizeGrayBitmap, L_ContBrightIntBitmap, L_DigitalSubtractBitmap, L_DynamicBinaryBitmap, L_EdgeDetectEffectBitmap, L_FunctionalLightBitmap, L_MultiScaleEnhancementBitmap, L_SelectBitmapData, L_ShiftBitmapData, L_AdjustBitmapTint, L_GammaCorrectBitmapExt
Topics:	Raster Image Functions: Modifying Intensity Values
	Changing Brightness and Contrast
	Raster Image Functions: Changing Brightness and Contrast

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 );