L_GammaCorrectBitmapExt

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_GammaCorrectBitmapExt(pBitmap, uGamma, uFlag)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_UINT uGamma;	/* gamma value */
L_UINT uFlag;	/* flag */

Adjusts the intensity of colors in a bitmap by changing the gamma constant that is used to map the intensity values. Either of two different color spaces can be specified.

Parameter	Description
pBitmap	Pointer to the bitmap handle referencing the target bitmap.
uGamma	Any value greater than 0 that represents the gamma value. This value is divided internally by 100.
uFlag	Flag that indicates which color space to use. Possible values are:
	Value	Meaning
	RGB_SPACE	[0x0001] Adjust the intensity of the pixel colors across the RGB color space.
	YUV_SPACE	[0x0002] Adjust the intensity of the pixel colors across the YUV color space.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

This function is like the L_GammaCorrectBitmap function, but has been extended to allow the specification of the colorspace to be used.

Intensity values ideally follow a logarithmic progression, because the eye perceives changes in intensity as being equal when the ratio of change is equal. For example, we would see a change from 0.1 to 0.2 as being equal to a change from 0.2 to 0.4.

Gamma is a standard constant that is used to calculate the progression. For most CRTs the gamma constant is in the range of 2.2 to 2.5.

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.

See Also

Functions:	L_GammaCorrectBitmap, L_ChangeBitmapIntensity, L_ChangeBitmapContrast, L_HistoContrastBitmap, L_StretchBitmapIntensity, L_RemapBitmapIntensity, L_InvertBitmap, L_ChangeBitmapHue, L_ChangeBitmapSaturation, L_HistoEqualizeBitmap, L_FillBitmap, L_GetPixelColor, L_PutPixelColor, L_GetBitmapHistogram, L_DlgGammaAdjustment, 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
Topics:	Raster Image Functions: Modifying Intensity Values
	Changing Brightness and Contrast
	Raster Image Functions: Changing Brightness and Contrast

Example

/* The following example sets the gamma value of the bitmap to 2.5 in the YUV color space: */
BITMAPHANDLE LeadBitmap;
L_LoadBitmap (TEXT("IMAGE1.CMP"), &LeadBitmap,sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
L_GammaCorrectBitmapExt (&LeadBitmap, 250, YUV_SPACE);