LBitmap::GammaCorrect

#include "ltwrappr.h"

virtual L_INT LBitmap::GammaCorrect(uGamma)

L_UINT uGamma;

/* unsigned integer that represents the gamma value */

Adjusts the intensity of colors in the class object's bitmap by changing the gamma constant that is used to map the intensity values.

Parameter

Description

uGamma

Unsigned integer that represents the gamma value. It can be any number greater than 0.

 

Because this is an unsigned integer, it is 100 times the actual gamma value. For example, use 235 to set a gamma value of 2.35.

Returns

SUCCESS

The function was successful.

< 1

An error occurred. Refer to Return Codes.

Comments

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 LBase::EnableStatusCallback.

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.

When applying contrast, gamma, and intensity changes to a bitmap, LEAD applies the changes in the following order:

Contrast

Intensity

Gamma

Required DLLs and Libraries

LTDIS
LTFIL
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:

LBitmap::AdjustTint, LBitmap::GammaCorrectExt, LBitmap::ChangeHue, LBitmap::ChangeSaturation, LBitmap::HistoContrast, LBitmap::StretchIntensity, LBitmap::RemapIntensity, LBitmap::Invert, LBitmap::ChangeContrast, LBitmap::ChangeIntensity, LBitmap::HistoEqualize, LBitmap::GetHistogram, LBitmap::WindowLevel, LBitmapBase::Fill, LBitmapBase::GetPixelColor, LBitmapBase::PutPixelColor, Class Members

Topics:

Raster Image Functions: Modifying Intensity Values

 

Changing Brightness and Contrast

 

Raster Image Functions: Changing Brightness and Contrast

Example

LBitmap LeadBitmap;
LeadBitmap.Load(TEXT("V:\\images\\babe.cmp"), 0,ORDER_BGR);
LeadBitmap.GammaCorrect(235);