L_SetPaintGamma

#include "l_bitmap.h"

L_LTDIS_API L_INT L_SetPaintGamma(pBitmap, uValue)

Sets the current gamma correction value for the specified bitmap. This value can be retrieved using the L_GetPaintGamma function.

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the bitmap to be affected.

L_UINT uValue

Unsigned integer that represents the gamma value. It can be any number greater than 0. The default value is 100.

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

Value Meaning
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.

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

Platforms

Win32, x64, Linux.

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