Declarations

procedure SetGamma; overload;
procedure SetGamma(Gamma: Double); overload;
procedure SetGamma(Gamma: Double; var GammaTable: TGammaTable8Bit); overload;

Overload Details

Overload 1

procedure SetGamma; overload;

Recalculated global gamma encoding and decoding tables using DEFAULT_GAMMA (1.6).

Overload 2

procedure SetGamma(Gamma: Double); overload;

Recalculates global gamma encoding and decoding tables using a specified power-law gamma exponent.

Parameter	Type	Description
Gamma	Double	Power-law gamma exponent (e.g. 1.6, 2.2).

Overload 3

procedure SetGamma(Gamma: Double; var GammaTable: TGammaTable8Bit); overload;

Populates a custom 256-byte lookup table with values calculated from a specified power-law gamma exponent.

Parameter	Type	Description
Gamma	Double	Power-law gamma exponent.
GammaTable	TGammaTable8Bit	Target 256-byte table array to receive calculated gamma values.

Description

SetGamma calculates power-law gamma transformation values for 8-bit color channels ($0\dots 255$).

• The single-value and parameterless overloads populate the global GAMMA_ENCODING_TABLE (using exponent $1/\gamma$) and GAMMA_DECODING_TABLE (using exponent $\gamma$), update GAMMA_VALUE, set GAMMA_IS_SRGB to False, and invoke delegates registered with RegisterGammaChangeNotification.
• The 3-parameter overload populates a custom TGammaTable8Bit array without modifying global state or firing change notifications.

Formula

For each entry $i\in [0\dots 255]$:

$$\text{GammaTable}[i]=\text{Round}(255\cdot {\left(\frac{i}{255}\right)}^{\gamma })$$

Example

// Set global power-law gamma to standard display gamma 2.2
SetGamma(2.2);

// Or generate a custom lookup table for custom image processing
var
  CustomTable: TGammaTable8Bit;
begin
  SetGamma(1.8, CustomTable);
  ApplyCustomGamma(MyBitmap, CustomTable);
end;

See also

• Set_sRGB
• GAMMA_VALUE
• GAMMA_IS_SRGB
• RegisterGammaChangeNotification