BGRABitmap Pixel types

List of pixel types and functions of BGRABitmap library. They are provided by BGRABitmapTypes unit.

Pixel types and functions

PBGRAPixel = ^TBGRAPixel;

Pointer for direct pixel access. Data is stored as a sequence of TBGRAPixel. See Tutorial 4

TBGRAPixel = packed record

Each pixel is a sequence of 4 bytes containing blue, green, red and alpha channel. Values range from 0 to 255, color is in sRGB colorspace. The alpha value of 0 is transparent and 255 is opaque. In the bitmap data, when the pixel is fully transparent, the RGB values are supposed to be set to zero.

red, green, blue, alpha: byte;

Fields if ordered RGBA ordered

blue, green, red, alpha: byte;

Fields if ordered BGRA ordered

procedure FromRGB(ARed,AGreen,ABlue: Byte; AAlpha: Byte = 255);

Sets the pixel with given RGB values

procedure FromColor(AColor: TColor; AAlpha: Byte = 255);

Sets the pixel with given TColor

procedure FromString(AStr: string);

Sets the pixel according to a color name or CSS expression

procedure FromFPColor(AColor: TFPColor);

Sets the pixel with given TFPColor (16-bit per channel)

procedure ToRGB(out ARed,AGreen,ABlue,AAlpha: Byte); overload;

Extras RGBA channels

procedure ToRGB(out ARed,AGreen,ABlue: Byte); overload;

Extras RGB channels

function ToColor: TColor;

Converts to TColor

function ToString: string;

Converts to a CSS string representation

function ToGrayscale(AGammaCorrection: boolean = true): TBGRAPixel;

Compute grayscale equivalent

function ToFPColor: TFPColor;

Converts to TFPColor (16-bit per channel)

function EqualsExactly(constref AColor: TBGRAPixel): boolean;

Check whether all channels are equal (this is generally not necessary to use this fonction unless the RGB value of a transparent color matter)

class operator := (Source: TBGRAPixel): TColor;

Assign a TBGRAPixel to a TColor

class operator := (Source: TColor): TBGRAPixel;

Assign a TColor to a TBGRAPixel

property Intensity: word read GetClassIntensity write SetClassIntensity;

Intensity of the color (how much channels are saturated)

property Lightness: word read GetClassLightness write SetClassLightness;

Lightness of the color (the resulting lightness of combined channels)

operator = (const c1, c2: TBGRAPixel): boolean; inline;

Checks if two pixels are equal. If they are both transparent, RGB values are ignored

const TBGRAPixel_RGBAOrder = False;

Order of the channels (when BGRA)

const TBGRAPixel_BlueByteOffset = 0;

Offset of the blue channel (when BGRA)

const TBGRAPixel_GreenByteOffset = 1;

Offset of the green channel (when BGRA)

const TBGRAPixel_RedByteOffset = 2;

Offset of the blue channel (when BGRA)

const TBGRAPixel_AlphaByteOffset = 3;

Offset of the alpha channel

function BGRA(red, green, blue, alpha: byte): TBGRAPixel; overload; inline;

Creates a pixel with given RGBA values

function BGRA(red, green, blue: byte): TBGRAPixel; overload; inline;

Creates a opaque pixel with given RGB values

function GetIntensity(c: TBGRAPixel): word; inline;

Returns the intensity of a pixel. The intensity is the maximum value reached by any component

function SetIntensity(c: TBGRAPixel; intensity: word): TBGRAPixel;

Sets the intensity of a pixel

function GetLightness(c: TBGRAPixel): word; overload;

Returns the lightness of a pixel. The lightness is the perceived brightness, 0 being black and 65535 being white

function SetLightness(c: TBGRAPixel; lightness: word): TBGRAPixel; overload;

Sets the lightness of a pixel

function ApplyLightnessFast(color: TBGRAPixel; lightness: word): TBGRAPixel; inline;

Sets the lightness quickly, by fading towards black if lightness is less than 32768, and fading towards white if lightness is more than 32768

function ApplyIntensityFast(color: TBGRAPixel; lightness: LongWord): TBGRAPixel;

Sets the intensity quickly, by fading towards black if lightness is less than 32768, and multiplying all components if lightness is more than 32768. In case of saturation, it fades towards white

function CombineLightness(lightness1,lightness2: Int32or64): Int32or64;

Combines two lightnesses together. A value of 32768 is neutral. The result may exceed 65535

function BGRAToGrayscale(c: TBGRAPixel): TBGRAPixel;

Converts a color into grayscale

function BGRAToGrayscaleLinear(c: TBGRAPixel): TBGRAPixel;

Converts a color into grayscale assuming linear colorspace

function GrayscaleToBGRA(lightness: word): TBGRAPixel;

Create a gray color with the given lightness

function MergeBGRA(c1, c2: TBGRAPixel): TBGRAPixel; overload;

Merge two colors without gamma correction

function MergeBGRA(c1: TBGRAPixel; weight1: integer; c2: TBGRAPixel; weight2: integer): TBGRAPixel; overload;

Merge two colors without gamma correction. weight1 and weight2 indicates the weight of the color barycentre

function MergeBGRAWithGammaCorrection(c1: TBGRAPixel; weight1: byte; c2: TBGRAPixel; weight2: byte): TBGRAPixel;

Merge two colors with gamma correction. weight1 and weight2 indicates the weight of the color barycentre

function ColorToBGRA(color: TColor): TBGRAPixel; overload;

Converts a TColor value into an opaque pixel

function ColorToBGRA(color: TColor; opacity: byte): TBGRAPixel; overload;

Converts a TColor value into a pixel with given opacity

function BGRAToColor(c: TBGRAPixel): TColor;

Converts a pixel into a TColor value, discarding the alpha value

function FastRoundDiv257(valueWord: LongWord): byte; inline;

Fonction to divide by 257 (not quite the same as shr 8)

function FPColorToBGRA(AValue: TFPColor): TBGRAPixel;

Converts a TFPColor value into a pixel. Note that even if TFPColor have 16-bit values, they are not considered as gamma expanded

function BGRAToFPColor(AValue: TBGRAPixel): TFPColor; inline;

Converts a pixel into a TFPColor

function Color16BitToBGRA(AColor: Word): TBGRAPixel;

Converts a 16-bit packed color into a TBGRAPixel

function BGRAToColor16Bit(const AColor: TBGRAPixel): Word;

Converts a TBGRAPixel into a 16-bit packed color

function BGRAWordDiff(c1, c2: TBGRAPixel): word;

Computes the difference (with gamma correction) between two pixels, taking into account all dimensions, including transparency. The result ranges from 0 to 65535

function BGRADiff(c1, c2: TBGRAPixel): byte;

Computes the difference (with gamma correction) between two pixels, taking into account all dimensions, including transparency. The result ranges from 0 to 255

function FastBGRALinearDiff(c1,c2: TBGRAPixel): byte;

Fast computation of difference, without weighing the alpha channel and without gamma correction

function FastBGRAExpandedDiff(c1,c2: TBGRAPixel): word;

Fast computation of difference, without weighing the alpha channel

function MapHeight(Color: TBGRAPixel): Single;

Get height [0..1] stored in a TBGRAPixel

function MapHeightToBGRA(Height: Single; Alpha: Byte): TBGRAPixel;

Get TBGRAPixel to store height [0..1]

TBGRAPixelBuffer = packed array of TBGRAPixel;

Array of TBGRAPixel to be used as a buffer

procedure AllocateBGRAPixelBuffer(var ABuffer: TBGRAPixelBuffer; ASize: integer);

Allocate a buffer of TBGRAPixel

ArrayOfTBGRAPixel = array of TBGRAPixel;

Array of pixels, not to be used as a buffer

function MergeBGRA(const colors: array of TBGRAPixel): TBGRAPixel; overload;

Merge given colors without gamma correction

TDrawMode = (

Possible modes when drawing a pixel over another one

dmSet,

The pixel is replaced

dmSetExceptTransparent,

The pixel is replaced if the pixel over has an alpha value of 255

dmLinearBlend,

The pixel is blend over the other one according to alpha values, however no gamma correction is applied. In other words, the color space is assumed to be linear

dmDrawWithTransparency,

The pixel is blend over the other one according to alpha values, and a gamma correction is applied. In other word, the color space is assumed to be sRGB

dmXor);

Values of all channels are combined with Xor. This is useful to compute the binary difference, however it is not something that makes much sense to display on the screen

dmFastBlend = dmLinearBlend;

An alias for the linear blend, because it is faster than blending with gamma correction

TBlendOperation = (

Advanced blending modes. See Paint.NET blend modes and Formulas. Blending layers has two steps. The first one is to apply the blend operations listed below, and the second is the actual merging of the colors

boLinearBlend,

Simple blend, except that it forces a linear merge so it is equivalent to dmLinearBlend

boTransparent,

Simple blend. It is equivalent to dmLinearBlend or dmDrawWithTransparency

boLighten, boScreen, boAdditive, boLinearAdd, boColorDodge, boDivide, boNiceGlow, boSoftLight, boHardLight,

Lighting blend modes (tends to increase the luminosity)

boGlow, boReflect, boOverlay, boDarkOverlay, boDarken, boMultiply, boColorBurn,

Masking blend modes (tends to decrease the luminosity)

boDifference, boLinearDifference, boExclusion, boLinearExclusion, boSubtract, boLinearSubtract, boSubtractInverse, boLinearSubtractInverse,

Difference blend modes

boNegation, boLinearNegation,

Negation blend modes

boXor,

Xor blend mode. It is sightly different from dmXor because the alpha value is used like in other blends modes

boSvgSoftLight,

SVG implementation of soft light

boMask,

Apply mask

boLinearMultiplySaturation, boLinearHue, boLinearColor, boLinearLightness, boLinearSaturation,

Standard HSL colorspace

boCorrectedHue, boCorrectedColor, boCorrectedLightness, boCorrectedSaturation

Corrected HSL colorspace (GSB)

boGlowMask = boGlow;

Alias to glow that express that this blend mode masks the part where the top layer is black

boLinearMultiply = boMultiply;

Alias because linear or non linear multiply modes are identical

boNonLinearOverlay = boDarkOverlay;

Alias to express that dark overlay is simply an overlay with gamma correction

BlendOperationStr : array[TBlendOperation] of string

String constants for blend modes

function StrToBlendOperation(str: string): TBlendOperation;

Returns the blend mode expressed by the string

TAlphaChannelPaletteOption = (

Specifies how a palette handles the alpha channel

acIgnore,

The alpha channel is ignored. The alpha channel is considered to be stored elsewhere

acTransparentEntry,

One entry is allocated the fully transparent color

acFullChannelInPalette);

The alpha channel is fully embedded in the palette so that a color is identified by its four RGBA channels

TDitheringAlgorithm = (

Dithering algorithms that specifies how to handle colors that are not found in the palette

daNearestNeighbor,

The nearest color is to be used instead

daFloydSteinberg);

The nearest color may be used however another color may be used to compensate for the error, following Floyd-Steinberg algorithm

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From the Free Pascal wiki, page "BGRABitmap Pixel types", as it stood on 2023-12-14 after a change by Circular, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's Licensing page. If you have concerns about this material, message the admin.