PredefinedColorsQuantizerRgb888 Method

public static PredefinedColorsQuantizer Rgb888(
	Color32 backColor = default,
	byte alphaThreshold = 128
)

Public Shared Function Rgb888 ( 
	Optional backColor As Color32 = Nothing,
	Optional alphaThreshold As Byte = 128
) As PredefinedColorsQuantizer

public:
static PredefinedColorsQuantizer^ Rgb888(
	Color32 backColor = Color32(), 
	unsigned char alphaThreshold = 128
)

static member Rgb888 : 
        ?backColor : Color32 * 
        ?alphaThreshold : byte 
(* Defaults:
        let _backColor = defaultArg backColor new Color32()
        let _alphaThreshold = defaultArg alphaThreshold 128
*)
-> PredefinedColorsQuantizer 

Parameters

backColor  Color32  (Optional)

Colors with alpha (transparency) will be blended with this color before quantizing. The Color32.A field of the background color is ignored. This parameter is optional.
Default value: The default value of the Color32 type, which has the same RGB values as Color.Black.

alphaThreshold  Byte  (Optional)

Specifies a threshold value for the Color32.A field, under which a quantized color is considered completely transparent. Though the quantizer returned from this method never returns alpha colors, it can be relevant in some cases, for example when drawing a partially transparent bitmap onto a solid background. The source pixels, whose alpha value is below the alphaThreshold will be skipped, whereas alpha pixels with higher opacity will be blended with the specified backColor. This parameter is optional.
Default value: 128.

Return Value

The returned PredefinedColorsQuantizer instance can return up to 256³ (16,777,216) colors. It practically just removes transparency and does not change colors without alpha.

This quantizer fits well for the Format24bppRgb pixel format.

public static IReadWriteBitmapData ToRgb888(IReadWriteBitmapData source, Color32 backColor = default)
{
    IQuantizer quantizer = PredefinedColorsQuantizer.Rgb888(backColor);

    // a.) this solution returns a new bitmap data and does not change the original one:
    return source.Clone(KnownPixelFormat.Format24bppRgb, quantizer);

    // b.) when converting to Format24bppRgb format, this produces the same result:
    return source.Clone(KnownPixelFormat.Format24bppRgb, backColor);

    // c.) alternatively, you can perform the quantizing directly on the source bitmap data:
    source.Quantize(quantizer);
    return source;
}

The example above may produce the following results:

Reference