PredefinedColorsQuantizerBlackAndWhite Method

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

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

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

static member BlackAndWhite : 
        ?backColor : Color32 * 
        ?whiteThreshold : byte * 
        ?alphaThreshold : byte 
(* Defaults:
        let _backColor = defaultArg backColor new Color32()
        let _whiteThreshold = defaultArg whiteThreshold 128
        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.

whiteThreshold  Byte  (Optional)

Specifies a threshold value for the brightness of the colors, under which a quantized color is considered black. If 0, then the complete result will be white. This parameter is optional.
Default value: 128.

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

If the returned quantizer is combined with an ErrorDiffusionDitherer, then the effect of the whiteThreshold parameter is mostly compensated. Other ditherers preserve the effect of the whiteThreshold parameter.

This quantizer fits well for the Format1bppIndexed pixel format.

public static IReadWriteBitmapData ToBlackAndWhite(IReadWriteBitmapData source, Color32 backColor = default,
    byte whiteThreshold = 128, IDitherer ditherer = null)
{
    IQuantizer quantizer = PredefinedColorsQuantizer.BlackAndWhite(backColor, whiteThreshold);

    // a.) this solution returns a new bitmap data and does not change the original one:
    return source.Clone(KnownPixelFormat.Format1bppIndexed, quantizer, ditherer);

    // b.) alternatively, you can perform the quantizing directly on the source bitmap data:
    if (ditherer == null)
        source.Quantize(quantizer);
    else
        source.Dither(quantizer, ditherer);
    return source;
}

The example above may produce the following results:

Reference