Predefined
Definition
Assembly: KGySoft.Drawing.Core (in KGySoft.Drawing.Core.dll) Version: 9.0.0
public static PredefinedColorsQuantizer SystemDefault8BppPalette(
Color32 backColor = default,
byte alphaThreshold = 128
)Public Shared Function SystemDefault8BppPalette (
Optional backColor As Color32 = Nothing,
Optional alphaThreshold As Byte = 128
) As PredefinedColorsQuantizerpublic:
static PredefinedColorsQuantizer^ SystemDefault8BppPalette(
Color32 backColor = Color32(),
unsigned char alphaThreshold = 128
)static member SystemDefault8BppPalette :
?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), whose Color32.A field
is equal to or greater than alphaThreshold 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 transparent.
If 0, then the quantized colors will never be transparent. This parameter is optional.
Default value: 128.
Return Value
PredefinedColorsQuantizerA PredefinedColorsQuantizer instance that can quantize colors using the system default 8-bit palette.
Remarks
The returned PredefinedColorsQuantizer instance can return up to 256 colors. Actually this amount is somewhat smaller because of some redundant entries in the palette.
This quantizer fits well for the Format8bppIndexed pixel format.
The palette of this quantizer contains transparent entries.
Examples
public static IReadWriteBitmapData ToDefault8Bpp(IReadWriteBitmapData source, Color32 backColor = default,
byte alphaThreshold = 128, IDitherer ditherer = null)
{
IQuantizer quantizer = PredefinedColorsQuantizer.SystemDefault8BppPalette(backColor, alphaThreshold);
// a.) this solution returns a new bitmap data and does not change the original one:
return source.Clone(KnownPixelFormat.Format8bppIndexed, quantizer, ditherer);
// b.) when converting to Format8bppIndexed format without dithering, this produces the same result:
if (ditherer == null)
return source.Clone(KnownPixelFormat.Format8bppIndexed, backColor, alphaThreshold);
// c.) 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:
Original image | Quantized image |
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