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wiImage::asPalette()

See: List of operations

Signature

wiImage::asPalette($nColors = 255, $dither = null, $matchPalette = true)

Parameters

result (wiPaletteImage): a palette image

Description

Returns a copy of itself, converted to wiPaletteImage. $nColors specifies the number of colors (max 255), $dither enables/disables mixdown dithering, $matchPalette specifies whether the palette should be corrected with imagecolormatch()∞ after converting to a palette image.

Notes

For wiPaletteImage objects, this returns an ordinary copy.

As for $dither and $matchPalette, I've played with these two a lot and I'm not sure what are the best settings. This is what I found out (your experience may differ):

If you want to retain a single-color transparency information (not alpha channel), use $dither = true.
$matchPalette can improve the image quality, bun can affect transparency.

Examples

// load a truecolor png and save it as an 8-bit gif with dithering and no palette matching

$img = wiImage::load('/path/to/an/image.png');

$img->asPalette(255, true, false)->saveToFile('palette-image.png');