Function.imagetruecolortopalette

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imagetruecolortopalette — Convert a true color image to a palette image

Beschreibung

bool imagetruecolortopalette ( resource $image , bool $dither , int $ncolors )

imagetruecolortopalette() converts a truecolor image to a palette image. The code for this function was originally drawn from the Independent JPEG Group library code, which is excellent. The code has been modified to preserve as much alpha channel information as possible in the resulting palette, in addition to preserving colors as well as possible. This does not work as well as might be hoped. It is usually best to simply produce a truecolor output image instead, which guarantees the highest output quality.

Parameter-Liste

image

• Eine von den verschiedenen Erzeugungsfunktionen wie imagecreatetruecolor() gelieferte Grafikresource.

dither

• Indicates if the image should be dithered - if it is TRUE then dithering will be used which will result in a more speckled image but with better color approximation.

ncolors

• Sets the maximum number of colors that should be retained in the palette.

Rückgabewerte

Gibt bei Erfolg TRUE zurück, im Fehlerfall FALSE.

Beispiele

Beispiel #1 Converting a true color image to a palette-based image

<?php
// Create a new true color image
$im = new imagecreatetruecolor(100, 100);
 
// Convert to palette-based with no dithering and 255 colors
imagetruecolortopalette($im, false, 255);
 
// Save the image
imagepng($im, './paletteimage.png');
imagedestroy($im);
?>

Anmerkungen

Hinweis: Diese Funktion setzt die GD Bibliothek in der Version 2.0.1 oder höher (empfohlen wird mindestens 2.0.28) voraus.