imagetruecolortopalette

(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)

imagetruecolortopalette — Convert a true color image to a palette image

Descrizione

imagetruecolortopalette(GdImage $image, bool $dither, int $num_colors): bool

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.

Elenco dei parametri

image: Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().
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.
num_colors: Sets the maximum number of colors that should be retained in the palette.

Valori restituiti

Restituisce true in caso di successo, false in caso di fallimento.

Log delle modifiche

Versione	Descrizione
8.0.0	`image` expects a GdImage instance now; previously, a valid `gd` resource was expected.

Esempi

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

<?php
// Create a new true color image
$im = imagecreatetruecolor(100, 100);

// Convert to palette-based with no dithering and 255 colors
imagetruecolortopalette($im, false, 255);

// Save the image
imagepng($im, './paletteimage.png');
?>