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.
Parameters
image
An image resource, returned by one of the image creation functions,
such as 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.
ncolors
Sets the maximum number of colors that should be retained in the palette.
Return Values
Returns TRUE on success or FALSE on failure.
Examples
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($im, './paletteimage.png'); imagedestroy($im); ?>