php man page for imagetruecolortopalette

IMAGETRUECOLORTOPALETTE(3)						 1						IMAGETRUECOLORTOPALETTE(3)

imagetruecolortopalette - Convert a true color image to a palette image

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

DESCRIPTION
       imagetruecolortopalette(3) converts a truecolor image to a palette image. The code for this function was originally drawn from the Indepen-
       dent 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
	      o $
		image -An image resource, returned by one of the image creation functions, such as imagecreatetruecolor(3).

	      o $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.

	      o $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);
	      ?>

NOTES
       Note

	      This function requires GD 2.0.1 or later (2.0.28 or later is recommended).

PHP Documentation Group 												IMAGETRUECOLORTOPALETTE(3)