PHP GD Functions

DITHERING

is a technique used in computer graphics to create the illusion of color depth in images whose palette has a limited number of colors.

If $dither = TRUE then dithering will be used which will result in a more speckled image but with better color approximation.

This function returns TRUE on success or FALSE on failure.


<?php

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

where,

$image = An image identifier

$dither = To control if the image will be dithered or not

$num_colors = The maximun number of colors that 
                                     should be retained in the palette

?>

$image

The image identifier.

$dither

To control if the image will be dithered or not.

$num_colors

The maximun number of colors that should be retained in the palette.

EXERCISE


<?php

echo 'PHP VERSION: ' . PHP_VERSION . '<br><br>';

$lang = 'en';

$tst_img01 = "png/PNG 081 01.png";

$dst_img01 = "gif/GIF 027 01.gif";

$dith = TRUE;
$colors = 256;

$id_wv01 = imagecreatefrompng($tst_img01);

$is_tc = imageistruecolor($id_wv01);

if($is_tc == FALSE)
{
$en = '<br><br>Is not a TRUECOLOR IMAGE';

echo $tst_img01 . $$lang; ?>
<br><br><img src="<?php echo $tst_img01; ?>"
alt="<?php echo $tst_img01; ?>" width="400"><br><br><br><br>

<?php
}
else
{
$en = '<br><br>TRUECOLOR IMAGE';

echo $tst_img01 . $$lang; ?>
<br><br><img src="<?php echo 
$tst_img01; ?>" alt="<?php echo $tst_img01; ?>" width="400">
<br><br><br><br>

<?php

imagetruecolortopalette($id_wv01, $dith, $colors);

imagegif($id_wv01, $dst_img01);

$en = '<br><br>PALETTE IMAGE';

echo $dst_img01 . $$lang; ?>
<br><br><img src="<?php echo 
$dst_img01; ?>" alt="<?php echo $dst_img01; ?>" width="400"><br>

<?php
}

?>