In case you use default un-normalized getColor value the alpha value will always be either 0 or 1.
If you want to use real full-range 0-1 alpha channel on your 24bit transparent images use the alpha value from the normalized one, even if you use the rest of unnormalized data.
To copy a 24bit png with real alpha transparency, you would have to do this:
<?php
$im=new Imagick( 'image.png' );
$iterator=$im->getPixelIterator();
foreach ($iterator as $row=>$pixels) {
foreach ( $pixels as $column => $pixel ){
$un_color=$pixel->getColor(); //unnormalized color
$nor_color=$pixel->getColor(true); //normalized color
$pixel->setColor('rgba('.$un_color['r'].','.$un_color['g'].','.$un_color['b'].','.$nor_color['a'].')');
}
}
?>
If you use 'a' (alpha) value from the unnormalized color there will only be binary transparency.
ImagickPixel::getColor
(PECL imagick 2.0.0)
ImagickPixel::getColor — Returns the color
Opis
ImagickPixel::getColor
([ int
$normalized = 0
] ) : arrayReturns the color described by the ImagickPixel object, as an array. If the color has an opacity channel set, this is provided as a fourth value in the list.
Parametry
-
normalized -
Normalize the color values
Zwracane wartości
An array of channel values, each normalized if TRUE is given as param. Throws
ImagickPixelException on error.
Przykłady
Przykład #1 Basic Imagick::getColor() usage
<?php
//Create an ImagickPixel with the predefined color 'brown'
$color = new ImagickPixel('brown');
//Set the color to have an alpha of 25%
$color->setColorValue(Imagick::COLOR_ALPHA, 64 / 256.0);
$colorInfo = $color->getColor();
echo "Standard values".PHP_EOL;
print_r($colorInfo);
$colorInfo = $color->getColor(true);
echo "Normalized values:".PHP_EOL;
print_r($colorInfo);
?>
Powyższy przykład wyświetli:
Standard values
Array
(
[r] => 165
[g] => 42
[b] => 42
[a] => 0
)
Normalized values:
Array
(
[r] => 0.64705882352941
[g] => 0.16470588235294
[b] => 0.16470588235294
[a] => 0.25000381475547
)
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User Contributed Notes 1 note
roman ¶
10 years ago
