imagecolorclosestalpha
(PHP 4 >= 4.0.6, PHP 5)
imagecolorclosestalpha — Get the index of the closest color to the specified color + alpha
說明
int imagecolorclosestalpha
( resource
$image
, int $red
, int $green
, int $blue
, int $alpha
)
Returns the index of the color in the palette of the image which
is "closest" to the specified RGB value and
alpha level.
參數
-
image -
由影像建立函式(例如imagecreatetruecolor())回傳的影像資源。
-
red -
紅色成分的值。
-
green -
綠色成分的值。
-
blue -
藍色成分的值。
-
alpha -
A value between 0 and 127. 0 indicates completely opaque while 127 indicates completely transparent.
回傳值
Returns the index of the closest color in the palette.
範例
Example #1 Search for a set of colors in an image
<?php
// Start with an image and convert it to a palette-based image
$im = imagecreatefrompng('figures/imagecolorclosest.png');
imagetruecolortopalette($im, false, 255);
// Search colors (RGB)
$colors = array(
array(254, 145, 154, 50),
array(153, 145, 188, 127),
array(153, 90, 145, 0),
array(255, 137, 92, 84)
);
// Loop through each search and find the closest color in the palette.
// Return the search number, the search RGB and the converted RGB match
foreach($colors as $id => $rgb)
{
$result = imagecolorclosestalpha($im, $rgb[0], $rgb[1], $rgb[2], $rgb[3]);
$result = imagecolorsforindex($im, $result);
$result = "({$result['red']}, {$result['green']}, {$result['blue']}, {$result['alpha']})";
echo "#$id: Search ($rgb[0], $rgb[1], $rgb[2], $rgb[3]); Closest match: $result.\n";
}
imagedestroy($im);
?>
上例的輸出類似於：
#0: Search (254, 145, 154, 50); Closest match: (252, 150, 148, 0). #1: Search (153, 145, 188, 127); Closest match: (148, 150, 196, 0). #2: Search (153, 90, 145, 0); Closest match: (148, 90, 156, 0). #3: Search (255, 137, 92, 84); Closest match: (252, 150, 92, 0).
註釋
Note: 本函式需要 GD 2.0.1 或更高版本（推薦 2.0.28 及更高版本）。
參見
- imagecolorexactalpha() - Get the index of the specified color + alpha
- imagecolorclosest() - Get the index of the closest color to the specified color
- imagecolorclosesthwb() - Get the index of the color which has the hue, white and blackness
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