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我目前正在研究需要分析多个图像并找出它们最接近的颜色的应用程序。带透明度的PHP图像颜色分析
因此，我发现了一个代码段正是如此：
function analyzeImageColors($im, $xCount =3, $yCount =3)
{
//get dimensions for image
$imWidth =imagesx($im);
$imHeight =imagesy($im);
//find out the dimensions of the blocks we're going to make
$blockWidth =round($imWidth/$xCount);
$blockHeight =round($imHeight/$yCount);
//now get the image colors...
for($x =0; $x<$xCount; $x++) { //cycle through the x-axis
for ($y =0; $y<$yCount; $y++) { //cycle through the y-axis
//this is the start x and y points to make the block from
$blockStartX =($x*$blockWidth);
$blockStartY =($y*$blockHeight);
//create the image we'll use for the block
$block =imagecreatetruecolor(1, 1);
//We'll put the section of the image we want to get a color for into the block
imagecopyresampled($block, $im, 0, 0, $blockStartX, $blockStartY, 1, 1, $blockWidth, $blockHeight);
//the palette is where I'll get my color from for this block
imagetruecolortopalette($block, true, 1);
//I create a variable called eyeDropper to get the color information
$eyeDropper =imagecolorat($block, 0, 0);
$palette =imagecolorsforindex($block, $eyeDropper);
$colorArray[$x][$y]['r'] =$palette['red'];
$colorArray[$x][$y]['g'] =$palette['green'];
$colorArray[$x][$y]['b'] =$palette['blue'];
//get the rgb value too
$hex =sprintf("%02X%02X%02X", $colorArray[$x][$y]['r'], $colorArray[$x][$y]['g'], $colorArray[$x][$y]['b']);
$colorArray[$x][$y]['rgbHex'] =$hex;
//destroy the block
imagedestroy($block);
}
}
//destroy the source image
imagedestroy($im);
return $colorArray;
}
问题是每当我提供具有透明性的图像，GDLib consinders透明度为黑色，从而产生错误的（暗得多）输出比真的是这样。
例如该图标，其中围绕箭头的白色区域实际上是透明的：
example http://img651.imageshack.us/img651/995/screenshot20100122at113.png
谁能告诉我如何解决此问题？