我正在使用以下类压缩图像。。
<?php
class SimpleImage {
var $image;
var $image_type;
function load($filename) {
$image_info = getimagesize($filename);
$this->image_type = $image_info[2];
if( $this->image_type == IMAGETYPE_JPEG ) {
$this->image = imagecreatefromjpeg($filename);
} elseif( $this->image_type == IMAGETYPE_GIF ) {
$this->image = imagecreatefromgif($filename);
} elseif( $this->image_type == IMAGETYPE_PNG ) {
$this->image = imagecreatefrompng($filename);
}
}
function save($filename,$image_type=IMAGETYPE_JPEG,$compression=75,$permissions=null){
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image,$filename,$compression);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image,$filename);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image,$filename);
}
if( $permissions != null) {
chmod($filename,$permissions);
}
}
function output($image_type=IMAGETYPE_JPEG) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image);
}
}
function getWidth() {
return imagesx($this->image);
}
function getHeight() {
return imagesy($this->image);
}
function resizeToHeight($height) {
$ratio = $height / $this->getHeight();
$width = $this->getWidth() * $ratio;
$this->resize($width,$height);
}
function resizeToWidth($width) {
$ratio = $width / $this->getWidth();
$height = $this->getheight() * $ratio;
$this->resize($width,$height);
}
function scale($scale) {
$width = $this->getWidth() * $scale/100;
$height = $this->getheight() * $scale/100;
$this->resize($width,$height);
}
function resize($width,$height) {
$new_image = imagecreatetruecolor($width, $height);
imagecopyresampled($new_image,$this->image,0,0,0,0,$width,$height,$this->getWidth(),$this->getHeight());
$this->image = $new_image;
}
}
?>
我的php代码看起来像。。
include_once(ROOT.'/library/SimpleImage.php')
$image = new SimpleImage();
$image->load($image_name);
$image->resizeToWidth(100);
$image->save($image_name);
现在的问题是，我的图像被压缩了，但它们原来的颜色组合丢失了。。。不知道该怎么办。。？？
请推荐另一个图像压缩类。
这是我很久以前编码的一个函数，它并没有真正优化，但它应该能做到。适用于各种mime类型，并允许您将修改后的图像保存到新位置。如果您需要较少的功能，您可以轻松地简化它。
public function resizePicture($path, $new_path, $new_width, $new_height, $proportion = false) {
$size = getimagesize($path);
$x = 0;
$y = 0;
switch($size['mime']) {
case 'image/jpeg':
$picture = imagecreatefromjpeg($path);
break;
case 'image/png':
$picture = imagecreatefrompng($path);
break;
case 'image/gif':
$picture = imagecreatefromgif($path);
break;
default:
return false;
break;
}
$width = $size[0];
$height = $size[1];
$frame = imagecreatetruecolor($new_width, $new_height);
if($size['mime'] == 'image/jpeg') {
$bg = imagecolorallocate($frame, 255, 255, 255);
imagefill($frame, 0, 0, $bg);
} else if($size['mime'] == 'image/gif' or $size['mime'] == 'image/png') {
imagealphablending($picture, false);
imagesavealpha($picture, true);
imagealphablending($frame, false);
imagesavealpha($frame, true);
}
if($width < $new_width and $height < $new_height) {
$x = ($new_width - $width) / 2;
$y = ($new_height - $height) / 2;
imagecopy($frame, $picture, $x, $y, 0, 0, $width, $height);
} else {
if($proportion and $width != $height) {
if($width > $height) {
$old_height = $new_height;
$new_height = $height * $new_width / $width;
$y = abs($old_height - $new_height) / 2;
} else {
$old_width = $new_width;
$new_width = $width * $new_height / $height;
$x = abs($old_width - $new_width) / 2;
}
}
imagecopyresampled($frame, $picture, $x, $y, 0, 0, $new_width, $new_height, $width, $height);
}
switch($size['mime']) {
case 'image/jpeg':
imagejpeg($frame, $new_path, 85);
break;
case 'image/png':
imagepng($frame, $new_path, 8);
break;
case 'image/gif':
imagegif($frame, $new_path);
break;
default:
return false;
break;
}
}
我使用SimpleImage.php，发现它是一个有用的小脚本，但我不得不在save函数中将$compression的值更改为100。
也许压缩某些格式可以减少颜色的数量，但通过将$compression设置为100，您可以告诉脚本"不要压缩！"之后，图像看起来就像他们想象的那样。