Php 上传图像而不丢失质量
我使用这个类来上传和调整图像大小。问题是图像质量不好!我需要上传图像而不丢失任何质量Php 上传图像而不丢失质量,php,Php,我使用这个类来上传和调整图像大小。问题是图像质量不好!我需要上传图像而不丢失任何质量 class SimpleImage { var $image; var $image_type; function load($filename) { $image_info = getimagesize($filename); $this->image_type = $image_info[2]; if( $this->image_type
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 = $new_image;
}
}
有人能帮忙吗?您可以做的一件事是调用函数save 调用时,将质量参数从75更改为100
质量是可选的,范围从0(最差质量,较小文件)到100(最佳质量,最大文件)。默认值是默认的IJG质量值(约75) 我认为
75
是$compression
参数的默认值。将其作为的质量参数传递。这可能会导致质量损失。保存函数的默认质量值为75。因此,要么在调用它时将其更改为100,要么将默认值更改为100。100是最好的质量。注意imagepng
,因为它的数字是从9-0开始的(是的,向后)。我认为完美的图像90,但常规使用85是可以接受的值。质量问题已经解决,但还有一个问题。当我上传透明png图像时,透明部分变成黑色。如何解决此问题?请参见此处示例: