imagecreatetruecolor（）使我的图像质量下降 [英] imagecreatetruecolor() makes my image lose quality

问题描述

我正在使用以下脚本根据上传图片的人创建JPG。会发生的是，即使图像的宽度/高度完全相同，它仍然会失去质量以至于无法接受。

I'm using the script below to create an JPG based on people uploading an image. What happens is that even if an image is the exact same width/height it still loses quality so much that it's unacceptable.

$im = imagecreatefromjpeg($_FILES['cpicture']['tmp_name']);
$thumb=imagecreatetruecolor(507,307);
ImageCopyResampled($thumb,$im,0,0,0,0,$newwidth,$newheight,ImageSX($im),ImageSY($im));
ImagejpeG($thumb,"uploads/".$randomvalue.".jpg");
$imgurl="uploads/".$randomvalue.".jpg";

这些功能会降低质量吗？

Are these functions reducing the quality?

推荐答案

imagejpeg 第三个参数是要输出的图像的质量：

imagejpeg's third parameter is the quality of the image to be output:

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）。

quality is optional, and ranges from 0 (worst quality, smaller file) to 100 (best quality, biggest file). The default is the default IJG quality value (about 75).

尝试将代码的相关行更改为：

Try changing the relevant line of your code to:

ImagejpeG($thumb,"uploads/".$randomvalue.".jpg", 100);

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