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php method to modify the image pixels: first create a PHP sample file; then modify the image pixel size through "function resize_image($filename, $newx, $newy, $ext){...}" .
The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer
PHP changes the pixel size of the picture
The following are methods and usage examples for modifying images to specified pixels:
/** * @Desc: * @DateTime: xxx * @param $filename 文件名(所在路径) * @param $xmax 修改后最大宽度 * @param $ymax 修改后最大高度 * @param $ext 文件后缀 * @return resource */ function resize_image($filename, $newx, $newy, $ext) { //根据后缀,由文件或 URL 创建一个新图象(内置函数) if($ext == "jpg" || $ext == "jpeg") $im = imagecreatefromjpeg($filename); elseif($ext == "png") $im = imagecreatefrompng($filename); elseif($ext == "gif") $im = imagecreatefromgif($filename); //获取当前待修改图片像素(内置函数) $x = imagesx($im); $y = imagesy($im); //新建一个真彩色图像(内置函数) $im2 = imagecreatetruecolor($newx, $newy); //重采样拷贝部分图像并调整大小(内置函数) imagecopyresampled($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y); return $im2; } //使用示例: $tmp = './img/test.jpg';//图片文件所在路径,相对路径和绝对路径都行 $fileinfo = pathinfo($tmp); $ext = $fileinfo['extension']; $image = resize_image($tmp, 1242, 2208, $ext); if($ext == "jpg" || $ext == "jpeg") imagejpeg($image, $tmp); elseif($ext == "png") imagepng($image, $tmp); elseif($ext == "gif") imagegif($image, $tmp);
After the script is executed, the original image will be replaced with the modified image. The implementation logic can be reasonably modified according to the business.
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