php 如何将所有图像转换为jpg？
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How can I convert all images to jpg?
提问by Steven Sacradoor
I have script:
我有脚本：
<?php
include('db.php');
session_start();
$session_id = '1'; // User session id
$path = "uploads/";
$valid_formats = array("jpg", "png", "gif", "bmp", "jpeg");
if (isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST") {
$name = $_FILES['photoimg']['name'];
$size = $_FILES['photoimg']['size'];
if (strlen($name)) {
list($txt, $ext) = explode(".", $name);
if (in_array($ext, $valid_formats)) {
if ($size < (1024 * 1024)) { // Image size max 1 MB
$actual_image_name = time() . $session_id . "." . $ext;
$tmp = $_FILES['photoimg']['tmp_name'];
if (move_uploaded_file($tmp, $path . $actual_image_name)) {
mysql_query("UPDATE users SET profile_image='$actual_image_name' WHERE uid='$session_id'");
echo "<img src='uploads/" . $actual_image_name . "' class='preview'>";
} else {
echo "failed";
}
} else {
echo "Image file size max 1 MB";
}
} else {
echo "Invalid file format..";
}
} else {
echo "Please select image..!";
}
exit;
}
?>
Is possible convert all images (png, gif etc) to jpg with 100% quality? If yes, how? I would like allow to upload png and gif, but this script should convert this files to jpg. Is possible this with PHP?
是否可以将所有图像（png、gif 等）转换为 100% 质量的 jpg？如果是，如何？我想允许上传 png 和 gif，但此脚本应将此文件转换为 jpg。这可以用 PHP 实现吗？
回答by Davide Berra
Try this code: originalImageis the path of... the original image... outputImageis self explaining enough. Qualityis a number from 0 to 100 setting the output jpg quality (0 - worst, 100 - best)
试试这个代码：originalImage是......原始图像的路径......outputImage自我解释就足够了。Quality是一个从 0 到 100 的数字，设置输出 jpg 质量（0 - 最差，100 - 最好）
function convertImage($originalImage, $outputImage, $quality)
{
// jpg, png, gif or bmp?
$exploded = explode('.',$originalImage);
$ext = $exploded[count($exploded) - 1];
if (preg_match('/jpg|jpeg/i',$ext))
$imageTmp=imagecreatefromjpeg($originalImage);
else if (preg_match('/png/i',$ext))
$imageTmp=imagecreatefrompng($originalImage);
else if (preg_match('/gif/i',$ext))
$imageTmp=imagecreatefromgif($originalImage);
else if (preg_match('/bmp/i',$ext))
$imageTmp=imagecreatefrombmp($originalImage);
else
return 0;
// quality is a value from 0 (worst) to 100 (best)
imagejpeg($imageTmp, $outputImage, $quality);
imagedestroy($imageTmp);
return 1;
}
回答by chill0r
Try using ImagicksetImageFormat, for me it provides the best image quality
http://php.net/manual/en/imagick.setimageformat.php
尝试使用ImagicksetImageFormat，对我来说它提供了最好的图像质量
http://php.net/manual/en/imagick.setimageformat.php
$im = new imagick($image);
// convert to png
$im->setImageFormat('png');
//write image on server
$im->writeImage($image .".png");
$im->clear();
$im->destroy();
回答by Lucas Bustamante
Davide Berra's answer is great, so I improved the file type detection a little, using exif_imagetype()instead of relying on the file extension:
Davide Berra 的回答很棒，所以我稍微改进了文件类型检测，使用exif_imagetype()而不是依赖文件扩展名：
/**
* Auxiliar function to convert images to JPG
*/
function convertImage($originalImage, $outputImage, $quality) {
switch (exif_imagetype($originalImage)) {
case IMAGETYPE_PNG:
$imageTmp=imagecreatefrompng($originalImage);
break;
case IMAGETYPE_JPEG:
$imageTmp=imagecreatefromjpeg($originalImage);
break;
case IMAGETYPE_GIF:
$imageTmp=imagecreatefromgif($originalImage);
break;
case IMAGETYPE_BMP:
$imageTmp=imagecreatefrombmp($originalImage);
break;
// Defaults to JPG
default:
$imageTmp=imagecreatefromjpeg($originalImage);
break;
}
// quality is a value from 0 (worst) to 100 (best)
imagejpeg($imageTmp, $outputImage, $quality);
imagedestroy($imageTmp);
return 1;
}
You must have php_exifextension enabled to use this.
您必须启用php_exif扩展才能使用它。
回答by Ahmad Vaqas Khan
A small code to convert image.pngto image.jpgat desired image quality:
要转换image.png为image.jpg所需图像质量的小代码：
<?php
$image = imagecreatefrompng('image.png');
imagejpeg($image, 'image.jpg', 70); // 0 = worst / smaller file, 100 = better / bigger file
imagedestroy($image);
?>
回答by Roy B. xSITE
a small fix to davide's answer, the correct function for converting from BMP is "imagecreatefromwbmp" instead of imagecreatefrombmp (missing "w") also you should consider that png may be transparent, here isa way to fill it with white BG (jpeg can't apply alpha data).
大卫的答案的一个小修正，从BMP转换的正确函数是“imagecreatefrom wbmp”而不是imagecreatefrombmp（缺少“w”）你也应该考虑png可能是透明的，这是一种用白色BG填充它的方法（ jpeg 不能应用 alpha 数据）。
function convertImage($originalImage, $outputImage, $quality){
// jpg, png, gif or bmp?
$exploded = explode('.',$originalImage);
$ext = $exploded[count($exploded) - 1];
if (preg_match('/jpg|jpeg/i',$ext)){$imageTmp=imagecreatefromjpeg($originalImage);}
else if (preg_match('/png/i',$ext)){$imageTmp=imagecreatefrompng($originalImage);}
else if (preg_match('/gif/i',$ext)){$imageTmp=imagecreatefromgif($originalImage);}
else if (preg_match('/bmp/i',$ext)){$imageTmp=imagecreatefromwbmp($originalImage);}
else { return false;}
// quality is a value from 0 (worst) to 100 (best)
imagejpeg($imageTmp, $outputImage, $quality);
imagedestroy($imageTmp);
return true;
}
回答by Anton Moskalenko
From PhpTools:
来自 PHPTools：
/**
* @param string $source (accepted jpg, gif & png filenames)
* @param string $destination
* @param int $quality [0-100]
* @throws \Exception
*/
public function convertToJpeg($source, $destination, $quality = 100) {
if ($quality < 0 || $quality > 100) {
throw new \Exception("Param 'quality' out of range.");
}
if (!file_exists($source)) {
throw new \Exception("Image file not found.");
}
$ext = pathinfo($source, PATHINFO_EXTENSION);
if (preg_match('/jpg|jpeg/i', $ext)) {
$image = imagecreatefromjpeg($source);
} else if (preg_match('/png/i', $ext)) {
$image = imagecreatefrompng($source);
} else if (preg_match('/gif/i', $ext)) {
$image = imagecreatefromgif($source);
} else {
throw new \Exception("Image isn't recognized.");
}
$result = imagejpeg($image, $destination, $quality);
if (!$result) {
throw new \Exception("Saving to file exception.");
}
imagedestroy($image);
}
