blocks|key|58698|text|This+article似乎可以满足您的需求。您需要将保存imagejpeg()函数更改为imagepng()，并让它将文件保存为字符串，而不是将其输出到页面，除此之外，还可以轻松地将其复制/粘贴到现有代码中。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|58699|entityMap|0|LINK|mutability|MUTABLE|url|http://www.phpit.net/article/image-manipulation-php-gd-part2/^0|0|C|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

<a href="http://www.phpit.net/article/image-manipulation-php-gd-part2/" rel="nofollow noreferrer">This article</a> seems like it would fit what you want. You'll need to change the saving imagejpeg() function to imagepng() and have it save the file to a string rather than output it to the page, but other than that it should be easy copy/paste into your existing code.

blocks|key|57186|text|GD是绝对必要的吗？ImageMagick更快，生成更好的图像，更具可配置性，最后(IMO)更容易编码。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|57187|entityMap|0|LINK|mutability|MUTABLE|url|http://imagemagick.org/^0|A|B|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Is GD absolutely required? <a href="http://imagemagick.org/" rel="nofollow noreferrer">ImageMagick</a> is faster, generates better images, is more configurable, and finally is (IMO) much easier to code for.

blocks|key|58734|text|我认为this+page是一个很好的起点。它使用imagecreatefrom(jpeg/gif/png)并调整大小并转换图像，然后输出到浏览器。与输出浏览器不同，您可以输出到DB中的BLOB，而无需大量代码重写。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|58735|entityMap|0|LINK|mutability|MUTABLE|url|http://codecaine.co.za/posts/zend-image-class-to-convert-and-resize-images^0|3|9|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I think <a href="http://codecaine.co.za/posts/zend-image-class-to-convert-and-resize-images" rel="nofollow noreferrer">this page</a> is a good starting point. It uses imagecreatefrom(jpeg/gif/png) and resize and converts the image and then outputs to the browser. Instead of outputting the browser you could output to a BLOB in a DB without many minuttes of code-rewrite.

blocks|key|58754|text|如果您想使用gdlib，请使用gdlib+2或更高版本。它有一个名为imagecopyresampled()的函数，该函数将在调整大小的同时对像素进行插值，并且看起来更好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|58755|另外，我经常听到网上有人说，在数据库中存储图像是不好的形式：|58756|58757|它比访问磁盘类型更慢，你的服务器需要运行一个脚本来访问镜像，而不是简单地提供文件|unordered-list-item|58758|你的脚本现在负责web服务器过去处理的许多东西：|58759|设置正确的内容类型标头|58760|<>H19>设置正确的缓存/超时/E-tag标头，以便客户端可以正确缓存镜像。如果不正确执行此操作，影像服务脚本将在每次请求时被命中，从而增加服务器甚至more.|58761|上的负载|58762|​|58763|我能看到的唯一好处是，您不需要保持数据库和映像文件的同步。尽管如此，我还是建议你不要这么做。|58764|entityMap^0|0|0|0|0|1|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|Y|8|@]|9|@]|A|$]]|$1|H|3|I|5|G|7|Z|8|@]|9|@]|A|$]]|$1|J|3|K|5|G|7|10|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|11|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|12|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|13|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|14|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|U|$]]

If you want to use gdlib, use gdlib 2 or higher. It has a function called imagecopyresampled(), which will interpolate pixels while resizing and look much better.

Also, I've always heard noted around the net that storing images in the database is bad form:

<ul>
<li>It's slower to access than the disk</li>
<li>Your server will need to run a script to get to the image instead
of simply serving a file</li>
<li>Your script now is responsible for a lot of stuff the web server used
to handle:

<ul>
<li>Setting the proper Content-Type header</li>
<li>Setting the proper caching/timeout/E-tag headers, so clients can properly cache the image. If do not do this properly, the image serving script will be hit on every request, increasing the load on the server even more.</li>
</ul></li>
</ul>

The only advantage I can see is that you don't need to keep your database and image files synchronized. I would still recommend against it though.

blocks|key|57883|text|您确定服务器上没有ImageMagick吗？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|57884|我邀请您使用PHP+(问题用PHP标记)。我使用的托管公司没有根据phpinfo()打开ImageMagick扩展。|57885|但是当我问他们关于ImageMagick的问题时，他们说这是PHP代码中可用的PHP程序的列表。很简单--+PHP中没有IM接口，但我可以直接从PHP调用IM程序。|57886|我希望你也有同样的选择。|57887|我非常同意--将图像存储在数据库中不是一个好主意。|57888|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|N|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|O|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

Are you sure you have no ImageMagick on server?

I guest you use PHP (question is tagged with PHP). Hosting company which I use has no ImageMagick extension turned on according to phpinfo().

But when I asked them about they said here is the list of ImageMagick programs available from PHP code. So simply -- there are no IM interface in PHP, but I can call IM programs directly from PHP.

I hope you have the same option.

And I strongly agree -- storing images in database is not good idea.

blocks|key|2758529|text|可能是这样的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2758530|<?php
+++//Input+file
+++$file+=+"myImage.png";
+++$img+=+ImageCreateFromPNG($file);

+++//Dimensions
+++$width+=+imagesx($img);
+++$height+=+imagesy($img);
+++$max_width+=+300;
+++$max_height+=+300;
+++$percentage+=+1;

+++//Image+scaling+calculations
+++if+(+$width+>+$max_width+)+{+
++++++$percentage+=+($height+/+($width+/+$max_width))+>+$max_height+?
+++++++++++$height+/+$max_height+:
+++++++++++$width+/+$max_width;
+++}
+++elseif+(+$height+>+$max_height)+{
++++++$percentage+=+($width+/+($height+/+$max_height))+>+$max_width+?+
+++++++++++$width+/+$max_width+:
+++++++++++$height+/+$max_height;
+++}
+++$new_width+=+$width+/+$percentage;
+++$new_height+=+$height+/+$percentage;

+++//scaled+image
+++$out+=+imagecreatetruecolor($new_width,+$new_height);
+++imagecopyresampled($out,+$img,+0,+0,+0,+0,+$new_width,+$new_height,+$width,+$height);

+++//output+image
+++imagepng($out);
?>|code-block|syntax|javascript|2758531|我还没有测试代码，所以可能有一些语法错误，但是它应该给你一个公平的演示，说明它是如何完成的。另外，我还假设了一个PNG文件。您可能需要使用某种switch语句来确定文件类型。|2758532|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Something like this, perhaps: 

<pre><code>
&lt;?php
 //Input file
 $file = "myImage.png";
 $img = ImageCreateFromPNG($file);

 //Dimensions
 $width = imagesx($img);
 $height = imagesy($img);
 $max_width = 300;
 $max_height = 300;
 $percentage = 1;

 //Image scaling calculations
 if ( $width > $max_width ) { 
 $percentage = ($height / ($width / $max_width)) > $max_height ?
 $height / $max_height :
 $width / $max_width;
 }
 elseif ( $height > $max_height) {
 $percentage = ($width / ($height / $max_height)) > $max_width ? 
 $width / $max_width :
 $height / $max_height;
 }
 $new_width = $width / $percentage;
 $new_height = $height / $percentage;

 //scaled image
 $out = imagecreatetruecolor($new_width, $new_height);
 imagecopyresampled($out, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

 //output image
 imagepng($out);
?&gt;
</code></pre>

I haven't tested the code so there might be some syntax errors, however it should give you a fair presentation on how it could be done. Also, I assumed a PNG file. You might want to have some kind of switch statement to determine the file type.

blocks|key|2758534|text|<?php++++++++++++++++++++++++++++++++++++++++++++++
/*
Resizes+an+image+and+converts+it+to+PNG+returning+the+PNG+data+as+a+string
*/
function+imageToPng($srcFile,+$maxSize+=+100)+{++
++++list($width_orig,+$height_orig,+$type)+=+getimagesize($srcFile);++++++++

++++//+Get+the+aspect+ratio
++++$ratio_orig+=+$width_orig+/+$height_orig;

++++$width++=+$maxSize;+
++++$height+=+$maxSize;

++++//+resize+to+height+(orig+is+portrait)+
++++if+($ratio_orig+<+1)+{
++++++++$width+=+$height+*+$ratio_orig;
++++}+
++++//+resize+to+width+(orig+is+landscape)
++++else+{
++++++++$height+=+$width+/+$ratio_orig;
++++}

++++//+Temporarily+increase+the+memory+limit+to+allow+for+larger+images
++++ini_set('memory_limit',+'32M');+

++++switch+($type)+
++++{
++++++++case+IMAGETYPE_GIF:+
++++++++++++$image+=+imagecreatefromgif($srcFile);+
++++++++++++break;+++
++++++++case+IMAGETYPE_JPEG:++
++++++++++++$image+=+imagecreatefromjpeg($srcFile);+
++++++++++++break;+++
++++++++case+IMAGETYPE_PNG:++
++++++++++++$image+=+imagecreatefrompng($srcFile);
++++++++++++break;+
++++++++default:
++++++++++++throw+new+Exception('Unrecognized+image+type+'+.+$type);
++++}

++++//+create+a+new+blank+image
++++$newImage+=+imagecreatetruecolor($width,+$height);

++++//+Copy+the+old+image+to+the+new+image
++++imagecopyresampled($newImage,+$image,+0,+0,+0,+0,+$width,+$height,+$width_orig,+$height_orig);

++++//+Output+to+a+temp+file
++++$destFile+=+tempnam();
++++imagepng($newImage,+$destFile);++

++++//+Free+memory+++++++++++++++++++++++++++
++++imagedestroy($newImage);

++++if+(+is_file($destFile)+)+{
++++++++$f+=+fopen($destFile,+'rb');+++
++++++++$data+=+fread($f);+++++++
++++++++fclose($f);

++++++++//+Remove+the+tempfile
++++++++unlink($destFile);++++
++++++++return+$data;
++++}

++++throw+new+Exception('Image+conversion+failed.');
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2758535|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&lt;?php 
/*
Resizes an image and converts it to PNG returning the PNG data as a string
*/
function imageToPng($srcFile, $maxSize = 100) { 
 list($width_orig, $height_orig, $type) = getimagesize($srcFile); 

 // Get the aspect ratio
 $ratio_orig = $width_orig / $height_orig;

 $width = $maxSize; 
 $height = $maxSize;

 // resize to height (orig is portrait) 
 if ($ratio_orig &lt; 1) {
 $width = $height * $ratio_orig;
 } 
 // resize to width (orig is landscape)
 else {
 $height = $width / $ratio_orig;
 }

 // Temporarily increase the memory limit to allow for larger images
 ini_set('memory_limit', '32M'); 

 switch ($type) 
 {
 case IMAGETYPE_GIF: 
 $image = imagecreatefromgif($srcFile); 
 break; 
 case IMAGETYPE_JPEG: 
 $image = imagecreatefromjpeg($srcFile); 
 break; 
 case IMAGETYPE_PNG: 
 $image = imagecreatefrompng($srcFile);
 break; 
 default:
 throw new Exception('Unrecognized image type ' . $type);
 }

 // create a new blank image
 $newImage = imagecreatetruecolor($width, $height);

 // Copy the old image to the new image
 imagecopyresampled($newImage, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig);

 // Output to a temp file
 $destFile = tempnam();
 imagepng($newImage, $destFile); 

 // Free memory 
 imagedestroy($newImage);

 if ( is_file($destFile) ) {
 $f = fopen($destFile, 'rb'); 
 $data = fread($f); 
 fclose($f);

 // Remove the tempfile
 unlink($destFile); 
 return $data;
 }

 throw new Exception('Image conversion failed.');
}
</code></pre>

blocks|key|2546557|text|phpThumb是一个高级抽象，可能值得一看。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2546558|entityMap|0|LINK|mutability|MUTABLE|url|http://phpthumb.sourceforge.net/^0|0|8|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

<a href="http://phpthumb.sourceforge.net/" rel="nofollow noreferrer">phpThumb</a> is a high-level abstraction that may be worth looking at.

I want to allow users to upload avatar-type images in a variety of formats (GIF, JPEG, and PNG at least), but to save them all as PNG database BLOBs. If the images are oversized, pixelwise, I want to resize them before DB-insertion.

What is the best way to use GD to do the resizing and PNG conversion?

Edit: Sadly, only <a href="http://php.net/manual/en/book.image.php" rel="nofollow noreferrer">GD</a> is available on the server I need to use, no <a href="http://www.imagemagick.org/script/index.php" rel="nofollow noreferrer">ImageMagick</a>.

How do I resize and convert an uploaded image to a PNG using GD?

数据库

服务器

我想让用户上传化身类型的图像在各种格式(的GIF，JPEG，和PNG至少)，但将它们保存为PNG数据库斑点。如果图像过大，像素，我想在DB插入之前调整它们的大小。使用GD进行大小调整和PNG转换的最佳方式是什么？编辑:遗憾的是，在我需要使用的服务器上只有可用，没有。

问如何使用GD调整上传图像的大小并将其转换为PNG？
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