Optimize uploaded images with php (jpeg)

The imagejpeg function is where you assign the quality. If you're already setting that to an appropriate value then there is little else you can do.

Page speed probably considers all images above a certain size to be "needing compression", perhaps just ensure they are all as small as reasonable (in terms of height/width) and compressed.

You can find more about page speed and it's compression suggestions on the pagespeed docs http://code.google.com/speed/page-speed/docs/payload.html#CompressImages which describes some of the techniques/tools to compress appropriately.

I've also just read the following:

Several tools are available that perform further, lossless compression on JPEG and PNG files, with no effect on image quality. For JPEG, we recommend jpegtran or jpegoptim (available on Linux only; run with the --strip-all option). For PNG, we recommend OptiPNG or PNGOUT.

So perhaps (if you really want to stick to Google's suggestions) you could use PHP's exec to run one of those tools on files as they are uploaded.

To compress with php you do the following (sounds like you are already doing this):

Where $source_url is the image, $destination_url is where to save and $quality is a number between 1 and 100 choosing how much jpeg compression to use.

function compressImage($source_url, $destination_url, $quality) {    $info = getimagesize($source_url);    if ($info['mime'] == 'image/jpeg') $image = imagecreatefromjpeg($source_url);    elseif ($info['mime'] == 'image/gif') $image = imagecreatefromgif($source_url);    elseif ($info['mime'] == 'image/png') $image = imagecreatefrompng($source_url);    //save file    imagejpeg($image, $destination_url, $quality);    //return destination file    return $destination_url;}

Repaired function:

function compressImage($source_url, $destination_url, $quality) {    //$quality :: 0 - 100    if( $destination_url == NULL || $destination_url == "" ) $destination_url = $source_url;    $info = getimagesize($source_url);    if ($info['mime'] == 'image/jpeg' || $info['mime'] == 'image/jpg')    {        $image = imagecreatefromjpeg($source_url);        //save file        //ranges from 0 (worst quality, smaller file) to 100 (best quality, biggest file). The default is the default IJG quality value (about 75).        imagejpeg($image, $destination_url, $quality);        //Free up memory        imagedestroy($image);    }    elseif ($info['mime'] == 'image/png')    {        $image = imagecreatefrompng($source_url);        imageAlphaBlending($image, true);        imageSaveAlpha($image, true);        /* chang to png quality */        $png_quality = 9 - round(($quality / 100 ) * 9 );        imagePng($image, $destination_url, $png_quality);//Compression level: from 0 (no compression) to 9(full compression).        //Free up memory        imagedestroy($image);    }else        return FALSE;    return $destination_url;}

You could use Imagick class for this. Consider following wrapper function:

<?php    function resizeImage($imagePath, $width, $height, $blur, $filterType = Imagick::FILTER_LANCZOS, $bestFit = false)    {        //The blur factor where > 1 is blurry, < 1 is sharp.        $img= new \Imagick(realpath($imagePath));        $img->setCompression(Imagick::COMPRESSION_JPEG);         $img->setCompressionQuality(40);        $img->stripImage();        $img->resizeImage($width, $height, $filterType, $blur, $bestFit);        $img->writeImage();    }?>

Read more on how to resize images with Imagick at:
http://php.net/manual/en/class.imagick.php
http://php.net/manual/en/imagick.resizeimage.phphttp://php.net/manual/en/imagick.constants.php#imagick.constants.filters