compress image file size on upload??

Question

I am uploading product screenshots to my website... I want to upload the original image as it is and also create a thumbnail for it, but after uploading both the files the filesize of the thumbnail created is a bit larger than expected. Is there any way I could reduce the filesize of the thumbnail without compromising much on the quality in php or by using Imagemagick( which I have no idea how to use but I'm willing to learn if needed)...
Below is the code I'm using to upload my files..

<form action="<?php echo $_server['php-self'];  ?>" method="post" enctype="multipart/form-data" id="something" class="uniForm">
    <input name="new_image" id="new_image" size="30" type="file" class="fileUpload" />
    <button name="submit" type="submit" class="submitButton">Upload/Resize Image</button>

<?php
    if(isset($_POST['submit'])){
      if (isset ($_FILES['new_image'])){
          $imagename = $_FILES['new_image']['name'];
          $source = $_FILES['new_image']['tmp_name'];
          $target = "images/".$imagename;
          move_uploaded_file($source, $target);

          $imagepath = $imagename;
          $save = "images/" . $imagepath; //This is the new file you saving
          $file = "images/" . $imagepath; //This is the original file

          list($width, $height) = getimagesize($file) ; 


          $tn = imagecreatetruecolor($width, $height) ; 
          $image = imagecreatefromjpeg($file) ; 
          imagecopyresampled($tn, $image, 0, 0, 0, 0, $width, $height, $width, $height) ; 

          imagejpeg($tn, $save, 100) ; 

          $save = "images/sml_" . $imagepath; //This is the new file you saving
          $file = "images/" . $imagepath; //This is the original file

          list($width, $height) = getimagesize($file) ; 

          $modwidth = 130; 

          $diff = $width / $modwidth;

          $modheight = 185; 
          $tn = imagecreatetruecolor($modwidth, $modheight) ; 
          $image = imagecreatefromjpeg($file) ; 
          imagecopyresampled($tn, $image, 0, 0, 0, 0, $modwidth, $modheight, $width, $height) ; 

          imagejpeg($tn, $save, 100) ; 
        echo "Large image: <img src='images/".$imagepath."'><br>"; 
        echo "Thumbnail: <img src='images/sml_".$imagepath."'>"; 

      }
    } ?>

Kindly point me in the right direction...Thanks

Answer 1

A quality setting of 100% ist quite to large. try 85 or 90% you wont see a difference on most of the images.

see: http://www.ampsoft.net/webdesign-l/jpeg-compression.html

Answer 2

Don't pass 100 as the quality for imagejpeg() - anything over 90 is generally overkill and just gets you a bigger JPEG. For a thumbnail, try 75 and work downwards until the quality/size tradeoff is acceptable.

//try this
imagejpeg($tn, $save, 75) ;

Answer 3

75 is the default quality setting, however you'll notice quality decrease considerably if you use it. 90 gives you a great image quality and reduces the file size in half, if you want to decrease the file size even more use 85 or 80 but nothing bellow that.

Answer 4

If using jpeg, using a quality between 75 and 85 is generally more than acceptable (and 100 takes way too much space, for a gain that is not that important, btw), at least for photos.

As a sidenote, if you are dealing with screenshots, using PNG might get you a better quality : jpeg degrades the images (it is quite OK for photos, but for screenshots, with fonts that are drawn by pixels, it can bring some not nice-looking effect)