How to Create Thumbnails from Image using PHP



First Step: Install GD

Image processing in PHP can be done powerfully with a library, GD. GD image library needs to be installed and activated on your PHP to be able to do image processing.

To check if GD is installed, check your phpinfo:

Open a file phptest.php (that contains following code) in your browser:

<?php
phpinfo()
?>

If you find GD in the output of the browser, this means GD is installed on your server.

If GD is not installed, install it.

Second Step: Start Coding in PHP for Thumbnail generation

The code below creates a function named createThumbNail that will get three parameters: path to the directory that contains images, second to the directory where thumbnails would be places and 3rd parameter is the width of the thumbnail images.


<?php
function createThumbNail($pathToImages, $pathToThumbs, $thumbWidth )
{
  // open the directory
  $dir = opendir( $pathToImages );

  // loop through it, looking for any/all JPG files:
  while (false !== ($fname = readdir( $dir ))) {
    // parse path for the extension
    $info = pathinfo($pathToImages . $fname);
    // continue only if this is a JPEG image
    if ( strtolower($info['extension']) == 'jpg' )
    {
      echo "Creating thumbnail for {$fname} <br />";

      // load image and get image size
      $img = imagecreatefromjpeg( "{$pathToImages}{$fname}" );
      $width = imagesx( $img );
      $height = imagesy( $img );

      // calculate thumbnail size
      $new_width = $thumbWidth;
      $new_height = floor( $height * ( $thumbWidth / $width ) );

      // create a new temporary image
      $tmp_img = imagecreatetruecolor( $new_width, $new_height );

      // copy and resize old image into new image
      imagecopyresized( $tmp_img, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height );

      // save thumbnail into a file
      imagejpeg( $tmp_img, "{$pathToThumbs}{$fname}" );
    }
  }
  // close the directory
  closedir( $dir );
}

?>

Now, you can call the function in the same php file to genearte thumbnails:

<?php

// files is the folder containing images, files/thumbnails/ is the folder in which thumbnails would be created and 50 is the width of the thumbnail.
createThumbNail("files/","files/thumbnails/",50);
?>

Note, we have used following PHP Gd functions for image thumbnail generation in createThumbNail():

* imageCreateFromJPEG() to create a copy to work on of a .jpg image.
* imageCreateFromPNG() to create a copy to work on of a .png image.
* imageSX() to get the width of the original image.
* imageSY() to get the height of the original image.
* ImageCreateTrueColor() to create a new truecolour image object.
* imageCopyResampled() to resample the image.





nice post for beginner

Googd tutorial for php newbies.

very nice function clean,
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