Reducing image size on digital photos

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Reducing image size on digital photos - PHP

Archive - Originally posted on "The Horse's Mouth" - 2010-01-17 10:01:15 - Graham Ellis

Working on the image library, I'm wanting to have all my resources / pictures available via a web site ... but I really don't want to hold them at full resolution - for our needs, 800 x 600 is quite big enough and the storage and bandwidth when I call up lots of pictures would be something of an issue.

Using PHP and the GD library, I'm copying and resizing images that would be over a quarter of a megabyte to download, using the following code, which you'll note maintains the aspect ratio, and limits the image to a maximum of 800 pixels wide, and 600 pixels tall.

if (filesize($fx) > 256000) {

  $in_img = imagecreatefromjpeg($fx);

  $width = $in_width = imagesx( $in_img );

  $height = $in_height = imagesy( $in_img );

  if ($width > 800) {

    $height = $height * 800 / $width;

    $width = 800;

    }

  if ($height > 600) {

    $width = $width * 600 / $height;

    $height = 600;

    }

  $img = imagecreatetruecolor( $width, $height );

  imagecopyresized( $img, $in_img, 0, 0, 0, 0, $width, $height, $in_width, $in_height );

  imagejpeg($img, "thumbs/$fx" );

  $instr = fopen("thumbs/$fx","rb");

  $imagebytes = fread($instr,filesize("thumbs/$fx"));

} else {

  $instr = fopen($fx,"rb");

  $imagebytes = fread($instr,filesize($fx));

}

I have used a temporary directory for my reduced size picture (they're not really small enough to be called thumbnails), and the $imagebytes variable gets sent out later in the PHP script as the response to the http request for the image. We're also (a story I have told elsewhere) saving the image into a database.

Some more images in the new library ...