Ok, I have a simple PHP script, that generates a thumbnail for a large picture using Imagick PHP extension.
The simplified script is:
$this->image = new Imagick ();
$this->image->readImage($origFileName);
$this->image->resizeImage(76, 50, Imagick::FILTER_CATROM, $this->blur);
$this->image->contrastImage( 1 );
$this->image->sharpenimage( 0.8, 0.6);
$this->image->setImageCompression(imagick::COMPRESSION_JPEG);
$this->image->setImageCompressionQuality(1); // REALLY strong JPEG compression
The resulting image is quite ugly (of course it is!): http://dl.dropbox.com/u/16514036/thumbnail.php.jpg
But look at the size - it is 28 KB! Crap, what?!
As far as I understand the problem is in metadata or embed preview from Photoshop.
So the question is - how can I optimize thumbnail and remove all obsolete data from it?
Meta data can be cleaned by http://php.net/manual/en/function.imagick-stripimage.php