Codeigniter image resize?

You shouldn't load image_lib in foreach. Try to use code below

$this->load->library('image_lib');
foreach($results as $row) {
    $config['image_library'] = 'gd2';
    $config['source_image'] = '/img/proizvodi/'.$row->proizvodid.'.jpg';
    $config['create_thumb'] = TRUE;
    $config['maintain_ratio'] = TRUE;
    $config['width']     = 75;
    $config['height']   = 50;

    $this->image_lib->clear();
    $this->image_lib->initialize($config);
    $this->image_lib->resize();
}

If it wont work - check the upload folder permissions.