php使用Image Magick将PDF文件转换为JPG文件的方法

$pdf_file  = './pdf/demo.pdf';
$save_to  = './jpg/demo.jpg';
//make sure that apache has permissions to write in this folder! 
//(common problem)
 
//execute imagemagick command 'convert' and convert pdf
//to jpg with applied settings
exec('convert "'.$pdf_file.'" -colorspace rgb -resize 800 "'.$save_to.'"', $output, $return_var);
 
if($return_var == 0) {
//if exec successfuly converted pdf to jpg
  print "conversion ok";
}
else print "conversion failed.".$output;