Imagemagick & php prevent text output while using convert

Hi: I am using these commands to compare colors, it works however it prints text that I do not want to be printed:

$color2= system("/usr/bin/convert xc:'#".$color2."' -format '%[pixel:s]' info:");
$result= system("/usr/bin/convert xc:'".$color."' -alpha set -channel RGBA -fuzz ".$fuzz." -fill '".$color2."' -opaque '".$color2."' -format '%[pixel:s]' info:");

outputs:

 red grey20 rgb(238,0,0) grey20 rgb(221,0,0) grey20 rgb(204,0,0) grey20 rgb(187,0,0) grey20 rgb(170,0,0) grey20 rgb(153,0,0) grey20 rgb(136,0,0) grey20 rgb(119,0,0) grey20 rgb(102,0,0) grey20 rgb(85,0,0) grey20 rgb(68,0,0) grey20 rgb(51,0,0) grey20 rgb(204,51,51) grey20 rgb(153,51,51) grey20 rgb(204,102,102) grey20 rgb(204,0,51) grey20 lime grey20 rgb(0,238,0) grey20 rgb(0,221,0) grey20 rgb(0,204,0) grey20 rgb(0,187,0) grey20 rgb(0,170,0) grey20 rgb(0,153,0) grey20 rgb(0,136,0) grey20 rgb(0,119,0) grey20 rgb(0,102,0) grey20 rgb(0,85,0) grey20 rgb(0,68,0) grey20 rgb(0,51,0) grey20 blue grey20 rgb(0,0,238) grey20 rgb(0,0,221) grey20 rgb(0,0,204) grey20 rgb(0,0,187) grey20 rgb(0,0,170) grey20 rgb(0,0,153) grey20 rgb(0,0,136) grey20 rgb(0,0,119) grey20 rgb(0,0,102) grey20 rgb(0,0,85) grey20 rgb(0,0,68) grey20 rgb(0,0,51) grey20 rgb(0,127,255) grey20 rgb(51,51,102) grey开发者_C百科20 cyan grey20 rgb(153,204,255) grey20 rgb(127,0,255) grey20 rgb(102,45,145) grey20 rgb(255,0,127) grey20 rgb(244,154,193) grey20 yellow grey20 rgb(255,127,0) grey20 rgb(247,148,29) grey20 rgb(96,58,32) grey20 rgb(117,76,36) grey20 black grey20 grey20 grey20

How do I prevent that text from being dispalyed?

http://php.net/manual/de/function.system.php -> set the return var value, so the output is placed there instead of printed out