找到: LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
  LogFormat "%h %l %u %t \"%r\" %>s %b" common
  LogFormat "%{Referer}i -> %U" referer
  LogFormat "%{User-agent}i" agent
  再后面加上图片文件的类型(添加到虚拟主机配置文件中) 
<VirtualHost *:80>
SetEnvIf Request_URI \.gif$ gif-image
  SetEnvIf Request_URI \.GIF$ gif-image
  SetEnvIf Request_URI \.jpg$ gif-image
  SetEnvIf Request_URI \.JPG$ gif-image
  SetEnvIf Request_URI \.png$ gif-image
  SetEnvIf Request_URI \.js$ gif-image
  SetEnvIf Request_URI \.bmp$ gif-image
  SetEnvIf Request_URI \.css$ gif-image
  SetEnvIf Request_URI \.mid$ gif-image
  SetEnvIf Request_URI \.swf$ gif-image
  SetEnvIf Request_URI \.mmf$ gif-image
  SetEnvIf Request_URI \.wma$ gif-image
  SetEnvIf Request_URI \.midi$ gif-image
  记日志时
  CustomLog /usr/local/apache/logs/access.log combined env=!gif-image 
</VirtualHost>
原文:http://www.cnblogs.com/the-study-of-linux/p/5222627.html