아래와 같이 사용이 가능합니다.

https://images1-focus-opensocial.googleusercontent.com/gadgets/proxy?container=focus&url=http://coinbbs.co/data/editor/1812/0d5526b28e5721db41cf421fc959a833_1544716702_7462.jpg

[원본]

https://images1-focus-opensocial.googleusercontent.com/gadgets/proxy?container=focus&resize_w=250&url=http://coinbbs.co/data/editor/1812/0d5526b28e5721db41cf421fc959a833_1544716702_7462.jpg
 

[리사이즈]

자신의 이미지가 http://coinbbs.co/data/editor/1812/0d5526b28e5721db41cf421fc959a833_1544716702_7462.jpg 일경우 앞에 https://images1-focus-opensocial.googleusercontent.com/gadgets/proxy?container=focus&url= 만 넣어주시면 됩니다.
 

저같은 경우에는 /data/dbconfig.php 파일에
define('CDN_IMAGE_URL', 'https://images1-focus-opensocial.googleusercontent.com/gadgets/proxy?container=focus&url=');

/lib/thumbnail.lib.php 에
$thumb_tag = '<img'.$itemprop.' src="'.CDN_IMAGE_URL.$src.'" alt="'.$alt.'" class="img-tag '.$class.'"'.$img_attr.'/>';
$thumb_tag = '<img'.$itemprop.' src="'.CDN_IMAGE_URL.G5_URL.str_replace($filename, $thumb_file, $data_path).'" alt="'.$alt.'" class="img-tag '.$class.'"'.$img_attr.'/>';

위와 같은 형태로 넣어주었습니다. 그외 이미지 사용하는 곳에도요.

아래는 사용가능한 구글 도메인 정보입니다.

173.194.72.132 images1-focus-opensocial.googleusercontent.com
74.125.31.132 images2-focus-opensocial.googleusercontent.com
74.125.31.132 images3-focus-opensocial.googleusercontent.com
173.194.72.132 images4-focus-opensocial.googleusercontent.com
74.125.31.132 images5-focus-opensocial.googleusercontent.com
74.125.31.132 images6-focus-opensocial.googleusercontent.com
74.125.31.132 images7-focus-opensocial.googleusercontent.com
173.194.72.132 images8-focus-opensocial.googleusercontent.com
173.194.72.132 images9-focus-opensocial.googleusercontent.com