JPEG image quality

Hi,

I use Watermark Reloaded Pro on a photographer web site : http://www.eric-pioche-photographe.com.

The JPEG image quality looks to be altered by the Watermark Reloaded plugin (less color information).

Could you please tell me if JPEG images are modified or re-compressed by the plugin ?

Thanks in advance for your support.

http://ww.wp.xz.cn/extend/plugins/watermark-reloaded/