For Chimera bugs, please use Chimera's Help / Report a Bug dialog. That will tell us more about your computer that will let us see if the bug is related to your setup. Specially, it tells us the version of Chimera, which operating system is being used, the graphics card, and the graphics driver version. That said, I haven't seen this bug for many years. So if you're not using a current version of Chimera, it's time to update. The other common fix is to update your graphics driver (or install one, if you haven't already). HTH, Greg March 25 2015 3:47 AM, "sunyeping" wrote: Dear all,I find in the saved volume image (png file), there are some black bar whick mask the image? Please see the following link:https://www.dropbox.com/s/nvy3douvafymqxd/image.png?dl=0 (https://www.dropbox.com/s/nvy3douvafymqxd/image.png?dl=0)Do you know how to get rid of them?Thank you very much! Yeping Sun Institute of Microbiology, Chinese Academy of Sciences