Thanks to all for the help. I have transparent images now. Thanks, Scott Weldon, M.A. Supervisor, Medical Illustrator Division of Cardiothoracic Surgery Michael E. DeBakey Department of Surgery Baylor College of Medicine One Baylor Plaza, BCM 390 Houston, TX 77030 TEL: (832) 355-9941 FAX: (832) 355-9948 E-mail: sweldon@bcm.edu -----Original Message----- From: Thomas Goddard [mailto:goddard@cgl.ucsf.edu] Sent: Tuesday, March 28, 2006 11:43 AM To: Weldon, Scott Cc: chimera-users@cgl.ucsf.edu Subject: Re: [Chimera-users] Question about background transparency Hi Scott, You need 2 dashes in the background opacity option --bgopacity According to the Chimera manual that option should occur before input PDB files in the Chimera startup command. Here are the relevant pages of the Chimera User's Guide: http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/startup.html http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/options.html Tom