[3dem] dm3 vs dm4 format?

[Ludtke, Steven J.]

The DMx formats are proprietary Gatan formats, and they have a fairly complicated internal structure. We got enough information  to write readers for both formats in EMAN2, but we are not able to properly read all possible header metadata. If memory serves, the primary difference between DM3 and DM4 is whether the internal pointers are 32 or 64 bit ints, but I may be misremembering.

Someone from Gatan is welcome to post and contradict any of these statements :^)

--------------------------------------------------------------------------------------
Steven Ludtke, Ph.D. <sludtke at bcm.edu<mailto:sludtke at bcm.edu>>                      Baylor College of Medicine
Charles C. Bell Jr., Professor of Structural Biology
Dept. of Biochemistry and Molecular Biology                      (www.bcm.edu/biochem<http://www.bcm.edu/biochem>)
Academic Director, CryoEM Core                                        (cryoem.bcm.edu<http://cryoem.bcm.edu>)
Co-Director CIBR Center                                    (www.bcm.edu/research/cibr<http://www.bcm.edu/research/cibr>)



On Apr 16, 2019, at 11:13 AM, Morgan, David Gene <dagmorga at indiana.edu<mailto:dagmorga at indiana.edu>> wrote:

Hi,

   One of our microscopes has a Gatan OneView camera.  Users keep switching back and forth between saving images in dm3 or dm4 format.  I would prefer to use one or the other, but I don't really know whether it matters which.  I know that the dm4 format metadata can easily deal with exposure times, number of frames, etc. and so I suspect it is a "better" format for this camera.  But that info may also be hidden in the dm3 metadata also, and if so, I'm sure I can parse it out.  Does anyone have comments or preferences?  Thanks.

--
   politics is more difficult than physics.
                                            A. Einstein

           David Gene Morgan
       Electron Microscopy Center
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            IU Bloomington
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