Hi Salim,

  The Chimera MRC file writer puts the minimum, maximum and mean value of exactly the grid values that are being written to the MRC file.  So for instance if you are writing out a subvolume of a bigger map, the min, max, mean are not the values for the bigger map, they are the values for the subvolume.  Likewise if you write a subsampled map where only every other data value is included along each axis, then only those values are included in the min, max, mean.

  Here is the Chimera code that writes MRC:

http://plato.cgl.ucsf.edu/trac/chimera/browser/trunk/libs/VolumeData/mrc/writemrc.py

  Tom

On Apr 13, 2017, at 11:59 AM, SALIM SAZZED  wrote:

Hello,
I am a Ph.D. student of Computer Science department at Old Dominion University, USA. I am using Chimera for my research. Can you please tell me how Chimera calculates DMIN, DMAX, DMEAN value of MRC header after chopping a portion of original MRC/MAP?

My understanding about that-


DMIN: The minimum density value of the voxels in the MRC/MAP Cube.

DMAX: The maximum density value of the voxels in the MRC/MAP Cube.

DMEAN: The average density of voxels (add all the voxels density value and divide it by the number of voxels).


It will be really helpful if you clarify.


Thanks
Salim Sazzed 



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