Finding Image Parameters in Digital Micrograph DM3 Files

The DM3 file format is the gold standard for saving Digital Micrograph files. The metadata in the image stores microscope and image information that is lost if the image is stored in any other file format. Some of this information includes the microscope magnification and the pixel size which are necessary for measuring the size of objects in the micrograph.

This metadata is available in the Digital Micrograph program by going to Object/Image Display and clicking on Image Info and Image Tags.

The free program ImageJ with a reader plugin also can handle the DM3 file format. Check here for more information on file saving. To view the tag information in ImageJ click on Image/Show Info.. Examples of some of the more useful tags are described below.

root.ImageList.1.ImageTags.DataBar.Acquisition Date = 5/12/2006 - Date the image was taken

root.ImageList.1.ImageTags.DataBar.Acquisition Time = 11:43:27 AM - Time the image was taken

root.ImageList.1.ImageTags.Microscope Info.Cs(mm) = 2.3 - Spherical aberration constant

root.ImageList.1.ImageTags.Microscope Info.Indicated Magnification = 39000.0 - Nominal microscope magnification

root.ImageList.1.ImageTags.Microscope Info.Voltage = 300000.0 - Accelerating voltage

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Title: EM-micrograph.dm3 - Saved file name
Width: 618.32 nm (2048) - Width of image in nm, Number of pixels in X direction
Height: 618.32 nm (2048) - Height of image in nm, Number of pixels in Y direction
Resolution: 3.312 pixels per nm - Size of the pixel at the microscope magnification, In this example ~0.3 nm/pixel
Bits per pixel: 32 (float) - Bit depth of the image