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 can read 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.Voltage = 300000.0 - Accelerating voltage
------------------------ 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