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What is metadata?

When acquiring images in microscopy, the image files that are stored contain two main things:

  1. image data: which is essentially ‘pixel values’
  2. metadata: information on the image data including pixel size, bit depth, dimension and objective information, etc.

Metadata is essential to correctly read image data; for example, to have accurate measurements, the image needs to be calibrated according to the correct/associated pixel size. Saving and preserving metadata is key in quantitative image analysis.

How do I open/read my metadata?

To start, try a high level API approach via a GUI…

Using a GUI

If importing your images via Bio-Formats Importer (which we suggest you do), you can either:

  • In Stack Viewing, View stack with: “Metadata only”


  • In Metadata viewing: check “Display Metadata” or “Display OME-XML metadata”

OMEVisual is another tool that can visualize OME metadata; it is a Fiji plugin.

These tools allow you to quickly check if your metadata ‘looks’ correct… are there the correct number of image blocks (i.e. one per tile if multi-scan image)? Are the dimensions correct? etc.

What if I cannot read my metadata via a GUI?!

Did you observe a problem with your metadata via a GUI? Was there no data at all? Or was metadata missing? If this is the case, then perhaps there are structural issues with your metadata that require a bit more in-depth inspection via command line tools.

Using the Command Line

Bio-Formats has a whole host of information regarding extracting, processing, and validating OME-XML. So check out their resources for more detailed information.

In brief, there are command line tools available via Bio-Formats to properly inspect and validate the XML in an OME-TIFF file.

Both the tiffcomment and xmlvalid commands are used; tiffcomment extracts the XML from the file and xmlvalid validates the XML and prints any errors to the console. See this page for more details.