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Metadata

    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”

    OR

    • 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.