Determining pixel depth?

timhoman
timhoman Global Mapper UserTrusted User
edited March 2008 in Raster Data
Hi. I'm fairly new to Global Mapper.
Is it possible to determine the pixel depth of raster images with GM?

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  • global_mapper
    global_mapper Administrator
    edited March 2008
    For most raster formats, simply open the Overlay Control Center, select the layer, then press the Metadata button to list information about the image, including in some cases the bit depth.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • timhoman
    timhoman Global Mapper User Trusted User
    edited March 2008
    Apparently I am not using "most raster formats".
    I am using MrSid and NITF - Overlay Control Center does not indicate pixel depth for either.
    Thanks.
  • global_mapper
    global_mapper Administrator
    edited March 2008
    I have added support for displaying the BIT_DEPTH value for MrSID and NITF imagery in the metadata dialog. I have placed a new build at http://www.globalmapper.com/global_mapper9.zip with the change for you to try. Simply download that file and extract the contents into your existing v9.xx installation folder to give it a try.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • timhoman
    timhoman Global Mapper User Trusted User
    edited March 2008
    I have tried the new GM support for displaying the BIT_DEPTH value for MrSID and NITF imagery in the metadata dialog. GM reports my MrSID files as NUM_BANDS = 3, and BIT_DEPTH = 24. GM is also reporting my NITF files as NUM_BANDS = 4, and BIT_DEPTH = 64.

    I'm not sure how GM calculates the BIT_DEPTH but... ArcCatalog 9.2 and Google Earth Fusion 3.0.2 recognize the same MrSiD files as having Number of Bands = 3, and Pixel Depth = 8 Bit. The NITF files are reported as Number of Bands = 4, and Pixel Depth = 16 Bit.

    Perhaps GM could just display the pixel depth PER band. Thanks.

    I really appreciate the initial effort to address my request for displaying pixel depth -
    Using the info allows me to determine when a file needs to be exported to an 8-bit format for use in GE Fusion.

    Thanks.
  • global_mapper
    global_mapper Administrator
    edited March 2008
    Global Mapper is reporting the total number of bits used for an entire sample as the BIT_DEPTH value. It sounds like ArcCatalog and Google Earth and reporting the number of bits in a single color channel. To get the value that ArcCatalog is reporting, just take the BIT_DEPTH value reported by Global Mapper and divide it by the NUM_BANDS value.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • timhoman
    timhoman Global Mapper User Trusted User
    edited March 2008
    I understand the BIT_DEPTH/NUM_BANDS relationship and I greatly appreciate the addition of the info to the metadata - perhaps at some point GM could display both Image and Band bit-depth... if for no other reason than to eliminate that functioning part of the human brain needed for division.

    You forgot to mention that the Band Setup tab is now available in for MrSID and NITF - THANKS!

    Thanks again - now for more GM butt-kicking adventures.

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