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Crop to selected area feature when exporting

kajsadakajsada Global Mapper UserPosts: 13
edited March 2011 in Technical Support
I have a GEO tiff which I would like to export to ECW-format and in the export crop the image to a selected area feature. This all works fine, but when importing the new file to GM and setting the background color to transparent I get a collar of pixels around the image that have a slightly different RGB-value and which doesn't turn transparent. I can solve this by checking the alternative 'make similar colors transparent as well' but I would like to use the image in Microstation the same way and in mstn I don't have that option.
Is there a way to get the same RGB-value in all of the background when exporting the file?

Thanks in advance!


  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2011
    The problem is that ECW uses lossy compression, so your colors won't exactly match what they were in Global Mapper when you export. If you check the option to mark background pixels as transparent when exporting the ECW file you should also get an alpha channel marking the background pixels as transparent regardless of color, but many applications won't make use of this. In general it is more difficult to get transparency that works in any application when using lossy formats like ECW.

    Let me know if I can be of further assistance.


    Global Mapper Support
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