I'm a light but long time user, and enthusiastic advocate of HoudahGeo. 

I want to write out signed, decimal degrees (-34.919, 138.613) rather than direction, degrees, minutes and seconds to my image file's EXIF metadata. If I look at the GPS data in a number of graphic programs of images that that I have processed with HoudahGeo I see DMS not decimals. What format does HoudahGeo write and is it changeable?

Thanks, Ainsley
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Hi Ainsley,

The native format for latitude and longitude in EXIF:GPS tags uses decimal degrees. Direction is stored separately.
The native format for latitude and longitude in XMP tags stores integer degrees, decimal minutes and direction.
HoudahGeo writes both EXIF and XMP where possible.

Do you get a different display in your graphics application depending on whether or not the image was modified by HoudahGeo?

How the values are displayed is left up to the application displaying it. I wonder if some applications might prefer XMP over EXIF or vice-versa and proceed to display the values in a format close to the native one for that tag.

Pierre Bernard
Houdah Software s.à r.l.
Houdah Software s. à r. l.

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Thanks Pierre. I did have a growing suspicion that is was how the coordinates were being displayed rather than how they were recorded.
So rather than using an other app with EXIF-read capabilities I just issued an:
exiftool filename.jpg
command and yes, DMS & direction were returned (so that is apparently default for reading, but says nothing about storage), while:
exiftool -c FMT -n filename.jpg
gave signed decimal coordinates (but also changed numerous other data like Color Space from "sRGB" to "1").
I have no need for it now, but in the future will need to work out how to extract full resolution, decimal coordinates from my image files. Knowing they are being written and stored correctly by HoudahGeo for now is enough.
Thank you.

--- oh! exiftool -c "%+.10f" appears to do what I want. I'll be all set. Thanks again. A.
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