Re: How to set/remove the Exif Image Width/Height/Thumbnail attributes?

On Wed, 24 Jul 2013, hack bear wrote:

> Hi,
> 
> I have patched GM to write out the updated attribute. It works for EXIF:Orientation tag but cannot
> alter or remove the Exif Image Width/Height or Thumbnail tags. I tried several variants of the tag
> names like 'EXIF:Exif Image Width', 'Exif Image Width', etc.; none works.
> 
> Why doesn't -set work for those attributes? And also how to remove an attribute?

GraphicsMagick does not currently include support for editing EXIF 
tags.  Regardless, the documentation says that these tag names are 
ImageWidth, ImageLength, and in the code I see ThumbnailRawBytes which 
must be the thumbnail.  There is also ExifImageWidth and 
ExifImageLength which I see used in an image here.  It may be that 
ExifImageWidth and ExifImageLength are the correct ones to use since 
the others are standard TIFF file IFD tags.

I do see that GraphicsMagick dumps the tags with a space before each 
capital letter, but that is not how the tag names are stored or 
searched for.

Unless your patch also includes a patch for updating the 
EXIF:Orientation tag then it is likely that the orientation is coming 
from the file header rather than EXIF.  If you have a working patch 
like this, then we would be happy to receive it.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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