#37 Option to prevent addition of Exif Software tag

[Jean-Louis Grall]

When processing images, GraphicsMagick adds a new tag to the Exif data:

Software: GraphicsMagick 1.3.19 2013-12-31 Q8 http://www.GraphicsMagick.org/

Please add an option to disable this.

[Bob Friesenhahn]

GraphicsMagick is not competent enough to edit EXIF data yet. It saves the original EXIF data as is (but not yet in TIFF format). It does add software attributes to file formats like TIFF which support such a thing. In fact, the string you provided matches the format of the TIFF Software tag exactly.

Do you not want the software which wrote the file to be revealed?

[Jean-Louis Grall]

Exactly, I am manipulating TIFF files.

I tested with ImageMagick and LibTIFF. They don't add Software tags nor info about the software editor. I found out because I was testing to see which would give the smallest files, and GraphicsMagick was bigger because of this, but I did not find anything about this in the documentation.

And yeah, of course there are also occasional situations where it is useful not to reveal those infos.

There is the -strip option, but it is an all or nothing switch. I don't need to edit the Exif with GraphicsMagick: as you said it's not his job. I wanted to keep the metadata as they were before the execution of GraphicsMagick, but it is not possible yet.

[Bob Friesenhahn]

The value of the software tag is that if there is any problem with the way the file was written, the software to blame for the problem can be identified. The information may also help the reader read the file correctly if it is somehow dependent on the software which wrote it. If anything, the current software tag is incomplete since more useful information could be added.

GraphicsMagick is adding some other tags automatically (and unconditionally). ImageMagick also adds some other tags automatically (and unconditionally).

Regardless, I am looking into ways to have more control over these tags.

[Jean-Louis Grall]

Thanks.

By the way, I just tested, but I didn't see ImageMagick adding any tag. I looked at the file with LibTIFF's tiffinfo.

[Bob Friesenhahn]

I see ImageMagick adding three tags for the file I am testing with here. It may depend on the file and the version of ImageMagick.

[Bob Friesenhahn]

Normally we hope that users are proud of the free software they are using. Regardless, I just committed a change which allows syntax like:

-set software ''

to block GraphicsMagick from adding a software tag to TIFF files. Note that the software argument is an empty string. If the string is not empty, then it will be used as the value of the tag. Otherwise the behavior is identical to now.