Re: [Savannah-hackers] savannah.gnu.org: submission of cardpics

[address@hidden]

> address@hidden writes:
>  > Hi,
>  >
>  > If GNU GPL applies to images, we use it. Yes!
>  >
>  > For the copyright notice, jpg images accept
comments, but
>  > it seems that png images do not.
>  >
>  > So we'll use that way to put the copyright notice
for jpg
>  > images, but we need another idea for png images.
>  >
>  > The tests with comments were made with gimp-1.2.1
(not
>  > the latest one)
>  >
>  > Thanks for helping on this subject that is new for
us!
>  > Yves
>  >
>
>       One idea I had was to insert the copyright notice
using
> steganography. Writing a few lines in the README file
explaining
> how to re-apply it on a modified image is needed since
it's
> hardly common knowledge. Some steganography methods are
modification
> resistant but this is not 100% safe. Explaining how to
re-insert
> it is certainly simpler. The README file should also
contain an
> example line to display the copyright notice.

Pngcrush should be OK. But I wonder if it uses
specifications of PNG or if it is stenography.
According to the PNG specs, it is possible to add text
inside the png file besides the image.

pngcrush: http://pmt.sourceforge.net/pngcrush/
png specs: ftp://ftp.uu.net/graphics/png/documents/
text inside the image: see
ftp://ftp.uu.net/graphics/png/documents/png-1.2-
pdg.tar.gz, then PNG-Rationale.html, section 12.10
about "text strings". An URL for easier consultation
exists but I don't remember where it is.

Yves

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