On Wed, 30 Jun 1999 04:23:05 +0200, Ralf Muschall
<rmu### [at] t-onlinede> wrote:

>Glen Berry wrote:
>
>> POV-Ray automatically insert a small text file into each of out images
>> stating the author's name, copyright notice, etc. This text file would
>
>Something like this might help e.g. in the IRTC, but doing it
>automatically might be a problem: It could violate the privacy
>of the user if he forgets to avoid/delete the comments e.g.
>from an indecent or illegal image. Bad things like this
>have already happened with user IDs included in MS Word files.
>

Please remember that my suggestion was for a user-created text file. I
believe the MS Word ID numbers were something the program itself
inserted into the file without the user's permission or control. My
idea wouldn't be any invasion of privacy at all. If you are purposely
placing private information into a voluntary, user-defined image
header, you are your own security risk.   :)

My intention was largely to maintain the identity of the author and to
assert a copyright statement. True, most people would never see it
because few programs will let you read it, but it could conceivably
help cut down on unauthorized image appropriation and copyright
infringement, especially on the internet. It would give you at least
some evidence that a stolen image file was yours.

If someone wants to create an "anonymous" image file, simply don't
enable the feature in the povray.ini file. It also wouldn't be enabled
by default, because a pointer must be established to the
user-generated text file. Only the user would be able to provide that.

>> assign a DPI value to the image. Currently, I have to do this in a
>
>IMHO the DPI value is not a property of the image, but
>of the printing process, hardware, requested paper size
>etc. Passing the information the other way around
>is IMHO more useful (e.g. the printer tells the renderer
>how many pixels the image should have in order to fit
>on a given sheet with minimal dithering trouble).
>

If by "printer" you mean a person working at a service bureau, you
will be sorely disappointed to learn (as I was) that the *vast*
majority of these individuals can't think in terms of pixels. They
only think in terms of DPI. The number of pixels in an image is nearly
irrelevant to many of them.

True, a basic image file doesn't have to have a DPI value assigned to
it, but all the printers (humans, not hardware) that I have talked to
assume that a DPI value has been attached to an image file. They are
so blind to the concept that an image file has no physical size, it is
almost maddening. Professional graphics programs will alter the DPI
value for an image when adjusting the size for printing and they will
store this value in the image file for future reference. At that
point, even an image file without a DPI field will then have one
added. I would just like to take a short cut and have POV insert this
information at the time of file creation. It shouldn't be hard to add
this. Trust me, when working with a commercial printing service, it
would cut down on the likelihood of errors in the printing order.

>
>Modern bitmap formats (at least PNG) support comments,
>but reading them requires a nontrivial activity by the
>user. I think is would be better to stay portable
>and have the creator supply a text file containing the
>informations. This is easier to create (at least for
>people with DOSen, where PNG is not so widespread yet)
>and to read (e.g. in HTML pages).
>
>Ralf

First, the suggestions weren't meant to provide information that was
easily human-readable and obvious to anyone who viewed the image file.
In the case of copyright assertion, it is actually an asset that the
information is obscured. If it were obvious or supplied as a text file
it would be more likely to be fraudulently altered. 

Second, portability is not affected one bit by using these standard,
documented features of the image formats. If you were actually
referring to accessibility instead of portability, please see the
above comment.

Many graphics programs insert information in the images they produce.
Things like headers for copyright, the name of the software used for
creating the image, and other details are implemented in many other
programs. I'd just like for POV to also have these same little
"finishing touches" the other programs have.

Later,
Glen Berry

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