Hi Bill,
I have put the two data files on the directory bayer.
Bayer.zip with the ecliptical images and Durer.zip with the Durer
maps.
The way is to find some pixels position on the image and connect to
them the ecliptical/equatorial coordinate.
For an image are normally necessary 4/6 points.

Ciao Dario

--- In guide-user@yahoogroups.com, Bill J Gray <pluto@p...> wrote:
>
> Hi Dario,
>
> I'm not sure I follow you here... I would indeed be interested
to
> see the .TXT database you've built, but am not clear on what it
> contains? RA/dec values for individual pixels? Or... ?
>
> Some time ago, I found a site with some images from
historical atlases:
>
> http://www.lhl.lib.mo.us/events_exhib/exhibit/ex_atlas.shtml
>
> and attempted to add these images to Guide charts. I
encountered
> two problems: aligning the images was more difficult than I
expected,
> and there is some significant distortion when adding images with
so
> large a field of view. (The system Guide uses for displaying DSS
and
> RealSky images is a simple one: for each image, the RA/dec
coordinates
> of the four corners is given. Guide finds out the on-screen pixel
> coordinates corresponding to each of those four corners, and
stretches
> the image to fit that quadrilateral. This works wonderfully for
images
> up to, say, ten degrees or so. Beyond that point, the image
isn't
> really "flat" enough for this simple method to work.)
>
> -- Bill
>