[Therion] Resizing or scaling a replacement background image

[Henry Bennett]

What about using imagemagick to resize the new image?

  magick new_sketch.jpg -resize 2550x3300! fixed_sketch.png

Henry

On Fri, 3 Apr 2026 at 18:53, Bill Gee <bgee at campercaver.net> wrote:

> Hello everyone -
>
> I am not sure how this should be handled, or if it even CAN be handled ...
>
> A few weeks ago we went to a section of a cave where the original sketch
> has some problems.  Rather than resketch the entire section, we took the
> original sketch and made corrections directly on it.
>
> Now I want to update the Therion map.  Six months ago I used the
> original sketch as the background of a .th2 file, then drew as much as I
> could figure out.  Since the update is on the same piece of paper, I
> figured I could just replace the original drawing background with a
> scanned image of the updated sketch.  It did not work.
>
> The new scanned background comes in about 1/5 as big as it needs to be.
> The original elements I drew do not match up, so I cannot draw the new
> stuff on it.
>
> I think the reason is that the original background and the new
> background were scanned at different resolutions.  I did not scan them.
> The old background image is 2550x3300 pixels and the new is 908x1200
> pixels.
>
> What do you suggest?  Is there a way to stretch the new background so it
> fits under the existing drawing?
>
> It might be easiest to ask for a rescan.  The new scan might still not
> line up.  Is there a way to shift the background?  I think there is.  I
> have managed to do it a few times by accident.  No idea what keys I hit
> when that happens.  I have to close the .th2 without saving, then open
> and start again.
>
> --
> ===============
> Bill Gee
>
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