[nSLUG] Gimp help? (Re: Image utility for Linux?)

Mike Spencer mspencer at tallships.ca
Tue May 15 23:40:28 ADT 2007

So I need help with Gimp.  Other stitching options weren't adequate
(some details below if anyone is interested) so I'm reduced to doing
it manually, one image at a time, with Gimp.

Here's my problem: 

    + Working with two PGM images, A & B, that have substantial overlap,

    + Open image A in a Gimp window

    + Open image B (same height but narrower, overlaps A) in another
      Gimp window

    + "Select->Select all" in B's window

    + "Edit->Copy" in  B's window

    + "Edit->Paste" in A's window

          All of image B is copied to A's window as a floating layer.

    +  Choose "Move layers..." from the tool menu

    +  Manually align the floating copy of B with the part of A that it
       overlaps in the A window.

    + "Image->Fit canvas to layers" in the A window.

This appears to work perfectly.  Now I need to make these two layers
become all one image and save it.  

But I can't figure out how to do that.

    - The "Display navigation" window shows exactly what I want but the
      main, A window shows a checker board where the overlaid B image
      is larger than the original A image.

    - The "Image->Merge visible layers" and "Image->Flatten image"
      options are grayed out.

    - The "Layer->Anchor layer" option doesn't produce the desired

    - Saving the A image as a PGM brings up an offer to "export" the
      image so as to merge the layers.  The saved result has white
      where it's larger than the original A image.

    - Other twiddles too numerous to list haven't helped.

RT the huge, F html M?  Well, I've read part of it.  I'm still
groveling around in it but haven't found an answer, other than that I
should use the "Image->Flatten..." option which is unavailable --
grayed out.

Surely this is a commonplace move.  Any suggestions?  WHat am I



    pnmstitch, both the version in NetPBM and the one on SourceForge,
    doesn't work.  At least for my images, it only produces a mess.

    My homebrew hack in C works better than pnmstitch but not well
    enough -- accurate to +/- 2 pixels in 1 image out of 20, else 10
    to 20 pixels off.

    Other apps appear to be huge packages designed to deal with the
    arcana of color and contrast balance, lens distortion,
    perspective, parallax, special problems in medical imaging
    etc. etc., all way more complicated than my humble grayscale
    scans.  Since downloads in the 10s of megabyte are difficult for
    me, I've so far avoided them.

Any pointers welcome, tnx,
- Mike

Michael Spencer                  Nova Scotia, Canada       .~. 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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