Scan/image stitcher

[CharlieC]

One of the problems with scans is how to stitch partial scans of big pages together. Suposedly this can be done with GIMP or Photoshop but this usually turns into a frustrating exercise since the graphics packages can't rotate the images in fractions of a degree. A software solution that seems to work pretty well is "Hugin". Runs on most operating systems and is is Open Source (free).

hugin - Panorama photo stitcher

There's a tutorial on stitching scans at:

Hugin tutorial — Stitching flat scanned images

Regards,

Charlie

[simiankind91]

Hey, thanks for the tip, I'll have to check out Hugin. Right now I use Microsoft Image Composite Editor (Google Microsoft ICE and it'll come right up) to stitch JPEGs together. It works like a charm. Rotates, stretches, does it all without any complaints. It does get a little fussy at times, but I highly recommend it for stitching photographs. Don't know how it would work on scans of line drawings though.

[RyanShort]

Trick is to learn how to use the grid and rotation tools and snaps in a program like Gimp. Basically if your scans are flat and the same resolution you do something like this:

1. Take both images, cut and paste them into separate layers in a base image with a large canvas.
2. Move one image into place where you want it. Take the image you want to stitch and adjust the layer's opacity, so you can see the layer beneath it.
3. Align known point on lower right edge of Left side scan with other layer's same point on lower left edge of Right side scan (confused yet? )
4. Set up grid so grid point is directly over aforementioned point.
5. Select desired layer to rotate and turn on the rotate tool and with snap to grid on, move rotation center-point to aforementioned point.
6. Turn off snap to grid and pick other known point towards top of page and drag it to the point on opposite image.

That should work.

Ryan

[Art Deco]

Originally Posted by CharlieC

Suposedly this can be done with GIMP or Photoshop but this usually turns into a frustrating exercise since the graphics packages can't rotate the images in fractions of a degree.

Looks like you've got a some good alternate solutions, but in case it's helpful to anyone, I use Photoshop CS2 v9, and it can indeed rotate images in fractions (hundredths) of degrees.

To do this, use "Edit > Transform > Rotate". Then you can either grab a "handle" and manually rotate, or for more fine adjustments, enter a numerical value in the Angle box. I tried 0.05 degrees, worked fine.

Happy stitching!

[CharlieC]

It's the small non-linearities of scans which seem to cause the most problems. Hugin seems to work by applying non-linear transforms to the scans to merge them together - you have to supply control points for it to do this. There are software tools to find the control points but these are covered by a patent so are not in the Hugin package.

Regards,

Charlie