Adjust for Panorama

What it is

Adjust for Panorama is a GIMP plug in which distorts images so that they could be smoothly joined together for a panoramatic view. When taking a series of snaps from one point around yourself, it could be nice to join them and make a panorama view. The problem is that the images usually don't match at the boundaries. This is because you have most likely a camera with flat chip, so the resulting photos are like postcards arranged to a polygon. What we would really need is the postcards to be bended on a cylinder.

Adjust for Panorama takes the photos and transforms them so that they are like bended on the cylinder. After this transformation, it is usually very easy to join the pictures into one, big, panoramatic image.

How to install

On Linux systems, it is quite easy, just get the source code from svn, copy them locally and issue
sudo make install

Of course, you need GCC, make, gtk+ developer libraries and gimp developer libraries.

After that, the new command should appear in the Filters > Distort > Adjust for Panorama...

Hopefully someone will contribute with compiled binaries for Windows systems.

How to create panorama

Adjust for Panorama does not do anything else than distort the images, so to create a panorama photo, the standard manual steps should be used as described on many places. So just in short:

  1. Load all images using File > Open as Layers...
  2. Use Adjust for Panorama command to distort the images
  3. Move the images so that their overlap properly. Use the layer transparency to see the good fit
  4. If you didn't use tripod, you may need to manually rotate some of them
  5. Use Color Curves to adjust the colors of particular layers
  6. Use Layer Masks to make the transition from one image to another smooth
  7. Merge all visible layers
  8. Use rectangle select tool to select the nice part of the final image, copy the selection and paste it as a new image

How to use Adjust for Panorama

After selecting a layer and clicking Adjust for Panorama... command, a dialog box appear with three double values to be set. Actually only the first one - View angle - is used for the calculation. This value gives the horizontal view angle (in the x direction) of the picture. The result very depends on how you manage to estimate this value.

If you are not sure about how big the view angle should be, there are two other helper values which might simplify the task - Focal length and Chip width. The focal lengths is usually embedded in the original jpeg image, so right click on the image file and selecting Properties and Image should give you an answer to this point. The chip width should be given by the manufacturer in the camera manual. Changing one of the letter values will automatically recalculate the View angle value.

Sometimes, especially for compact cameras, the focal length value may be given as recalculated to the 35 mm film. In any case, it is always necessary to test the correct view angle on two files. When the View angle is OK, the two images should show perfect match both in x and y directions.

There is another value called "Inclination". This gives angle in degrees of the camera above the horizontal plane. If the series of snaps has not been taken in one horizontal plane, then this value causes that the images are recalculated to a cone instead of the cylinder. Finally a perspective correction is applied so that the images can be horizontally aligned.

Finally, if the "Perspective correction only" check box is checked, the plug-in can be used to linearly correct the perspective.

Last edit: Pavel Krejcir 2012-11-28