PanEdit Lite: Original Panoramic Images

In addition to stitching multple flat images to form a cylindrical panoramic image, PanEdit Lite can also be used to trim and align the ends of a single panoramic image captured using a rotating panoramic camera. Such cameras have been use for over 100 years and they an excellent means of capturing a scene without needing to align a number of flat images.

When a scene is captured with a rotating panoramic camera, the resulting cylindrical image generally covers more than 360 degrees. A photographic print of this image can be scanned to produce a digital image of the scene. PanEdit Lite can be used to trim the resulting image to exactly 360 degrees. The overlapping areas at the ends can be blended to create a seamless panoramic image. In addition, image skewing errors arising from the camera or scanning process can be corrected.

The following notes describe how to load a panramic image and how to modify this image. When finished, use the "Save" button in the main window to save the resulting panoramic image as a file.

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Panorama stitching tool

Loading a panoramic image

To process a panoramic image with Panedit Lite, first open the single panoramic image file representing the scene. This can be selected through the file open dialog, or the single image may be dragged onto the empty main window. Next, click on the Scene button to open the Edit Scene dialog. In the Edit Scene dialog, select the "Wrap Ends" option, then select "OK" or "Apply" to confirm the choice.

Selecting the "Wrap Ends" option when there is only one image indicates that this is a cylindrical panoramic image and not an ordinary flat image. This selection is irreversible (after selecting "OK" or "Apply"). The following image shows an example of a single panoramic image:


In this case, the main window is similar to that seen when importing multiple flat images, except that the Exposure button is disabled. There is no exposure balancing function for cylindrical panoramic images because the entire scene is captured in a single photograph and exposure balancing is not a problem.

The original panoramic image also appears in the Images window located below the main window. In this case, the Images window contains only a single wide image representing the "unrolled" original image with no corrections for the viewer's perspective. The main window shows the same data corrected for the viewer's perspective.

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Adjusting a panoramic image

After loading a panoramic image and selecting the "Wrap Ends" option in the Edit Scene dialog, click on the Stitch button to open the Edit Panorama dialog. The following figure shows an example of this dialog:


Horizontal end alignment

The horizontal alignment of the overlapping ends of the panoramic image can be controlled by the "Left" and "Right" values in the "Clipping" section of the Edit Panorama dialog. Values entered here take effect when the "Apply" button is selected. These values can also be controlled by double clicking on the main window (to open the Image Edit window), then dragging the left and right clipping boundaries with the narrow white double-arrow cursor. These changes take effect when the left mouse button is released.

Selecting the left and right clipping boundaries may be difficult at first because these boundaries will coincide with the edges of the original image. Before trying to select these boundaries, make sure the Image Edit window has been scrolled completely to the left or right limits. Beware of selecting the black double-arrow cursor (for resizing the Image Edit Window) and the wide white double-arrow cursor (for controlling the cropping boundaries).

Vertical end alignment

After clipping the ends to achieve the best possible horizontal alignment, one may find that there is a vertical offset between features on the left side of the end-seam and the corresponding features on the right side of the end-seam. This vertical offset can be controlled by using the "Skew" value in the "Other" section of the Edit Panorama dialog.

The size of the skew value should equal the number of pixels by which features on the left side of the end-seam are offset from the corresponding features on the right side. For example, if the ends are initially offset by 10 pixels, the the skew value should be set to either +10 or -10, depending on the direction of the offset. This value takes effect when the "Apply" button is selected. The vertical alignment

Blending the ends

The ends may be blended by selecting the "Blend" button in the main window.

Portions of the original image can be excluded from the blending operation to prevent ghosting or other prolems. The blending limits are controlled with the "Left" and "Right" values in the "Cropping" section of the Edit Panorama dialog. These values take effect when the "Apply" button is selected.

The left and right cropping boundaries can also be controlled using the wide white double-arrow cursor to drag the edges of the black cropping boundaries. These values take effect when the left mouse button is released.

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Copy and Paste operations

Any standard Windows-based image processing software tools, such as Adobe PhotoShop, can be used to modify the original panoramic image being used as the source of the current panoramic scene.

The following procedure may be used to modify the original panoramic image:

  1. Double-click on the main window to open the Image Edit window with the original panoramic image.
  2. Press "Ctrl-c" to copy the original panoramic image to the Windows clipboard.
  3. Open the preferred image processing software tool,
  4. Use tool-dependent techniques to paste the original panoramic image into the chosen software tool.
  5. Use tool-dependent techniques to modify this copy of the original panoramic image.
  6. Use tool-dependent techniques to select all or part of the modified copy of the original panoramic image, and to copy the selected area to the Windows clipboard.
  7. With the Image Edit window still open, press "Ctrl-v" to paste the modified image into the Image Edit window.
  8. If the pasted area does not cover the entire original image, use the hand cursor to drag the pasted area to the desired destination within the Image Edit window.
  9. Right-click the mouse (or left-click outside the selected area) to confirm the destination of the pasted image.
The "Ctrl-c" and "Ctrl-v" functions are the standard Windows methods for "copy to clipboard" and "paste from clipboard".

Panoramic images modified by the cut and paste operations cannot be saved by PanEdit Lite. If one needs to preserve a copy of one of the modified panoramic image, one should use the file save or image export functions provided by the image processing tool used to make the modifications.

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Last modified January 13, 2000.