Editing Seams with PTStitcherNG

Prof. Dr. H. Dersch - HFU Furtwangen

Create Seam Mask

PTStitcherNG can create and import a version of the panoramic image which contains information about the seam positions. This image is equal in size to the default panoramic image, but each source image is replaced by a monochromatic image with unique color. This color is interpreted as index for the corresponding image.

To create this mask we call PTStitcherNG using the option -a

PTStitcherNG -a -o mask.tif project.pts
In this command project.pts is the PTGui project file (traditional PtStitcher scripts work equally well). Notice the extension .tif for the output name. That way we overwrite the format setting in the project file, and force TIFF-output. A lossless format must be used to preserve the exact index colors. This is the output image for the current example:

This image may be used for diagnostic purposes, or for planning different stitching schemes. In the following we use this format for editing seam. Using the -e option of PTStitcherNG we can later use this image as input mask for setting seam positions. By altering this image we can therefor control placement of seams.

In the simplest scheme we just paint into this mask image. However, we have more control by overlaying this mask and the panoramic image inside a graphics program (Gimp, Photoshop) as described in the next chapter. PTStitcherNG offers a second output mode which creates a nonblended version of the panorama, which is particularly suited for this purpose:

PTStitcherNG -b 2 -o no_blend project.pts
The special panoramic image is named no_blend in this example. The option -b 2 disables the multiresolution blender, and just merges overlapping image areas with equal weight. That way it is possible to see mismatches between source images, and decide where to place the seam.

Now we have created all prerequisites to start editing in our favorite graphics program.

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Copyright H. Dersch 2010