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Frequently Asked Questions

Last update: 1 February 2010

I want to edit my image after blending. Can Enblend create a layered output instead of a flat image, so I can adjust the seams?

No. A drawback of multiband blending is that there is no good path for manually editing the result. Enblend does not just find a single optimized blend mask like the kind you are used to working with in Photoshop, where each output pixel is a function of the input pixels directly underneath it. Enblend looks at an entire region around a pixel in all of the contributing input images and does an average. For typical digital camera panos, these regions can be hundreds of pixels in diameter. Furthermore, the size of these regions varies dynamically based on how "edgy" the pixels are. Edges are blended across a much smaller distance that open areas like the sky.

I double-clicked on enblend.exe, and a window flashed briefly but nothing happened.

Enblend is a command-line utility. You have to run it from a DOS window and type parameters on the command line. See Manual for more information on the available parameters.

Enblend.exe only crashes on my Windows machine, even when I do simple things such as asking for its version number.

The default binaries of Enblend are compiled with SSE2 support. If your CPU does not, there is a special version of the binaries that might work.

Enblend says that images are redundant. What does this mean?

It means that the image(s) that are being added in the current blending iteration are completely overlapped by the previous blended images. These images don't add anything new to the panorama, so there is no way to draw a transition zone between old pixels and new pixels. Also, Enblend cannot decide for you that the new pixels are somehow "better" than the old ones. It just keeps the old pixels and ignores the new ones.

Why do my input images need alpha masks?

Enblend is designed to work with images with unusually shaped borders, like those that have been warped by PanoTools. The alpha channel is required to indicate which pixels in the file are part of the image versus the pixels that are around the border of the image.

When the alpha channel is white (255), it means that pixel should be part of the final panorama. When the alpha channel is black (0), Enblend won't use this pixel for blending. Don't use feathering in the alpha channel. You can specify to use a pixel or not, but it does not mean anything to say "use this pixel only N percent". That kind of constraint does not work with the multiresolution spline technique.

You can use the alpha channel to remove unwanted pixels before running Enblend. A common example is to erase pedestrians that are moving between shots. If you erase the pedestrian in the alpha channel, Enblend will consider this a "hole" in the panorama and will fill in those pixels from a different image.

What about multilayer TIFFs, like the ones that Nona produces?

We need to extend the image import/export capabilities of VIGRA to understand files that have multiple images in them. For now, you can run tiffsplit on the multilayer tiff and run Enblend on the resulting tiffs. You still get the disk space savings in that each layer excludes the large transparent borders. Tiffsplit comes with the libtiff-progs package.

Why does the order of the images on the command line matter?

Enblend works best when the overlap between images is large. Therefore, you want to order the images such that the next image overlaps the previous images as much as possible.

Alternatively, try using the -a flag. This tells Enblend to try to assemble as many non-overlapping images as possible before blending. Sometimes this does a good job at maximizing the amount of overlap, but it depends on your photos.