Enblend versus PTStitcher masks -- quality of region selection


This web page supports PanoTools posting http://groups.yahoo.com/group/PanoTools/message/9497 .

The point of this page is to show that the masks generated by PTStitcher often have strange shapes, far from optimal.

Here is my original scene as shown by PTGui.  It is a 2 x 4 array of images, shot handheld with a small auto-everything film camera.  I have not cropped the film scan edges here, so you can see some of the frame boundaries.


Now for demonstration I replace the original images with color- and texture-coded images, to make it easier to see the visible regions computed by PTStitcher and Enblend.

First, the images in the same order as in the original scene.


Here with the order reversed.  You can see that the layout is almost symmetric, top-to-bottom, and that the images are spread out fairly evenly side-to-side.


Now for the punchline.  I render with PTStitcher and Enblend, and mark the edges of visible regions with white lines so that you can see them better.

Here are the visible regions computed by PTStitcher.  They have strange shapes and are very far from optimal.  Many of the seams are near the edge of a source image instead of being in the middle of the overlap between two images.  There are strange 45-degree bevels near the image edges.  I do not know how these shapes are computed, but they are typical in my experience.


The ones computed by Enblend are much better.  The seams are much closer to the center of overlap regions.



Even the Enblend regions do not seem quite optimal in the sense of using pixels as far away from an edge as possible.  The boundary is too low (not centered top-to-bottom) and seems more jagged than it ought to be.

Here are region boundaries drawn by hand using a farthest-from-edge criterion, on top of a picture with transparent layers.


If you want to play with this, here is a .zip file containing the PTGui project and test images: PTStitcherRegionsDemo.ZIP


For more information, reply to the PanoTools posting or contact me at .

Rik Littlefield


PS.  Here is the final image after contrast blending and various other touchups.  6100 x 4880 pixels.  Looks very nice printed at 305 dpi.