hugin-devs team mailing list archive

[Lukas Wirz <2077833@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

For a given image pair graph cut first generates NFT seam lines, and in
the current form picks one seam line (of the possibly >1).  It will then
subdivide it into regions inside and outside overlap areas, and run the
graphcut algorithm on each pair of entry/exit points.

There are two problems with this: a) If there is more than one NFT seam
line, all but one will remain untreated and typically the boundary of an
overlap area is used.  This leads to blending artifacts. b) Seam line
segments are optimized using graphcut that lie outside the overlap area,
which is expensive and doesn't have any benefit.

Attached is a series of patches that fixes both issues + a few smaller
improvements.

As an aside, I'm aware of two further bugs (but these are less frequent
than the addressed ones, according to my set of example problems): a)
Sometimes a graph cut seam is found between two points but *around* the
overlap area instead of *through* the overlap area. b) NFT seam lines
may be circular and don't intersect the image boundary -- these will be
ignored entirely.  Both bugs lead to blending artifacts.

** Affects: enblend
     Importance: Undecided
         Status: New

** Patch added: "graphcut_improvements.tgz"
   https://bugs.launchpad.net/bugs/2077833/+attachment/5809198/+files/graphcut_improvements.tgz

-- 
You received this bug notification because you are a member of Hugin
Developers, which is subscribed to Enblend.
https://bugs.launchpad.net/bugs/2077833

Title:
  graphcut considers only one seamline per image pair

Status in Enblend:
  New

Bug description:
  For a given image pair graph cut first generates NFT seam lines, and
  in the current form picks one seam line (of the possibly >1).  It will
  then subdivide it into regions inside and outside overlap areas, and
  run the graphcut algorithm on each pair of entry/exit points.

  There are two problems with this: a) If there is more than one NFT
  seam line, all but one will remain untreated and typically the
  boundary of an overlap area is used.  This leads to blending
  artifacts. b) Seam line segments are optimized using graphcut that lie
  outside the overlap area, which is expensive and doesn't have any
  benefit.

  Attached is a series of patches that fixes both issues + a few smaller
  improvements.

  As an aside, I'm aware of two further bugs (but these are less
  frequent than the addressed ones, according to my set of example
  problems): a) Sometimes a graph cut seam is found between two points
  but *around* the overlap area instead of *through* the overlap area.
  b) NFT seam lines may be circular and don't intersect the image
  boundary -- these will be ignored entirely.  Both bugs lead to
  blending artifacts.

To manage notifications about this bug go to:
https://bugs.launchpad.net/enblend/+bug/2077833/+subscriptions