Posted by
Kenneth Sloan-2 on
URL: http://imagej.273.s1.nabble.com/registering-a-stack-advice-needed-tp5020546p5020554.html
Interesting idea.
I think I would be satisfied if SIFT enforced the "maximum pixel movement"
restriction. Perhaps I don't understand the semantics of this parameter?
It's not clear to me where this restriction is actually applied at the moment.
Certainly, *some* pixels move by a LOT when the image is rotated by 90deg!
The central idea is to strictly limit the amount of movement produced by
the transformation.
In my case, I think I could benefit from very elastic matching. The images
vary due to translation, rotation, and some perspective changes. But, the
changes are very small. Large enough to require registration, but strictly limited.
I suppose the constraints are similar to matching overlapping areas of adjacent tiles
in a tiled image where the individual tiles are already in a good approximation to
their correct locations wrt each other. I want a "tweak" - not an arbitrary
transformation.
The killer is that I see a real need for some rotation - but I need to limit it to (say)
20deg. Limiting the transformation to "translation-only" prevents disaster, but
it also precludes useful improvement.
So...this seems to boil down to 2 questions:
a) can I convince SIFT to do this (short of limiting it to translation only), or
b) is there another method implemented for ImageJ that handles this situation
better than SIFT
I'd *really* like this to be automatic, so methods that involve manually locating
landmarks are out. If it comes to that, I already have my own code for that
type of registration.
Last question: is the fact that SIFT allows a 750x750 image to rotate by 90deg when
"max pixel movement" is set to 25 EXPECTED BEHAVIOR? or, is this a bug?
--
Kenneth Sloan
[hidden email]
Vision is the art of seeing what is invisible to others.
> On 23 Apr 2018, at 03:43 , Gabriel Landini <
[hidden email]> wrote:
>
> This is more of a related question/request than a solution to the original
> topic.
> Sometimes there appear to be "distracting" landmarks in some slices that might
> not contribute to a proper alignment.
>
> I wonder if there a way of restricting the SIFT search so it only considers
> points inside a ROI (or a set of those) to then apply the transformation to
> the whole slices?
> I guess that a not-too-elegant way of doing this might be to clear outside all
> ROIS, perform the SIFT alignment then apply the transformation to the original
> stack, but would that work (maybe the artificial edges that are generated by
> the clearing outside the ROIs act as new features?), and how to do this?
>
> Regards
> Gabriel
>
> --
> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html--
ImageJ mailing list:
http://imagej.nih.gov/ij/list.html