Align images

Ideas for improvements and requests for new features in XnView MP

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nji9
Posts: 114
Joined: Wed May 13, 2020 10:33 am

Align images

Post by nji9 »

This suggestion as a preliminary step for comparing two images
viewtopic.php?f=60&t=44090

As to do the latter the images have to be aligned
(corresponding pixels for the same subject position).

Typical usecase:
You have two images showing the same thing, but as the images are
from different sources they may be against each other
- shifted horiz./ vert.
- rotated
- zoomed (resized) (in both direction same or different amount)

Params for that operations would be
- interpolation method (bilinear, Lanczos etc.)
- shifting precision (subpixel?)

Doing this manually is an unpleasent, labourisly task,
which can be done by algs quickly and precisely.

When the adjustment values have been determined
you have to decide how much adjustments each of the images
should be done to match the other one.
(For example: 30.4 degrees rotation. Say rotate 50% image A and
50% of image B).

This would be a fine quality operation, moreover simple to use.

Maybe it should be included in the "Image compare"
as a optional preliminary step?

Sources of algs:
Used in movie deshaking (for example https://github.com/gu-t/Deshaker)
or photo stacking (for example align_image_stack in https://en.wikipedia.org/wiki/Hugin_(software)).
(3D depiction (for example https://stereo.jpn.org/eng/stphmkr/)
also aligns two images, but in a special way that the pictures
are not aligned exactly.)

EDIT: Typo in last link.
EDIT: Params for operation: shifting precision (subpixel?)