please improve image compare

Ideas for improvements and requests for new features in XnView MP

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kbyork
Posts: 12
Joined: Sun Mar 30, 2014 7:19 pm

please improve image compare

Post by kbyork » Sun Mar 30, 2014 8:51 pm

There is a lively thread on this at "Show viewing offset in image information" http://newsgroup.xnview.com/viewtopic.php?f=60&t=29528.
Discussing using XOR, a Javascript plugin and switching between overlay-ed images.
[memo: I think all these comments means it is an important issue.]

For me, there would be two primary reasons to compare images:
  • Taking a burst photos from my cellphone (and then picking out the best)
  • or comparing photos from the web
But before you can compare photos, you need to make them align with each other!
I suggest:
  • letting the user add a couple alignment points on each photo,
  • use the alignment points to scale and align (the in-memory copies) of the photos,
  • and then view the images in an overlay-ed manner.

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JohnFredC
XnThusiast
Posts: 2010
Joined: Wed Mar 17, 2004 8:33 pm
Location: Sarasota Florida

Re: please improve image compare

Post by JohnFredC » Mon Mar 31, 2014 12:16 pm

Support++

This is a great idea.
John

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oops66
XnThusiast
Posts: 1999
Joined: Tue Jul 17, 2007 1:17 am
Location: France

Re: please improve image compare

Post by oops66 » Tue Apr 01, 2014 8:04 am

Support+ too
XnViewMP 0.82 Linux X64 - Ubuntu 16.04 LTS - X64

CameronD
Posts: 306
Joined: Wed Aug 01, 2007 1:28 pm
Location: Australia

Re: please improve image compare

Post by CameronD » Sat Apr 05, 2014 8:02 am

kbyork wrote:...But before you can compare photos, you need to make them align with each other!
I suggest:
  • letting the user add a couple alignment points on each photo,
  • use the alignment points to scale and align (the in-memory copies) of the photos,
  • and then view the images in an overlay-ed manner.
You raise some excellent ideas here.

I regularly use the Picasa image viewer to flip between overlaid images, because it retains zoom factors and manual image shift values (not retained permanently).
This is mainly to do things like identify critical focus details to pick out the best image from a group.

The ugly thing about Picasa is that it insists on sliding each new view in from one direction or another, which is extremely frustrating when you are trying to compare images.
The other problem is that the alignment has to be done as trial and error by manually dragging the images and flipping between until they align - there is no way to simply select a point and say "align to this".

I would suggest a single reference point, giving X and Y translate, is enough for many situations.
A second reference point then give you translate, rotate and scale, if they are necessary.

In my photos, the subject is often moving slightly. In these cases the extra precision that might be gained by two-point referencing is not worth the effort, because the subject will invariably have moved in a way that is not correctable.

An overlay with 50% transparency might allow you to select the first reference point in both images at one time.

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