Hi all,
since I am doing photomapping of terrain,
I have experienced, that the light tends to change progressively as I shot photos.
The problem is, the flight is following zig-zag or spiral shape and as a result I have gradual variation
of brightness and contrast across ortophotomap.
In my case I am striving for fast response, not for HDR quality, and it might be difficult to repeat a mission
that takes up to 2h of UAV flight.
The question is, are there any tools that can linearly/gradually or maybe automatically apply some correction to a list of images?
We are talking abotu 300-3000 photos per flight, up to a few times per day. A real mill.
I am aware of ImageMagick toolset, but it is not a solution:
The problem is that any automatic method I know gathers statistics over a single image, then applies the correction to one or many.
Also ImageMagick scripts I tried to apply by merging photos etc show insufficient processing speed of Image Magick (it is general tool, with dozens of intermediary memory copies/logic layers during processing a script).
What is needed is a tool that analyses 3..tens..all neighboring images (consecutive in the list) and applies slowly changing correction.
I know that somebody will advise fixing exposition in the camera but thsi is NOT the way to go in 50% cloud cover changing the lighting 8 times during the flight.

What is needed is something like Deflicker algorithm used in movies, but this would be ideal but I doubt it exist for photos.
At the moment I am looking for anything that works.

I know the issue could be known to ppl doing Timelapses but I have no idea what are the solutions (I guess they usually merge the results into a movie, then apply Deflicker filter in movie processing soft, but the resolution, compression and quality is lost).

At the moment typical application of autobalance or histogram equalize/anything leads to photos where 1 out of 20 pops up with very off colors or other parameters.
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  • T3

    I would echo Kris Nackaerts advice to look into Hugin. It has a capability that sounds like what you looking for. At it's core is a set of very powerful open source image processing tools called Panotools. Unfortunatly it is command line driven and difficult to use so several people have created GUI front ends to make it easier to use of which Hugin is one. Even with a GUI panotools can sometimes be difficult to use especially with the specific requirements you have, but maybe bGatti could look at a custom front end if he doesn't already have the right tools in his bag of tricks.


  • The perfect solution as far as I see could be an image collection tool, something like Adobe Bridge or Lightroom where user can select image series and apply a color correction on those images. Then a user can varies a value of correction trough that list with simple curve. Who is familiar with video editing or video special effects probably knows what I mean. Just replace video frames with images. Is there something like that?
  • Well considering that I also have a problem to adjust an image set that has 12000 images (yes 12k!). The problem is color correction between flightlines. I'm using a professional photogrammetry software with unique color correction method. In overlapping areas software automatically put so called color points. The difference between image's IHS values are calculated and then applied in triangulated manner. That means each color point present a corner in color correction triangulated network. Correction values for each pixel of ortophoto is then interpolated from this "color correction triangular network". It is a neat and interesting approach that usually contributed to some perfect results but unfortunately not in my case. To many images. So I would also like to try manual image based approach where some kind of interpolated corrections are possible.
  • T3

    Yess will upload 1% of the problem. But not as attachment ;-)

    Give me some time, must select an area that is not restricted to publication.

  • 3D Robotics
    Can you add an example picture to the post, showing the problem?
  • T3
    bGatti: OK PM sent.


    BTW the closest match for the job is either:

    MSU Deflicker plugin from VirtualDub, or better: GBDeflicker which is Adobe After Effects plugin.

    Both are for movie processing only, and making 10MPIX resolution movie out of jpegs is not that simple nor practical. We are talking about 3000 photos here, 3000 originals, 3000 RAWS as input movie, 3000 RAWS as output movie, 3000 output pics.

  • @kristof,
    I write a software that does color adjustments for pros, I'd like to address this issue, can you supply small image sample? Will it include gps log?
  • Enblend seems interesting for you: http://enblend.sourceforge.net/details.htm

    Gain some experience how it's used in Hugin ( examples on enblend results at http://hugin.sourceforge.net/tech/ ). Detailed info on how Hugin uses enblend: http://hugin.sourceforge.net/tutorials/Blend-masks/en.shtml


    How Enblend 2.x Works
  • T3

    RAW is out of question because of quantity of data and required shotrate below 4s. Unless I missed a camera that can do 1000 RAWs every 4s.


    The flight altitude is 200m agl on average.

    300m on rare cases.

    Almost never below.

    Over 300m no chance.

  • Hi,
    Enblend looks interesting, but like a black box from the first look. I will try that...

    Regarding a program capable of handling several hundred images, try ImageJ (http://rsbweb.nih.gov/ij/).
    The task sounds like writing a small plugin for that. There are many good examples.
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