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.
Comments
I have a no-go on motorway data. However, there is
http://www.aerialrobotics.eu/pub/winter-high-overlap/
Shot in very high wind. There are no strong temporal flicker,
but in turn there is constant fade from red to blue which is so fast (this was still 2.5h to sunset)
that it affects the map quality. for neighboring strips.
The plane was flying only 40km/h since it was the lightest protoype.
Full flight logs in the directory.
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.
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.
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
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.
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.
Hi,
Enblend/enfuse is what your looking for : command line for your several thousand of pictures is possible with a bit of code... Already done it, really awesome program !
The photomerge function in Adobe Photoshop CS4/CS5 is good. But I have only used it for a limited number of images. Not sure how well it would hold up when using hundreds of images.
Does your camera support RAW images? That would allow for much more aggressive brightness and color correction without introducing artifacts.
Will not work because digital camcorders use interframe compression.
Splitted photos will have bad quality (and typically lots of noise as well).
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