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DPChallenge Forums >> Hardware and Software >> Averaging out the colour in a sky using CS3
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07/02/2008 11:59:21 AM · #1
I have a panorama that has been stitched together, where the land joins you cannot notice but where the sky joins you can notice, I can select the sky easy enough but other then cloning, burning and dodging is there an easy way to just get the colour to average out somehow? I've tried some Gaussian blur but that only helped a little!

Here is a small version of the photo so you can see what I am talking about!


Thanks
Robert
07/02/2008 01:20:54 PM · #2
To directly answer your question, other than selecting the sky and filling it with a solid or gradient fill, I think it would be hard to do; you might select the various areas and use Levels or Curves locally, but I don't think that would help that much.

Autostitch software has a setting where it tries to balance out the colors between the various shots, but it doesn't always work.

One thing which seems to be important is to shoot all of the source photos with the same exposure settings, which should make the colors match up as you pan the camera.

Here is one of mine which exhibits the same problem as your photo; there are a couple of others in the same gallery which do not.

07/02/2008 01:24:53 PM · #3
maybe try a color match on the individual files before stitching them together?? Not sure if this would work, but it might be an easy thing to try. use the first file as the source file, and then use the other three individually as the destination. Accessible in Photoshop CS3 under Image...Adjustments...Color Match (I think anyway. I don't have the application here to make sure)
07/02/2008 01:44:24 PM · #4
i know that problem, can really be a pain in the ass.
i think the problem is not the color, but the vignetting from wide angle photos. they become darker at the edges, so you'll get a darker-brighter-darker "wave" throughout your sky when stitching. so maybe running ALL the photos through a devignetting software (photoshop has it built-in or if you're shootin raw it's even better) before stitching them might solve the problem.

if you're using the cs3 built-in pano stitcher (which imo is the best of all i've tried) you can adjust levels and colors on every single shot of your panorama even after stitiching because photoshop leaves the single shots in layers. then adjusting the levels from the left to the right (or the other way around) to level the color and brightness works also quite well.

hope that helped :)
07/02/2008 02:32:17 PM · #5
Originally posted by Mephisto:

i know that problem, can really be a pain in the ass.
i think the problem is not the color, but the vignetting from wide angle photos.


Good point! What about shooting wide-angle, with a greater-than-usual overlap, and then cropping out the center, non-vignetted portion and stitching those?
07/02/2008 02:42:29 PM · #6
Try using the vignetting correction tool in Lightroom to lessen the effect in each shot before stitching.

The ultimate solution is shooting at f/11 or f/16 to eliminate vignetting since you will most likely be using a tripod for these kind of shots anyway. I try to overlap at least 1/3 into each frame when doing panos.

Best, Hrannar

Message edited by author 2008-07-02 14:43:14.
07/02/2008 02:56:39 PM · #7
The problem is very common with panos shot with a WA lens, yup. When making panos there's no real reason to use a lens wider than whatever will give you adequate top-to-bottom coverage; side-to-side is better served with more images, not wider images, and not just for reasons of vignetting. This also minimizes any minor distortional jumps from frame to frame. As a rule, I'd be shooting pano with camera in portrait orientation for that reason.

R.
07/02/2008 03:21:53 PM · #8
Originally posted by Bear_Music:

The problem is very common with panos shot with a WA lens, yup. When making panos there's no real reason to use a lens wider than whatever will give you adequate top-to-bottom coverage ...

One nice feature of Autostitch is that it can handle stacked photos as well as side-to-side neighbors -- see the example of mountains on their home page. You can make two or three horizontal passes to get a greater vertical dimension than possible even by shooting in portrait orientation.
07/02/2008 03:31:07 PM · #9
Originally posted by GeneralE:

Originally posted by Bear_Music:

The problem is very common with panos shot with a WA lens, yup. When making panos there's no real reason to use a lens wider than whatever will give you adequate top-to-bottom coverage ...

One nice feature of Autostitch is that it can handle stacked photos as well as side-to-side neighbors -- see the example of mountains on their home page. You can make two or three horizontal passes to get a greater vertical dimension than possible even by shooting in portrait orientation.


Yeah, I'm aware of that. I'd worry about it on serious landscape work though because of such issues as the misregistration of moving cloud shadows between vertical passes... I'd prefer to work with single vertical frames. But I haven't done panos for quite a while, so...

R.
07/02/2008 05:06:28 PM · #10
Originally posted by Bear_Music:

...I'd worry about it on serious landscape work though because of such issues as the misregistration of moving cloud shadows between vertical passes...

You could "pan vertically" -- take two or three shots panning up or down so that all those elements are aligned left/right, then swing the camera to the side and repeat.

Or shoot on cloudless or completely overcast days ...
07/03/2008 04:33:30 PM · #11
thanks for your replies.

The shot was taken not long after I had my 350d and I had not much idea about anything other than the P setting! The shot was hand held and I did use Autostitch to merge them as I found CS2 and the canon software nowhere near as good.

I'm getting there with the sky, lots pf patience required!!
07/03/2008 05:10:33 PM · #12
Autostitch has a setting to help equalize areas such as this -- I can't remember what it's called right now gain compensarion, but it is described in the Help file. You might try restitching with various settings to see if you can get a better match. I often process two or three times at a very small size (10%) -- usually takes less than five minutes on my slow computer -- before I try stitching at a printable scale.

My Canon S3 has a mode called Stitch-Assist just for doing panos; it locks in exposure settings with the first frame, and gives you a small image of the just-shot frame alongside the live preview to help with alignment ... this may not work with an SLR viewfinder system though. I try to use that mode whenever I'm shooting panos -- it especially helps for ad hoc situations where I don't have a tripod, or time to use one.

Message edited by author 2008-07-03 17:46:29.
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