@Berit: That might be the way to go, I will try it. Just time is a factor sometimes and our mosaics usually consist of 3000+ images (largest one was 45,000), and since Photomerge/Photoshop can only render up to 150 or so (varies with resolution), the final mosaic consists of many many of those patches I showed here. But if this needs to be done step by step, I will do.

To your second point: In this example the images were not optimized before their use. This was kind of an exception. Normally, I run them all thru a batch job, with Match Color against a reference picture, which takes care of "harmonizing" levels and colors throughout the set, some Replace Color to get rid of the red & magenta, the dark corners turn into after level correction, and some extra lighting on the edges as well. The Lens Correction filter has some potential here (Vignette Removal). Thanks to our 50% overlap, the corners do not get visible much, but there's always some to see, of course. Are you doing underwater mosaics as well?

Thanks for your thoughts, g

@Berit: No, don't know the National Gallery stuff (how they do it), but it might be worth to figure out. Also what I see as an option: Maybe there are other programs around, that could import layered psd files but do a better seemless rendering. I tried Gimp, but it can't do it. Unfortunately, there's not much competition for Photoshop. And the really big boys, that do stitching of arial or satellite images (Google Earth), they might use some specialized software that would not be available to us... Cheers, g

Hi PE, I tried that, correcting one patch manually (which worked), but Match Color does not fix the others nicely. So maybe the manual way, patch by patch, is the way to go for now.

Or just investing more time in preparing the individual stlls before using them, however, I find it very hard to get rid of any gradient caused by uneven lighting or the tinting effect. It works to some extend by applying tone correction via adjustment layers thru a gradient mask, but I do not get our stills perfectly even from corner to corner, but to be honest, the rendering engine of Photoshop should be able to deal with it. Incase you have ideas of how I could try to harmonize the initial stills, go ahead. My knowledge of PS is not too bad, but I'm not really familiar with pixel theory (histograms, curves and such). There might be some potential there. I might post an example image later, for people to play with. I do not have any high end experience, as with fine tuning pictures for print or such. Just hands on

As it seems, this weird gradient has been accepted as a bug by Adobe, so hopefully they will fix it in a future release.

Thanks for your thougths,

g

I use Match Color a lot during prep of the individual stills. However, it has limits to what extend it can remove color and brightness gradients in the images (caused by uneven lighting, as said)...

Thanks. This indeed looks very tekkie, I will need some time for this. Coding is not what I would call my mother tongue....

g

H there,

@TLL: you're right with what you said about the subjective element. Getting spoiled is easy, but staying ambitious is good as well. I do these mosaics since 2003, when Photomerge was part of Elements only. Then, in the first years with CS and CS2, I never had this bug with the color gradient being applied to the final merge. This started with, I guess, CS3 and I think it's due to enhancements Adobe made to the programm (making it more "intelligent"). Unfortunately, sometimes enhancements have dark sides and cause unexpected issues elsewhere. And since we are a minority (making large merges), these do not get fixed, since the majority, stitching what, 20 image panoramas of their home and garden do not suffer. Their images have strong contours and contrasts and the issue gets effective only on uniform images like underwater sediment or, in your case, landscapes shot from above. Going back to CS or CS2 is no option, since only the newer versions give me the processing power I need, also is the blending much smoother.

I played around with gradient masks but I haven't got the right touch yet. Even if I get rid of the color differences, there will always be a brightness gradient, since borders of the images are always darker. And then, the weird gradient is a bright / dark one, not a red / yellow one. Not much better. Also, each batch job has to work for thousands of images, so has to be a compromise. I just cannot spend more than a day for a 1000 image mosaic, or a week for 6000 images, time is money on a ship (and elsewhere).

I just think the solution would be, splitting the "Seemless tones and colors" function up into "Seemless Blending" (doing soft blending but not changing the colors) and "Seemless Color Transitions" (just dealing with the colors). And making both optional by check boxes...

So far,

g

Courtejoie, I owe you big time, that was the best tipp ever, it's exactly what I needed. Or the pictures. Many, many thanks, the results are almost seemless now, no weird color gradient or anything, I'm happy! Post could be closed, however, it was a pleasure, thanks to everyone contributing!!

g