First of all, my english is bad, so I'm not even sure, if it's called "merging" or you would name it other way.
I'd like to get this basic effect:
(click for larger view)
The effect, when the picture is so smoothly changing into the blue color.
I guess, that this is probably made of two layers, one with the picture and the second one with blue-and-white background, plus used some Multiply on it, but the main point is still, how to change (now the white color) smoothly into the blue one.
Edit: Huh, now I reminded of some Gradient tool I tried a few times to use and that solves the previous problem pretty much. But it can be used just to merge two colors. I would rather find some technique or tool, which could be used to merge two pictures - I mean, when I have for example two pictures lying nearby without any change, then I'd like to make the edge, which they touch each other by, smooth.
This is one I made some years ago:
(click for larger view)
I stressed the edge line between the two pictures here in preview.
I was doing this picture just for fun (I hope you see, that in the lower part there is a sea, but in the upper part there is a river ). I tried several color and brightness enhancements to make them similar, but the edge between those two pictures is still easily recognizable..
I hope you roughly understand, what I'm looking for.
Thank you for any advice.